Ten Tec Delta Recap: Part 2


So, I’ve recapped ten boards in the Delta, and have attained a nice clean internal signal condition that looks good on a scope, and to the ear, when loading a hundred watts into a dummy load.  Also, most of the weird birdies and random noises are gone, and the rumble of the “display hiss” that was previously heard in the background, (but very noticeable), is also gone. So, I think the recapping was a success. I have a few miscellaneous caps to replace, but the priority is off for those. Of the thirty or so caps that I replaced, most were not leaky. A few were leaky, and replacing them may have been all that I needed to do. But, in-circuit tests of old electrolytics are not very effective in many cases.

All of the replaced capacitors (all thirty-something of them) – had higher ESR values than the new ones, typically double. I’m not sure that is really an issue.  For one thing – new caps do have lower ESR from the factory than the ones that -when they were new – were put into the Delta forty two years ago.

One astonishing thing is that all of the caps (except the leaky ones) – had very large increases in capacitance. Typically, a 4.7 uF cap in the 42 year old radio would now read 6.5uF or even 7 uF. Many times electrolytics are used in a fashion that allows for pretty strong changes in value, while still retaining functionality. In a few cases, this is not so. In any case, I solved that problem by replacing them. So, it wasn’t all that bad. Being retired, I have some time, and I probably devoted about a day and a half (if one doesn’t include a lot of puttering around), to the recapping project. I’d say to those thinking about doing it: go ahead. You’ll likely add some benefit to any radio that’s say – forty or fifty years old.

There remains some strong image appearances (always in the same place(s)), that I’ll need to take care of, but that’s going to be another level of investigation. I think there were some images in the Delta that couldn’t entirely be eliminated.  We’ll see. 

73’s – Ron / WB8LZR

Ten Tec Delta Recap: Part 1

Figure 1: With capacitors in hand, recapping begins.

The recapping of the Delta 580 is a project that I’ll document, even though I’m not sure others will find the information interesting or useful. As time goes on, there are fewer and fewer of us old analog radio aficionados. Let’s face it, old analog radios had an Achilles heel. Unlike digital radios, in analog radios the analog signal path is subject to signal purity degradation all along its path. Digital radios mostly have that problem only at the front and back ends. So, with an analog radio comes a bunch of signal conditioning devices in the form of electrolytic capacitors. The Delta has thirty nine of them.

Figure 2: Board 1: 4 caps, 3 bad. one good.

As I mentioned in the introduction of the 580 blog post, the old Delta was sounding pretty raspy. I took a look at the signal path, and decided to recap the TX path first. I think most would agree that is the most important signal purity issue. So, glancing at the block diagram, I decided to pull the SSB gen board first (shown in Fig 2). I hope it is not a harbinger for the rest of the boards, because of the four electrolytics on it: one was thoroughly trashed, two had objectionably high ESR, and the last capacitor tested good. I’d kind of like to see the ratio working the other way around (hihi).

Figure 3: TX carrier signal much improved after replacement of bad cap on board 1.

The biggest capacitor on the SSB gen board (a 33 uF job) had a 50% change in capacitance value, a double ESR, and a little leakage. Perhaps that is why the signal was 100% improved on the scope shot taken after the board was reinstalled back into the Delta 580. I can’t stop now though LOL. I already bought the caps, and I’m in the mood to do it. I have to say that Ten Tec’s modular board arrangement makes this easier than it’d be on a monolithic board rig. I could be done now, and I’ve not have taken the entire circuit out of the case. It takes a couple minutes to pull a board in the TT rigs, and a extra minute to put it back in (“in” is harder than out because you have to keep the spacers from falling off hihi). I probably have ten minutes in the SSB board’s recap desoldering and resoldering procedure.

So, the straight scope display does not show any appreciable hum modulation. But, the scope input taking the AM detector output from my test jig does indicate a touch remains. So, we sill continue plunking away …

Figure 3: The IF Amp board is the next board on the signal path

So, I moved on to the IF Amp board. It’s the next board on the path that contains electrolytics. If one looks at the picture in figure 3, one gets a bit of the impression that says he’s looking at a DIY board. I kind’a like that about Ten Tec’s earlier stuff. It’s about what I might do if I were doing an HB job on the board. Definitely not mass produced. I have a vision in my head of the little ole lady stuffing the board at a table in Sevierville, TN in 1981.

Will give the results of board #2 on the next post. 73s. – Ron / WB8LZR

Ten Tec Delta 580


The Ten-Tec Delta has been on the bucket list for rounding out my Ten-Tec analog radio collection for quite a while. It’s a little bit hard to find these days, but I finally managed to snag the radio from a seller who could not give me a full picture of its condition. Thus, I was a little concerned that perhaps the radio might require a *lot* of work to do a restoration. Let’s face it. Forty and fifty year old radios almost always need at least a little TLC if they haven’t had much of it lately.

Fortunately, my checkout of the radio yielded some good results, as I found the transmitter PA to be doing the full 100 watts, the receiver to be working on all bands for which it had crystals, and the Cosmetics to be probably a little above par. I used it over the Easter weekend,  for listening to signals on the 30m band.


Figure 2: The two empty crystal slots need to be filled to round out the upgrade for 17 meters &12 meters

As I wrote, cosmetically the Delta that came into my possession was pretty clean, but electrically it was a little unclean on both transmit and receive modes. It’s the sort of thing that happens to forty two year old radios, especially if they’ve not been stored in the best of environments for long periods of time. In my opinion, it’ll require a recapping to clean it up. Recap projects can be really involved, and they can be pretty simple. It’s a matter of the circuits, how complicated they are, and thus how many electrolytic capacitors are involved.  Fortunately for me, the Delta is one of Ten Tec’s more simple rigs, and has a very manageable number of electrolytics in it.

