Phantom amplifier 10 tube

[BlowinSmoke]

I mean isn't really dumb to switch the HV secondary of a transformer to turn on HV to a tube in transmit and even dumber if you switch the HV DC voltage. I don't know of any small ice cube type relay that is rated higher than 250v ac.

 

[Dmans]

I mean isn't really dumb to switch the HV secondary of a transformer to turn on HV to a tube in transmit and even dumber if you switch the HV DC voltage.

How does YOUR design work?

73’s
David

 

[BlowinSmoke]

How does YOUR design work?

73’s
David

My design? I am sorry but I can't take credit for the design because the "design" has been around for many decades before I was even born. But the "design" which is acceptable through the thousands of um, ham amplifiers, is actually quite simple. The tube(s) are biased to cut off using a cheap resistor keeping HVDC on the plates of the tube(s) all the time. When the amp goes into transmit a relay, much like the one which switches high voltage switches out the resistor and the tube is ready to transmit. The relay doesn't take anywhere near the beating it takes switching HV ac.

 

[nomadradio]

The blown capacitor is just that, a bad part. They used 1000-Volt parts with 950 Volts DC on them. Not unusual to see them fail.

Since you have continuity through the relay's coil, the relay is probably not at fault. This makes it sound as if maybe the center contact of the antenna relay is not closing the circuit to activate this relay. If the relay's coil shows continuity, it's not blown open.

Checking the contacts closely on the antenna relay is an awkward proposition, but it sounds as if this may be what is preventing the HV relay from activating when you key the mike.

73