Brian,
Also keep an eye on published SSR on/off switching times. On my QRZ.com
page, you can see two keying interfaces about half-way down the page. One
uses a balanced pair of IRF820 MOSFETs to switch AC and DC loads. The
other uses a power MOSFET SSR block that switches substantially faster than
that shown on the Ixys datasheet. Both types quickly switch high-voltage,
high-current loads in approx. 1-2 mS.
http://ixapps.ixys.com/DataSheet/CPC1978.pdf
The IRF820 version is an adaptation of Chuck Olson's "KeyAll," with some
added logic options.
http://wb9kzy.com/keyallhv.htm
I highly recommend Chuck's kit and it will fit nicely into your 30L-1.
Although you can add it externally, it should be possible to add it
internally in a way that's 100% reversible in the event you later want to
sell the amp. Most Collins collectors are looking for unmodified gear. The
Keyall comes with a PC board and all parts for about USD $15.
I think the simplest and cheapest option has already been discussed by Jim,
W8ZR. It's tough to beat the Ixys PLA140 or the Avago series of balanced
MOSFET SSRs. Add one resistor to limit photodiode current and you're done
-- although you'll need to build it on something like Vector/perf board.
Just ensure the 30L-1's internal relay doesn't get near the 1/4 amp
switching limit of the device.
Paul, W9AC
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