I decided that, since I was going to make a project of it, I’d upgrade the radio to enable 17 and 12 meter band operation. It came with the crystal for 30 meters, but not the crystals for 17m or for 12m. For the Delta, the only part that need be added is the crystal itself. I have located some crystals on Mouser, but haven’t yet determined if they will adequately mimic the originals that Ten Tec supplied.

The crystal frequency that is required to enable 17 meter operation on the Delta is the frequency of the bottom of the band added to 11.5 Mhz, so it is: 18.0 + 11.5 = 29.5 Mhz. The frequency of the crystal needed to enable 12 meters on the Delta is 24.5 + 11.5 = 36.0 Mhz.  Edit: Yeah, I know for legal reasons that 18.068 MHz is the bottom of the 17m band, but from Ten Tec’s circuit point of view, it is 18.0 – hihi.


Figure 3: The bottom view of the Delta shows the crystal box.

The number of electrolytic caps in the Delta is 39. This is much more manageable, relatively speaking, than the situation for the Corsair II, which has 97 electrolytic caps. The Triton IV has only 24. So, one can see from the cap count how the circuit grew from the Triton thru to the Corsair (97).

The top view of the radio is shown in the photo (above).

Update on the Longwire


Figure 1: Nicely wound transformers (not my doing tho LOL)

So, I’ve been using the 75.5 foot (23m) longwire for a couple weeks (the length of the wire was picked by the analysis conducted by VK6YSF on his site, with the goal being to find a wire that was not too long (<100 ft) and could be an easy POTA Qrp antenna).  On forty meters and lower, I guess it’d qualify as a shortwire antenna hihi.


After some fussing I settled on a 60 foot counterpoise to go along with the antenna. Then I added a triple rod earth ground on top of that (driven down at the antenna feed point). The photo shows the 1:1 current balun that I added to the 9:1 unun already in the box).  IMO the 1:1 current balun was needed to reduce mantle radiation and RF coming back into the shack.  According to my understanding, current baluns can perform dual service as ununs). Before adding the 1:1 balun, I had mantle radiation and some noise in the receivers. Afterwards, both seem to be gone.

Even with my dipole and its choke balun, I usually have at least a couple hundred milli-watts of reflected power. With the balun/unun combination on the longwire, the tuner is able to make the SWR absolutely flat: zilch, nada reflected power, and no receiver noise. It works a treat IMO. However; the radiation pattern is pretty high when the wire end is low to the ground. VK6YSF has the antenna a few meters off the ground, because he was trying to emulate POTA conditions where one might not have a high anchor point for the end of the wire. Raising the end of the wire (to maybe 30 degrees) – lowers the radiation angle, and gives better results.

Note that, due to the high voltage nodes, I’d never run the wire with more than QRP levels of power. So, a lot of hams are using EFHW antennas, which would seem to be limiting in the number of bands that could be used. The only band this antenna will not tune is 17m, and I have a nice loop for that band.

Man, I love the balun winding. I didn’t do it myself. A nice Ebay store owner did it for me, and wow did he ever to a good job of it. Both of the transformers are double core – good for big power on another antenna (but not the end-fed longwire we’re discussing here tho, LOL).

I absolutely love the hybrid (1:1 balun + 4:1 unun) from BalunDesigns that I put on the 17m loop. It works a treat. I wish I could post photos of the windings, but the thing is too high to reach at the moment hihi. With the hybrid setup, I seem to be able to tune a number of bands (other than the 17m target band) to a flat SWR on the loop. The performance is pretty miserable on other bands though, and I suspect that all my power is heating the cores. They tell you NOT to do this sort of thing on their site LOL.  As usual, none of this is advice, since I could be entirely full of it.  Best 73’s – Ron/WB8LZR

The Triton IV needed a Checkup

Figure 1: The old S meter on the Triton 4 is registering signals above zero again.

The Triton IV is a radio I’ve had close to my inner ham’s happy thoughts for a long while. It’s antiquated by today’s standards, having been manufactured first in 1976. It’s almost 100 percent analog, unless you count a few old gate chips on the control and calibrator boards. Its 70s era-styled case is infamous for being the flimsiest ham radio chassis enclosure ever built. For this reason, it has always been advisable to place it on a stout table, keeping the brass pounding and attendant vibration damped down to a suitably less energetic level. But, the receiver is pretty sharp, has no hiss or phase noise, and the sensitivity has always managed to be plenty enough for my rag chewing QSOs.

It’s that sensitivity that plummeted one day, while I was working twenty meters. Suddenly, I could hear the other station barely. More alarmingly, the noise had also disappeared. It was as if the antenna disconnected, and I was picking up the little bit of signal that could penetrate the circuits directly through the case. To check this, I sent out a signal and watched the SWR, letting the other ham know I was going to have to QRT.  The transmitter was OK, and the SWR was perfect.  That mean’t that … Oh Oh.

Note: Quite a while ago, I had anticipated an eventual “Oh No!” moment. Accordingly, I located a half dozen or so NOS 40823 MOSFETs for the junk drawer.  So, the dread that might normally accompany the last paragraph was diminished somewhat. HiHi.

It immediately dawned on me that the RF amp’s MOSFET input (front end) transistor had given up the ghost. So, I took the Triton apart to do a replacement, feeling that was something I most certainly would have to do. Checking the voltage on the calibrator wire coming out of the preselector partition seemed to show that gate #2 on the MOSFET was operating correctly. The drain, source and first gate terminals of the MOSFET still needed to be checked. This was no easy chore.

I am one to compliment Ten Tec on almost every aspect of their builds, but the preselector stack on the Triton is definitely a PITA. The resonator knob is attached to an elevating core assembly that moves the ferrite cores of L1 and L2 up and down on the RF amp board. This is a bit nifty, as an idea. It works well. But, the RF board is nested below the elevator assembly, and is screwed into the chassis from the other side of the board. So, you have to pull the board out from the bottom AFAIK. I suppose you might work a screwdriver in between the partition walls somehow, to loosen the screws, and then take it out from above. Before any of that can happen, you have to desolder about a dozen wires and component leads. This was a long, messy job just to get a couple measurements on the MOSFET.

