I'm using an NE602 as a balanced modulator in a simple DSB transmitter.
The circuit is similar to that of the K2.
My problem is that in the course of debugging the TX, I've somehow
destroyed three NE602s. At first I thought it was voltage spikes
from the T/R relay, so I put a diode across the relay coil to knock that
down. Then I blew another one. Now I suspect that somehow the problem
is related to parasitics that I'm trying to eliminate in the PA: There is
an impednce transformer in the 602's output circuit that would look like
a big step up transformer to any RF that that nasty oscillating PA might
send back down to the modulator.

What do guys think? Is this a likely suspect? Anyone know of other causes
for this kind of 602 carnage? Stop me before I kill again!

73 from London
Bill M0HBR N2CQR CU2JL
http://planeta.clix.pt/n2cqr