I used a 580 Delta for years and loved it! Like you, I like to operate with
the RF gain. Since it didn't have one I used the On/Off function of the
volume control (which is pull on/push off, I believe) to operate a DPDT
relay I installed inside the 580 in the area of the 20 dB attenuator switch
(which is located on the back panel!) Basically, the contacts of the relay
were wired in parallel with the switch if I remember correctly, so you won't
be undoing much of anything besides borrowing the power switch. Plenty of
room in there for a little Aromat DPDT PCB relay.
Power on and off was then controlled by the switch based circuit breaker
that TenTec supplied.
It was a great work around and the radio was excellent besides missing that
one feature. The 20dB atten was just about right most of the time when I
needed to cut down on overall gain, which for me, was most of the time. It
was probably "on" more than off. I operated CW mostly on 80 and 40 meters
doing traffic handling in the evenings.
Hope that helps.
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