Run across a dental pic or a dental mirror at a flea market? Buy it!

So, I put my tiny dental mirror to work, hoping that with the mirror, I could successfully land a probe onto the PC board foil for the other gate, the drain, and source, without blowing anything up.  BTW, if you ever run across a dental mirror at a flea market or antique store, definitely buy it! It was worth the $5 already, and I got a nice pic along with it.

Well, getting the flashlight to line up with the mirror while working the probes was seriously challenging for an old guy with only two hands.  I don’t think I landed the probe properly, but in the process of pushing and pulling things, I miraculously solved the problem.  Suddenly, the S meter popped up to 20 db over nine.  W1AW/4 was calling “CQ contest”.  What a beautiful signal that was to hear!  Of course, this meant that I had a cold solder joint.  After forty seven years of life it for some reason decided to lift its head.  It just goes to show ya! Sometimes it’s easier than it looks.

In retrospect, it might be that the resonator knob and attendant elevator assembly put a little mechanical push or pull on the RF board as it “elevated” or “de-elevated” – and this eventually pushed the cold solder joint open.  Or not.  So, I made sure that the cores were centered in the shafts, so that further mechanical stress could not happen, and heated some of the terminals.  Don’t know if I heated the right one(s), but at least I know where to look if the problem ever returns.


A Shortwire on 80 meters.


Figure 1: The trifilar wound “unun” in a weatherproof minibox.

I had an assortment of antennas, but on 160 and 80 meters I had nothing of consequence.  I have an 80m horizontal loop, but stopped using it due to its proximity to my building structure and attendant problems. I had been looking at VK6YSF’s longwire web page, and the little 23 meter (75.5 foot) end-fed “long wire” antenna that he had formulated was quite interesting to me. He had taken the time to do a complete analysis of the impedance of a variety of not-quite random wires, assessing the impedance on each ham band. He settled on 23 meters as a good fit for almost all the bands (except 17 meters). I already have a nice loop for 17m, so didn’t feel hobbled by the antenna’s high impedance on that band.

He uses a 9:1 unun to feed the end-fed longwire (it’s really only a longwire at 20m and above). Probably one should slap a 1:1 current balun in behind the unun to keep coaxial radiation at bay, in my non-expert opinion.  Balun Designs sells a nice hybrid unit that is both a 4:1 unun and a 1:1 current balun in one box.  I ordered one for a 4:1 loop connection, but I don’t think they have a 9:1 combo version, which would simplify my longwire antenna arrangement.   I procured a nice 9:1 unun with a 2 inch core (1.5 KW capable) – and tried a few of the bands.  I never bother with the little cores because the big ones will work with QRP as well as QRO. For end fed wires, it’s always only a QRP (max of a couple watts) power level that I use.  I could easily load power from the Omni A into the antenna using, in addition to the outside transformer, a tuner in the shack. The impedance transforming unun is outside in a minibox, and a run of RG213 coax feeds the tuner inside the shack. 

Some hams think that they can slap a 9:1 voltage balun onto the wire, and all will be good.  But, such a device does nothing to isolate the antenna to prevent mantle radiation or the feeding of RF into your shack.  A good quality 1:1 current balun seems to be in order for that task.  I am a big fan of using transformer baluns instead of chokes.  Some baluns are built with short coax sections that are covered with concentric ferrite beads, but IMO these may not isolate the antenna in all cases.  The “Balun Designs” page gives info on transformer balun versus choke considerations (balundesigns.com: “Striking a Balance.pdf”).  You can search for the pdf on their site.  It seems to me that they are expert in this arena.  They successfully pushed me in the direction of their own product, LOL.

Note I’m not giving advice for how to build your antenna here, but am just writing about what I did with mine.  Incorrect (or for that matter even correct) usage of end fed wires, baluns, ununs, and counterpoises can create high voltage nodes on your wires.  BEWARE of end fed wires and other such things, and don’t say I told you to do it any particular way!  I’m not a qualified balun/unun/counterpoise design expert. For my own preferences, I would never run much power to an end-fed radiator such as what is described here.   QRP power levels of one or two or five watts are in the domain of what I run.  

There! Disclaimer entered.

I found the performance on 40, 30, 20, and 15 meters to be mediocre, which probably is the expectation beforehand.  On twenty meters it may be a bit better than my dipole or my vertical in its favored direction.  The graphs on the VK6YSF page show wildly varying radiation patterns, depending on the band in use. On 17m, my tuner could not do the job.  I didn’t try 10 or 12 meters. Just for grins I decided to load the antenna on 80 meters.  On the low end of the 80m band, the wire is about a quarter wavelength.  On the other end of the band it is approximately a 1/3 wavelength radiator.  I had not harbored great expectations for the use of it on 80m, but after a few days I’ve decided it ain’t all that bad! 

Granted, I currently have nothing else on the band, so cannot make any valid comparisons, but in the first few days many CQs seemed to garner a 579 or 589 or 599 report, so long as the station was within maybe five or six hundred miles.  Conditions may have been above normal, but maybe it is (at least for now) my 80 meter antenna, and I’ll let the vertical and the loops handle the other bands.  When it’s all ya got, of course it’s viable, if it works at all,  depending upon your patience level. It seems to do pretty well on the 20m band.  On that band, it’s a true longwire (equal to or greater than one wavelength). Due to the up and down complications of band conditions, this is all very much a horse shoes swag of course.

The VK6YSF page is at https://vk6ysf.com/longwire_antenna.htm

Figure 9 on his page is the important one – and shows the tune-able impedance on 80 meters and the other bands.  This antenna should eventually be upgraded to something more traditional, like a high dipole on 80m, but for now it’s easy to run out a length of 75 feet of wire, to get a signal of sorts onto that band. Due to my lot, the full length 80m antenna will be much more labor intensive.

