How 'bout a DX-20?

[wa1vwl]

A while ago, someone on the list mentioned they'd like to see the AT-1
transmitter revived. What I'm looking at is a DX-20 schematic. I though
about it and it might be possible. The idea is to use as many ready-made
components (generally available) as possible and forget about expensive
custom-made components. One of the obstacles would be the power
transformer. However today there are 120 to 240 volts AC transformers
available. You could use one of those to build a LV, HV and bias supply.
You wouldn't have to use a choke thereby saving money. You can still
find high voltage electrolytics. As for the filament supply, there are
still plenty of 6.3 and 12.6 VAC transformers around. OK, so you
wouldn't have just one transformer and the box would be bigger - maybe.
Or how about using an external supply. For example, a socket to accept
the Heathkit HP-23, or the Drake AC-4, or any other relatively popular
power supply that you may already have for example. For tubes, we could
choose any type that's not popular with the audiophiles. In other words,
affordable. Variable capacitors (50 pf for the oscillator, 150 pf tune,
840 pf load) would be a problem. We might have to get creative with the
1.1 and 2.5 mH chokes. Those are pretty hard to find and pricey. Of
course, we could cheat by reverting to toroids and save a bundle. That
leaves the .005 mF, 1.6 kV plate coupling capacitor. Anybody tried
tubular capacitors? I seem to recall someone in QST(?) trying something
like that in the past. I once tried to build some HV capacitors for a
trap antenna out of pc board material. It worked but it wasn't much
capacitance. Any ideas? The oscillator and final coil could be wound on
PVC tubing. Of course you would have to wind those yourself to cut cost.
As for the rest, I don't see too may red flags. Guess the only thing the
kit would need is a similar-sized and styled enclosure. And let's not
forget some plastic knobs. I bet it would be selling for a lot more than
$35.95 of 1960! So what would be a good target price?

Hope I stirred the pot.

73/Gerry/W1ID

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