This weekend I “participated” in the NC QSO party. I’m normally not a contester, but since it’s a local thing for me (being in NC) I decided to work a few QSO party stations. Just to make it a little more interesting, I decided to use a straight key for the event.
I have keyers and use them. But, I like to use a straight key sometimes. My straight key is not your grandfather’s straight key. I toss the 45 year old Bencher paddle over on its side, clamp a big ole iron Bessey wood clamp onto the base, switch the wires around on the bottom of it – and – voila – a straight key is made.
Now, a straight key does not make for a high score. Neither does taking most of the afternoon off to go to a park for a stroll with the XYL in the unusually warm weather. I managed 107 slowish QP contacts, and a few of the rarer counties, but it’s good only to submit as a check log of course. But, I had some fun of the CW kind – the best there is!
Figure 1: Hybrid 4:1 voltage balun / 1:1 current balun used in loop.
I have been playing around with loop antennas for a number of years, and have found that they are gratifying to use for receiving antennas, because they are so quiet. But, it seems that they are often lacking when it comes to using them for transmission purposes.
Recently, I decided to raise one of my loops from its original height of 25 feet, adding an additional 30 feet, putting it just short of the three quarters point on my North Carolina gum tree at 55 feet. When the loop antenna was at 25 feet, it was much flatter of course, and it was cut for twenty meters. I raised it and lengthened it to have a forty meter fundamental. Even with the apex raised, the bottom is still not high (maybe twelve feet on one end), so I did not necessarily expect a big improvement in the transmitted signal. A first week of reports seems to indicate results better than expected.
There was a substantial increase in the RST reports received after raising the loop. For instance, when the loop was in the low position, reports typically were in the range of 54/55/56 with an occasional 57/58/59. Since the loop has been raised, reports are trending towards 56/57/58/59. Another thing I noticed is that received reports are now more likely to be on par with those of the station I’m contacting. So, I guess the old saw is correct, when it advises to put it up as high as you can. A modest improvement in height of only 30 feet has been worth the little bit of time required to perform the task.
Antenna theory tells us to expect trouble with ground losses on certain types of antennas when they are put too close to the ground. I think that partially plays into the observed improvment, but I think there’s a gain increase as well. My antenna is patterned after the W1FB antenna mentioned in QST of October 1984, authored by W1FB and W1SE. Doug (W1FB) wrote that the theoretical launch angle for the antenna is ten degrees, and on harmonics of the fundamental, such as 20 and 15 meters, the gain appears to be 6 db in the favored direction.
The W1FB antenna was listed at 50 feet, so this loop should be on par with his. His antenna fundamental was cut for 80 meters. So, if you have a low loop and are unhappy with the results, see if you can add a modest height increase, and maybe you’ll be as happy with the results as I. Note that the box in the graphic is a hybrid 4:1 voltage balun / 1:1 current balun from BalunDesigns (IIRC model 116t) – 73’s WB8LZR
Added 12/24:
With the original loop, I had a piece of ladder line between the balun and the wire of the loop. It was changed to various lengths, and finally I settled on 42 feet, the latter of which worked well and avoided the quarter wavelength multiple problem. The SWR at 7.075 MHz was 1.0, and I had less than 1.5 to 1 SWR without using a tuner on all bands higher than 80 meters except 30, 17 and 12 meters, which would be expected. The SWR on 10.120 MHz was 2:1, on 18.075 MHz it was 3:1 and on 24.9 MHz it was also 3:1. I could tune all of those warc bands (1:1) with a tuner, and had QSOs on all those bands using the loop antenna. But, in the final analysis I removed the ladder line altogether as it seemed to make for more noise.
The ladder line was light and easier mechanically to attatch to the antenna, allowing the heavier balun to be attached to a tree. However, I ended up with the balun actually on the antenna, and like the results better. The SWR for all bands remained unchanged (or changed by less than .1) after the removal of the ladder line. I have the balun secured with its own lanyard.
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.
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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.
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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).
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
Figure 1: The 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.
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.
Figure 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.
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/.
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.
WB8LZR 