I went so far as to try this wire on 160 meters, and made a QSO there with difficulty, three states away (Hi there W8BJO!).  On 160m it is only a 1/8 wave horizontal wire, so expectations are considerably lowered.  The efficiency may be a bit better due to the counterpoise I use in preference over an earth ground. I DO have an earth ground on the coax feed for the equipment!   

Addendum 02/25/23:

I played around with the counterpoise length quite a bit.  Its length seems to make a substantial difference, depending upon on the frequency of operation.  Looking at the info at aa5tb.com/efha.html – you can get an idea about counterpoise lengths.  For a half wave antenna, end fed, he shows that the impedance starts to climb quickly as the counterpoise reaches about 80 percent of the antenna length, ultimately going to about 5,000 ohms.  


Figure 3 on the aa5tb page shows the impedance chart vs counterpoise length.  I still haven’t settled on a good length for the counterpoise, because it is a multiband antenna and the counterpoise is subject to a percentage of the vagaries associated with the antenna wire itself.  So, I’ll continue to experiment, and maybe eventually I’ll settle on the perfect counterpoise length for a 23m longwire LOL.

Again, none of this is design advice or a recommendation!  73, – Ron

Fixing a Corsair’s Digital Readout


The Corsair II developed two problems simultaneously. First, the radio went “dead” in terms of RX and TX, except for a little noise. Secondly, the digital readout blanked (to 9.0000 Mhz), and stayed there. I’ve worked on Tritons and Omnis, but up to this point I’ve had limited experience with the Corsair II. Deciphering the fix that was needed in order to get the Corsair II back on the air put me on more intimate terms with this fine little radio from the year 1983.

If the display had been stuck, but the radio had been otherwise OK, I may have taken longer to get to the answer. As it was, I immediately targeted the PTO/Osc/Mixer lineup for a first stab. The aim was good, as it turned out to be the Osc/Mixer board (80975) that was at fault. For those who’ve owned Ten Tecs, the workings of them are pretty well trodden information. But for the passerby who might think that an old-but-not-yet-antique piece of gear might be an attractive addition to the radio desk, I’ll explain the backstory. While some digital radios are intricately wound into the display and control mechanisms, and need them in order to work at all, the Ten Tecs (at least the early ones) were still all-analog radios, with the digital part added as a more convenient feature for frequency readout. This is the case with the Corsair series, which work perfectly fine without the digital display, as the radio also sports an analog tuning knob with ticks for frequency on the front panel, just like the earlier radios like the Omni A,B, and C, as well as the Triton and Argosy, etc.  “Perfectly fine” may not be perfect for everyone, because one would need to count the number of complete knob rotations to know which part of the band he was in (hi hi).

The display can stop operating due to the display drivers and such, but after my investigation and eventual fix of my own Corsair II,  I’m convinced that some of the display problems seen in Corsairs are really in the Osc/Mixer lineup, and not in the display itself.  There is a RG174 coaxial run into the counter box, which is center/front/top of the Corsair enclosure.  It enters the left hand side of the counter box.  The other end of the coax connects directly to the J-36 connector on the Osc/Mixer board 80975, traversing a thru-hole in the divider that separates the top and bottom circuits in the enclosure, since the Osc/Mixer board is in the bottom half of the Corsair. 

What I’ve always loved about Ten Tec is the way that every major block-diagram part has its own board.  So, working on a Ten Tec is just working on a block diagram in silicon.  Right off the bat, the signal coming into the display/counter box was seen to be too low to switch the input gates (about 93 mV).  The J36 connector on the 80975 Osc/Mixer board also showed me about 93 or 100 mV peak-to-peak on the scope.  The frequency was correct (5.xx MHz when using twenty meters), but the amplitude was too low.

Switching the band-switch allowed the correct frequency to appear on J36 and also on J61 (J61 feeds the actual radio mixer stage, instead of the display box) – for each band, but in all cases there was not nearly enough amplitude.  To me, this screamed “Mixer/HFO board output transistor failure.”  Indeed, a quick look at the bias voltages indicated that the last two transistors on the board were in the tank, and internally damaged.  So, I ordered a new MPS3693 and a 2N3866, and waited a few days for the parts to arrive.

The output of the Osc/mixer board really is two separate outputs. The MPS-3693 feeds the counter box thru J36, while the 2N3866 feeds the whole rest of the radio thru J61. Both outputs were low. When I went to unsolder the transistors for replacement, both of them pulled off easily without heat applied.  They had gotten very hot indeed!  They had MELTED their own solder leads! By my reckoning, they broke down, and subsequent to that generated even more heat, until the pads separated from the leads!

There was another problem.  The Osc/Mixer board cannot be removed without removing the entire band-switch assembly.  Oh nightmare of nightmares!  I have worked on Ten Tecs for a while, and usually don’t run into this kind of design-time miscalculation by them.  There was no way to get to the back of the board in order to resolder the new components, except by total dissassembly.  So, I decided to top-tack the replacements onto the board, point-to-point style.  Ugly, but a whole lot less work. Below is shown the empty space after removal, an then the ugly point-to-point result:

Figure: Empty space on board, where defective transistors were removed

Figure: The transistors were “top-tacked” onto the leads of connected associated parts (i.e., resistors etc)

So, the rig is back in operation, and I have a little more appreciation for what holds it together. I have a few comments about all of this. I love Ten Tec gear, and it is the darling of DIY fixers, no doubt. It’s cleanly built stuff, block-diagram board-built, and usually seems to have great design decisions. But, the replaced 2N3866 transistor still runs quite warm. I haven’t done the calculation to show it, but I think it may have been picked too close to its dissipation limit. The device is spec’d at 350 mW, and I’m guessing it’s grabbing every bit of that. The dissipation is coming from somewhere, albeit I can’t see under the board, where there might be lurking a cause of which I’m currently unaware.  – Just a note for the next folks to build a Ten Tec Corsair (wouldn’t that be nice?!)

