Solar CDX

Winterfest 2012

SA-2040 tuner: two big capacitor knobs, one central roller inductor knob, a turn counter and a knob to select output

At the end of February, the Vienna Wireless Society held its annual hamfest, Winterfest, and this partially accounts for my absence of blog entries in recent months, as I was coordinator for the event. We had more than 100 vendors in our indoor area, another 40 in our tailgating space, and about 700 people were attracted to the event. I could go on at length about the event, and maybe I will at some point, but for now I’d like to post about the items that I picked up at the event. I’ve mentioned my acquisitions to a couple friends and want to show some pictures.

As soon as the event opened, my eyes landed on a Heathkit SA-2040 Tuner. I have an LDG AT100Pro automatic tuner and it does a great job, but for the Collins gear, I wanted a fully manual tuner. The automatic tuner makes excursions in and out of good match, and I just don’t want to subject the finals of the S-line equipment to variable and out-of-range vSWRs. I’d rather map out the setting for the band segments that I use and then manually adjust.

I had, in fact, been looking for a few months at several models of manual antenna tuner on ebay, eham, and the other usual places. The SA-2040 was high on my list. Typically they run over $100, plus shipping. When I found one at Winterfest, I was happy to see that it was less than $100, in good shape, and already had the modifications that I was considering — a knob with a thumb wheel on the roller inductor, a switch to select multiple coax outputs, and a switch that takes the input to ground. I had a lot of administrative work to do at Winterfest, so I bought it as soon as the event opened and stuck it in my car for the day.

An overhead shot of the internal workings of the SA-2040

When I got home, I took a look inside it. Truthfully, when I got home, I crashed on the couch for the day and didn’t get around to looking inside the tuner for a few days, but either way, I did look inside, and saw that it’s in fine shape. The roller inductor and capacitors are heavy duty and in pristine condition, with no evidence of arcing. The modifications look solid, and I couldn’t spot anything troubling. I screwed it back together and then started trying to figure out how I could possibly fit it on my bench.

The SA-2040 does not have an SWR meter, so I needed one. Luckily, I had ordered one several months ago from Ten-Tec as a kit: the 1225 SWR/Wattmeter. I had a good experience putting together the model 1320 QRP transceiver from Ten-Tec, and it has held up well as I’ve lugged it all over the world making contacts. The SWR kit was also a first-class affair — packed well, parts grouped meaningfully in several bags, all parts present with appropriate excess on wire, and a great manual. The wattmeter consists of a metal cabinet, a large cross-needle display, a range switch, and the option of average or peak-reading for both forward and reverse power.

Front view of the TenTec 1225 wattmeter, with meter illuminated in blue

The organization of the manual was excellent, with the usual check it and then check it again double column for checking off completed steps. There was no ambiguity in the instructions, all the landmarks were obvious, and I didn’t need to do any sort of clever interpretation or fall back on the internet to find exceptions, modifications, etc.

Calibration requires no equipment beyond a digital VOM. One trimmer pot controls internal reference voltage, and other pots are used to set the forward/reverse fudge factors for each power range. Having built the WM-2 QRP watt meter, I’d say that this one was slightly easier to calibrate. This SWR meter was a more complex build with more parts and more mechanical connections, but that is commensurate with its additional features (and I’m certainly keeping the WM-2 as well).

So, the 1225 Wattmeter was assembled over the last week and is now inserted inline between whatever rig I’m using (the first coax switch) and whatever antenna is selected (second coax switch). One fun feature of the 1225 is the RGB backlight, which can be adjusted to any color with trimmer pots. I’ve set mine to a dark blue.

TRS-80 model 100 and manualThe other item I bought was not radio equipment. Near the end of the hamfest, I walked by a table and saw a TRS80-Model 100 “laptop” computer. I’ve always thought this computer was way ahead of its time, and that it represented an important milestone in engineering, so when I saw one marked down to $50, I bought it.

This computer is powered either by wall wart or four AA batteries, has a full keyboard, boots instantly, and has a number of I/O ports including an RS-232 and the venerable S100 bus. I verified that this one is fully operational. I’m not sure exactly what I’ll do with it, but I think it was a good purchase.

 

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