Specifications

If you wish to do this mod, you will have to consult others that have done it, or figure it out
for yourself. The mod is not difficult for a technician with good radio knowledge &
experience in amplifiers.
If you can't do the mod, contact someone to do it for you, but don't expect the work to be
FREE!
The parts you will need are a pair of Jennings RJ-1A vacuum relays or equal type, for about
$45 each. You need hardware to mount the relays too.
The exact mod I did to my unit is proprietary so, I will not discuss it in any great detail.
Another method of repair of the PIN diodes, is to acquire a new set of diodes of much better
dissipation, and install them. High power PIN diodes of this type are not cheap!
Fig.1a shows the original PIN diode set up, the letter "A" points to the destroyed diodes.
Fig.1a
QSK?
In doing my vacuum relay modification, some would say that I have lost full QSK capability. I
say I have not. The PIN diode system has a maximum switch time of 4mS, good for about
50wpm, while the vacuum relays have a switch time of 6mS, or about 40wpm.
I ask this, how many hams do you know that do 50wpm full QSK at 1500 watts? How many
do 30wpm or even 20wpm? I think that far fewer do it, than do, and even fewer use legal
power. Going from 50 to 40wpm capacity is not a very great loss. I don't even use a power
amp when I do CW, so it is no loss at all to me. I guess the true hardcore high power full
QSK CW op will need the fastest PIN diode system available, but it's not going to be cheap.
The vacuum relay system is more that adequate for SSB VOX operation, or AMTOR.