It’s likely the 2N3866 failure cascaded to the MPS-3693 failure, as that happens.  So, both the radio and the display got zeroed. The fix works, but is ugly. So, I’m thinking I could cut a little daughter board to hold the fixed transistors, and make it a proper plug-in fix rather than a hack.  It would be easier to mount heat-sinks for the devices if they were properly affixed to a daughter board.  Waddya think? Here’s the MPS-3693 part, and the 2N3866 is only a little more, but I haven’t drawn that in my Gimp sketch, and am too lazy to switch to the electronic-CAD:

Figure: The daughterboard for a cleaner fix would be simple

The MPS-3693 that drives the counter box also seems to run very warm, but it’s not as seriously hot as the 2N3866. I could see the possibility of a failure of either or both devices over a long period of time.  A failure of the MPS3693 would cause the display to continuously readout the IF “9.0000”, or “91.000” – yet allow the radio to continue to work in analog-only mode. This may point to easy fixes for display-stuck Corsairs in certain cases, since many Corsairs on the used market are sold that way. If I were an adventurous DIYer, I might give some of them a shot. There’d be no guarantees, of course, since the display components themselves CAN go bad.  A bad display section might show nothing on the readout display.  So, this rambling adventure is not meant to be advice for anyone else, as I could be entirely full of it, hi hi. 73’s.

Figure: The Corsair before the fix, showing a “stuck” display

Loopy for Loops


Figure:  Plenty of room for upward mobility of the loop

A while ago I planted a trap vertical in amoungst my little back yard “forest” of trees. It works, with patience, to grab a little DX, and the occasional local contact as well. But the noise level observed, when using the vertical, is pretty terrible. Typically it runs around S6 -S7 on the Omni’s S meter, meaning that a potential QSO requires a signal that’s much stronger than say – S1. I don’t have a tower, and am not sure if I want to tempt the locals into action by erecting one. Reconsidering my situation, I realized an obvious fact about my landscape.  Indeed, I have around twenty towers on my lot in the 70 – 90 ft range. Why am I not using them? I grabbed one of the ARRL antenna manuals and looked for a candidate scheme to lace up my trees. After all, it IS the christmas season.

I settled on a loop, and cut it for twenty meters. Yes – it’s much more efficient to cut a loop for 80 or 40 meters since it can be utilized on all harmonics. But, I happened to have a nice spool of 100′ of #10 gauge steel primary wire in my junk box. I cut a section of RG6U as per the formula (L = 246 * V/ f (MHz) per the ARRL Antenna handbook) for making a coaxial transformer via a RG6U/RG213U combination for impedance matching to the high impedance loop – and then ran off a 72′ length of the steel wire for the loop itself. “V” is the velocity factor of the cable.  About an hour and a half later, two of my trees were being utilized as proper “towers”.

I had used loops in the past, and they always had been favored antennas, but had not used a vertical loop in the recent past. I do have an 80 meter loop, but it’s a horizontal affair.  Quickly, I re-remembered just how nice and quiet loops can be. The vertical’s S7 noise level was now transformed to an S1 noise level. Suddenly, I was working all kinds of QRP QSOs. It’s much more pleasant to work an S3 signal on an S1 noise background than it is to work an S6 signal on an S6 noise background.  It’s like they say: the antenna counts as much as or more than the power (that I could reasonable run at this QTH). So, try a loop if you (like me) have forgotten how soothing they are to the ears.

The #10 gauge steel is not something I’d ordinarily use, due to the skin effect / impedance issues that are inherent in it.  But, for higher impedance antennas like loops, the steel works just fine.  It’s strong enough for the hurricanes that like to rip through this area occasionally.  My loop is only ten feet higher than ground level on the bottom, about twelve feet higher than that on the sides, and about 24 feet wide.  So, it’s a bit of a squashed loop.  Loops have ground losses when so close to the ground, the same as verticals.  In the picture, one can see that I have a lot of room for upward mobility in the trees.  So, that’ll be done eventually, when I order a new launcher (for the life of me, I can’t find the old one).  The loop as it is was  done with a 24 ft ladder, which is NOT the recommended way to climb a tree!

So, transmitted signals are still a bit muted for me, pending the lifting of the loop.  But, the reception is fine, and so very quiet.  A recommended aerial by my account.  Try one.  Maybe even for POTA and such, a loop might be useful.  

A Trap Vertical in the Forest


How often have you tried your luck with a trap vertical antenna?  They are often praised for their ability to work the bands in spite of restricted spaces and HOAs.  But, have you ever tried to use one that’s planted firmly in a forest of dense foliage … amid the tall pines and oaks?

Lately, I decided on a whim to try the forest vertical, ignoring for the most part the admonitions that came back to me when I’d floated the idea.  I used a 4BTV with a couple dozen radials, ground mounted in a wooded lot of about a third of an acre, which contained at one point 126 trees.  I’ve since removed a number of them, but many still remain.  I found a space where the minimum disctance in all directions was about a quarter wavelength on 20 meters.  Could the signal make the trip through  the greenery to the outside world?

The first weekend I snagged about a dozen countries from the North Carolina QTH, including Chile, Argentina, Finland, Sweden, the Cayman Islands, and French Guyiana.  These are easy picks for most any Yagi, or even a dipole in good conditions, but the conditions were really pretty terrible.  The MUF hovered just about even with the top end of twenty meters.  Maximum usable frequency is not necessarily easily used frequency HiHi.

Figure: The radial base of stainless steel is a must IMO

Try not to look at the twist-off tie-ins put onto the base right before the rain!  Other than that, I thought the base both looks good and works better than the suggested tie-offs to the ubolts and nuts to secure the radials.  The plate adds only 20 bux – and makes the radials a breeze.

All in all, I’d say that it’s possible to work the bands with a vertical in the woods, if one allows oneself a little leeway on expectations.  My signal reports are a little lower than with the dipoles, but due to the radiation angle the contacts are more DX-ish.  So, it’s a trade off that I’ll make, while I’ll keep the horizontal dipoles and loops for the less DX-ish stuff.

