Fixing Stuff: First up – 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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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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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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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

butterworthon-16dip-soc-6

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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SoC/SBC Boards for Ham Radio

audio-gameplan4

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:

https://programmingmiscellany.wordpress.com
(The link goes to another of my blogs)

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