[Amps] Speaking of PIN T/R switches

[Peter Chadwick]

The main point about the PIN diode is that you need a long carrier life time - 5 to 10 microseconds is good for 160m and up. I STRONGLY recommend reading the application notes at Microsemi.com - that tells you nearly all you need to know about PIN diodes and their applications.
I have used 1N4007s as PIN diodes, but you need to be a bit careful on the manufacturer, because some of them are faster than others, and as a result, don't 'PIN' too well. I found that they weren't too reliable long term at 100 watts, though. Bigger power rectifiers could well be quite good, although the problem then is the 'OFF' capacitance of the device.
The principle of the PIN is that because of the long carrier lifetime, when the RF signal reverses polarity, the current keeps flowing - that's why there's a lower frequency limit.
I have some devices for 'one day use', rated at 1 amp forward current, 2kV reverse volts, stud mounted and about 10 microsecond carrier lifetime. One day.....I hesitate a bit, because I prefer to arrange the amplifier so that when in receive, the antenna relay is actuated. This means that when the station is off, any lightning induced surges down the coax go to a high voltage rated device - the tube - and hopefully not into the rx front end. Remember that lightning over here is a LOT less severe than you get in the US......
73
Peter G3RZP