I put down 24 radials to start, and will likely add a few more as time permits./

Figure: Six pound sledge does do a number on the iron pipe support

Analog Radios more Resistant to Electrical Storms?

Over the years I’ve had a number of radios, both digital and analog. In that time I’ve had a number of damaged radios that were impacted due to (I assume) electrical storms in the vicinity of the QTH of the damaged gear.  I have always used lightening arresters and so forth, and proper grounding, but there is a certain amount of energy that gets into the shack from nearby storms that are not producing any direct hits, but still do manage to produce a lot of ambient energy.

I’ve noticed that the old analog radios seem to stand up to the storm, so to speak, better than the digital ones (now this is anecdotal information that only involves four radios, so it could be insufficient for the making of any conclusions).

In the first case I had two radios hooked up to the antenna and rig switching network, with one being an analog (oldie from the seventies) radio, and one being a newer digital radio.  The digital radio suffered a failure, while the analog radio (the oldie) did not.  The second case was similar, with another older analog radio hooked up at the same time as a second digital radio.  The result was also similar, as the analog radio sailed right through and the digital one suffered a failure.

If you think about it, the old analog transistors would seem to be hardier things than a fet or a logic chip.  The MOS technology builds a capacitor into every device, which may not handle a lot of voltage. Often, they do not.  Sure, some of the big MOSFET power transistors can take higher voltages, but many of the others are very low voltage devices.  Any old NPN analog transistor will likely have a collector-base breakdown of over a hundred volts, and often have a collector-emitter breakdown limit of near that amount.  So, they just seem to be the hardier devices.

I suppose that one could go back to the old tube type radios for even more hardening, but that’s too rustic for me.  I’ll stick with the old analog dogs, that are old but not antique!  I guess I just have a hankering for the old things, and this is just another rationalization for me to collect more of them.

Fixing a Power Supply: With a Tube of Caulk?

Figure 1: The “caulk tube fix” can be seen behind the transformer.

My Trusty Ten Tec 260 power supply is a nice hefty one: – it’s capable of delivering 28 amps, and that’s enough to power any of my radios with ease.  Unfortunately, the supply developed the “old power supply” malady of producing slightly less-well-filtered DC current.  The first thought for me was that it was the electrolytic capacitors.  I checked the caps with my brand new ESR meter and a capacitor checker.  Oddly, the caps all seemed to check out OK.

Still, it seemed to me that the main filter capacitor was the culprit, because …

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Fixing Stuff: A TenTec 645 CW Keyer

Figure 1: The ball bearing assembly, extracted from the old keyer

The old TenTec Ultramatic Keyer is still used today by many amateurs, including myself. Its Ultramatic keyer mode was born in 1953, and later overtaken by the Iambic A and B modes. I still use the two of these keyers that I own, but one recently needed a repair … In the video shown in figure 2, you can watch a 35 second walk-thru of the disassembly and repair.

Read more about fixing the old 645 Keyer …

A Corsair II

Figure 3A closer look at the Corsair II (left of photo).  Click to enlarge.

The first thing I did with the new-to-me Corsair II was to check the output voltage coming from the TenTec power supply that accompanied the radio.  These old power supplies can suffer from shifted component values over the decades.  It turned out that the TenTec power supply was putting out around 14.5 volts – a shade on the high side.  I took the cover off, and ran the adjustment trimmer down to a more appropriate 13.8 volts.  The previous owner had mentioned a little problem with the display not always working.  I noticed this too – but the problem seemed to go away when the voltage was reduced.

It took a little while to get used to the Corsair II’s pass-band tuning and its other various selectivity features. Once I got the hang of them, I found that …

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Triton and Me: Back together Again

Figure 1The Ten Tec 540 is playing love songs again

Four times I courted her.  Three times I dropped her.  This time it’s forever.  Over the years, I’d managed to find myself paired with the one whose songs were so delightful, whose voice stuck in my memory for the whole day long.

Impressionable and easily infatuated, my young mind learned of the CW siren, that seductress of the airwaves.  Long into the night, I listened to her soft messages, sometimes drifting off to sleep with my hand on the key, eventually slipping into one of those sweet dreams of hamdom.

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Junk or Joy? Heathkit GR-78 Amateur / Shortwave

Figure 1:  The venerable? Heathkit GR-78 receiver, as it was found in flea market.  

What ham can resist the allure of a piece of vintage gear, sans cover, knob, and a part or three, looking ever like the cartoon character with sprigs of pointy hair wires protruding from it, and connected to nothing?  When we go to ham swap ‘n shops, we brace ourselves ahead of time, lest we not load our trunks with the contents of theirs.  We have time in such cases to revisit the vision of our junk corners at home, and the XYL’s displeasure of same.

But …

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Do you Miss the Olde – QSL routine?

Figure 1: The paper QSL added a touch to the ham’s experience.

Back in the day, the QSL card / post-card was a prized possession.  We lined our walls with them, and anticipated the receipt of every new one that arrived in the mailbox.  These days, it’s an electronic stamp in a database that “verifies” our QSOs, and somehow the romance is lost in that.  Yeah – it saves a stamp, and they don’t have a cheap rate for cards anymore, but it’s hard to wax nostalgic about electrons in a memory chip.  The Olde’ Print shop cards, with the funny home-brew cartoons and personalized touches, really added a dimension to the hobby.

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Unboxing a Forty One year old Ham Radio

Figure 1: Unboxing another Alda 103

Another Alda?  I’ll admit to having an affinity for them.  The one I already have is the 80-40-15 tribander (the 103A) – and the one I’m unboxing is the 80-40-20 tribander (the 103).  The package came in a solid little Home Depot box, and no shaking or rattling could be heard during a shake-test next to my ear.  The question on my mind?  Would I hear more from the speaker of the actual 103 when I finished opening the package and plugging the little gem-from-the-past into my supply?

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Qrp project – filters

Figure 2: The extra harmonic filter is ready for action in this photo.

