Terry wrote:
"coffelt2" wrote

Anyway we were talking about how the linear improved the transmit signal
strength, but did nothing for the receiver and he wanted to also build a
small receiver preamp to put inside the linear cabinet, and we both got
the samw brainstorm, at the same time. Why not wire the linear up so it
would work in BOTH directions? I suppose a grounded grid preamp using
tubes with a combined plate dissipation of some 300 watts seems crazy,

Try 1000 watts for the combined plate dissipation.


The 572B actually had only 150 watts plate dissipation and the SB200
used two of them. The T160L version of this tube had a 160 watt plate
dissipation. Many SB200's grossly overloaded these tubes and got away
with it.

and one's first though would be "you'll blow up the receiver!".

Just wait until it goes unstable and oscillates. Bye-bye receiver!


The odds of a pair of 572B's in grounded grid oscillating were very
slim, at least at HF. VHF parasitics were another story, but the SB200
was well built in this regard. I'm sure the rig was stable even without
an antenna connected. IIRC we thought of putting in a pair of back to
back 1N4007's on the rig side during receive just in case.