I’d used a kit for the PA output LPF in the TX box, but when I added an additional filter between the Progrock and the BS170 driver, I just put it on perf board.

I also cobbled together a little coffin for the filter.  using double sided copper clad board pieces, and a lot of solder.  Note the solder does the most good when it’s used on the inside seams, where there is copper-to-copper contact.

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Purple Power

Figure 1: The “separates” approach to QRP (click to enlarge).

On page one of this blog post, I mentioned that 10 or 20 milli-watts probably wasn’t going to cut it, at least not for regular CW (and not the weak signal stuff). So, I procured an amplifier kit from the same folks who provided the “Progrock” kit, and started to assemble it. It’s nice and compact, and (hopefully) will deliver around five watts of power to the antenna when I’m done.

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A New QRP Setup

Figure 1: My recent purchase (from QRP-Labs.com) is shown along with homebrew TTL/RS232. Click to enlarge

I was looking at the kitsandparts “one watter” transceiver, but it’s a “one bander” rig. It looks nice, but I decided that I wanted a little more flexibility in my new QRP rig. So, I went to the QRP-Labs.com site, and found a good way to get the flexibility I wanted. In figure 1 can be seen the Progrock kit. It went together in nothing flat and cost me $18 bux. I’m a happy camper with this setup …

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Looking more Deeply at the Alda 103A

Figure 1: Closer look at the Alda 103A transceiver. Click to enlarge.

The Alda 103 is a favorite of mine (it’s a tranceiver from the seventies, that covers the 80/40/20 or 80/40/15 meter bands on SSB and CW, and is entirely analog). I’ve worked up an “unofficial block diagram” for it – since its creators are, sadly, no longer here to create a colorful, official one.  Forgive the crude Gimp drawing.  I think its etch-a-sketch mode works in a pinch 🙂 .

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Remote CW with Old Analog Rig

opustrxrtplFigure 1: Rough diagram of remote (TX end) for old analog CW rig.

Posted 02/11/2017

I have a couple old analog rigs here in the shack, and I thought it’d be nice to remote them to the easy chair in the living room, or the dining room table, or the back porch deck. Just to complicate things, I decided that I couldn’t revert back to Windows to do this task, and additionally I wanted it to be at least *feasible* to use the remote radio capability from an internet connected place (like a hotel in another state).

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The Alda 103 on CW

Figure 1: CW oscillator level control on the Alda 103 (see text).

I had been operating the Alda 103 CW/SSB triband ham radio, a gem from the seventies, for a couple weeks on the SSB end of forty meters. I received nothing but good reports, such as “very clear and clean” – and “an easy to listen to signal” since I resolved an issue with the microphone input impedance, which on the Alda is slighty different than *any* other amateur transceiver. This was done by putting a Triad audio impedance transformer between the Alda and the Shure 414A Hi-Z microphone…

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The Alda 103A

alda103a-001Figure 1:  An almost forty year old Alda 103A amateur band transceiver. Click to enlarge.

The Alda 103 has a very interesting history. It was manufactured (IIRC) in 1977 and 1978, which means it has a nice complement of the discrete bipolar transistors that are fairly common (now, almost 40 years later) – and thus replaceable. Readers of some of my other articles may have observed that I like to have the ability to fix …

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For the curious, my Alda 103A rig is on youtube:

Youtube Alda transceiver tour

A Cloud Warmer for Eighty Meters

cloudburneraFigure 1:  The cloud warmer for eighty meters.  Click to enlarge.

So, on eighty meters my signals were always in the dust. In the fall season, with thunderstorms hundreds of miles away, I had an S6 static noise level, with crashes above that.  It was enough to drive me back to the forty meter CW band.  The problem was twofold.  First, I had a very “loaded” 80 meter attic dipole, and secondly, it was a dipole.  Hence it was poor to begin with (being both loaded and in the attic), and a great static noise scooper (like all dipoles are).

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Shortwave Weather Faxes with the Ten Tec RX320D


Figure 1: RX320D, by Ten Tec, with “homemade” serial gender changer. Click to enlarge

So, I’d been trying to obtain weather faxes, of the type transmitted by the shortwave weather transmitters run by the US Coast Guard, and do that by using the little Soft66 Lite SDR board.  I’d added a preamp to that line-up in order to improve results, yet it seemed that improvement was needed still. So …

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A Preamp for the SDR

preamp8Figure 1:  A preamp tossed together on a piece of proto-board. Click to enlarge.

The performance of the Soft66 Lite is alright for the price of a couple fast food dinners, so I’ve no complaints.  But, I thought maybe some shoes could help it get a better footing, and bring those sought-after WX faxes down to earth with more clarity.  I thought “Why not give it a shot?”

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Using a Pi SBC with Shortwave Radio


Figure 1: The DIP socket in the little SDR board is populated for a BPF.

New Orleans Coast Guard weather fax operates at 4.317 MHz, so it is far outside of the default (7 MHz) filter bandwidth of the little sidecar SDR. Currently, I have no bandpass switching arrangement in the sidecar, so I have to pull and insert different 16 pin dip sockets loaded with the correct components for the BPF for the frequency I’m using.  Yes – that is a little inconvenient …

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Another Look at the Vanguard 260

vng9Figure 1: Vanguard 260 PL NOAA weather satellite receiver (click to enlarge).

This blog article revisits the Vanguard 260 PL, a weather satellite receiver from the seventies that I found (as a rare bargain) on Ebay.  It covers the 137 MHz NOAA low earth orbit (LEO) APT (image) weather satellite frequencies, when it’s fixed up with the correct crystals.  I love the simplicity of the unit, and it reportedly works well given both the time period of the technology, and the low parts count.

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SoC/SBC Boards for Ham Radio (2)

fldigi-on-pi2withcirrus44Figure 1: FLDigi is shown running on the Pi2, decoding a BPSK signal, using Cirrus audio.

The Cirrus adapter worked just fine on the Pi2, as can be seen in figure 1.0. I took the audio first from the “phones” jack of an old amateur radio receiver, and then from the sound card of a second PC running a browser webSDR page. This audio was connected via the “line-in” connector of the Cirrus adapter in the Pi2 box. In both cases the audio was very good, and was adequate to decode signals while using a only a moderate input level. The noise and spur levels were much less than on an i386 PC based machine I had used for FLDigi/ham activities in the past.

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2.4 GHz Unlicensed Band


Figure 1: Status and printDetail() screen of the pingpair_dyn sample app (click to enlarge).

Finally, the unlicensed band nRF24 devices are talking to each other!  It was a bit of a road trip.  One thing to note is the importance of the status byte, and the other status data.  While a hex 0x0e is normal, a hex 0x00 in the status byte, and/or lots of zeros in the printDetail() output are pretty good indicators that your SPI is not operational, and you’re not talking to the transceiver.  More on this issue follows …

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Ham Radio on a Pi2

quiskplussdrhardwareplusraspberry-1Figure 1: Quisk running on the second “homemade” tablet, which use a Pi2 SoC SBC board. (Click to enlarge).

Some of the other posts on this site refer to my “homemade” tablet, which I subsequently outfitted with components for ham radio usage.  I recently built another “homemade” tablet, this time using a Raspberry Pi2 board for the computing power.

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Note: This author is not affiliated with the Raspberry Pi/Pi2. For information about those projects visit http://www.raspberrypi.org. “Raspberry Pi is a trademark of the Raspberry Pi Foundation.  Figure 1 contains elements of a desktop system and associated programs that have been released under a free software license (Copyright: LXDE team: http://lxde.org). As a derivative work, the respective part of the screenshot in Figure 2 falls under that same license. The full text of the licences may be found at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html.  Fig1 contains another program that has been released under a free software license (Quisk). As a derivative work of that program, the respective part of the screenshot in Figure 1 falls under the same license (GNU GPL). This site/author has no affiliation with the author of the Quisk program. The code and full text license for Quisk may be found at https://pypi.python.org/pypi/quisk/.

SoC/SBC Boards for Ham Radio


Figure 1: Various combinations that have, thus far been considered for ham radio audio duty (see text for explanation).

For the past couple years, I have been attempting to determine what might be the best platform for ham radio and other communications related applications, with a bias projected towards looking at mobile platforms. The graphic (above) shows a few options that I have seriously considered, and a couple for which I have built prototypes to aid in the testing process. The graphic is not intended to imply any capability or lack of capability with respect to the hardware, the SoC chip based SBC boards, or the operating systems. The selection only implies what I have made as a personal preference, for reasons that (shortly) – I’ll enumerate. In other words, the Raspberry Pi may use USB Audio, but I would prefer I2S if I can make it work.  Many alternate combinations are possible, and I have refined a list of preferences for the audio configurations I’ll use.  I have more info about this subject at:

(The link goes to another of my blogs)

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Simple SDR + FLDigi


Figure 1: The graphic shows the layout of SDR, as utilized by hams.  Click to enlarge.

I decided to utilize the simple SDR hardware by using Quisk as the SDR software, and FLDigi as the digital mode software. It was simply a matter of stopping the WSJTx process and starting FLDigi. The FLDigi software picked up the audio feed with no manual intervention. After launch, it presented itself in the Pulseaudio control app (pavucontrol) recording tab, as …

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A Second SDR for the Desktop

Figure 1: I liked the “Soft66 Lite” so much I decided I needed another for the desktop, in addition to the one purchased for the homemade tablet. For the desktop unit, a separate enclosure was needed.

These tiny little things are addicting! The enclosure was outfitted with a couple switches to do bandswitch duty, since (unlike the homemade tablet) there will be no GPIO to apply for that function. A big, clunky SO-238 connector was attached to the box, to accept the PL-259 plug from the antenna coax. And of course, holes were made for the audio and power connectors.

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Using Simple SDR hardware

wsjt-scrn1 Figure 1: The combination of the “Soft66 Lite SDR hardware, the Quisk SDR software, and the WSJTx digital mode software is displayed in the graphic (the WSJTx screen shows two CW signals).

The Soft66 Lite SDR hardware worked well with the Linrad SDR software, for copying CW signals or SSB signals on a variety of ham bands. While that was fun, I decided to take it a bit further, and use the Soft66 SDR hardware, the Quisk SDR software, and the WSJTx digital mode software to copy JT-9 and JT-65 style digital communications.

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A Shortwave Receiver for the “Homemade” Tablet

Figure 1: The “soft66 Lite” SDR (software defined radio) board. It’s a fun thing to build in a spare three hours, and even more fun to operate!

Recently I’d integrated a “homemade”  tablet into the station, for things like receiving weather faxes and BPSK31 transmissions.  I’d been using external receivers to do that, but mentioned that I really wanted to put a “shortwave” receiver board inside the tablet, for an all-in-one effect…

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New (For Me) Omni-A (Analog)


I have always been a Ten Tec fan. As a kid I dreamed about the PM-1, but had to settle for home brew and (eventually) an old (even then) DX-40 transmitter / Lafayette-HA350 RX combo. When I was older, I purchased a Triton 4, and fell in love with the quietness of its noise blanker assisted audio, its filters, and its fabulous QSK. Some time ago, I decided to find another Triton (I’ve had and subsequently sold several, when I wish I’d kept them all!) The prices have crept up, as the numbers dwindle, and Ebay resellers have ascertained that hams will give blood for these units. They are made primarily of discrete transistors, with a smattering of commodity ICs, and so are relatively easy to fix in a pinch.

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Maritime Mobile and the Weather Fax

Figure 1: The pieces and parts for a QDH weather fax antenna

Posted 08/17/2015:

My eventual intent to go maritime mobile is connected with amateur radio in more ways than the obvious. Homebrew construction technique is valuable for other things, and in this case I intend to put it to use while building a satellite weather fax station (maritime mobile version).

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