Make SURE you size your TX / Rx relay correctly.

[KD6VXI]

Friend send some pics.  Thought I'd share.

He runs legal limit AM


Size your gigavac right.  This was NOT a cheap fix.

--Shane
WP2ASS / ex KD6VXI

[KD6VXI]

Yes.  The first pic of the inside of the relay, that's Cload next to it.  Sized appropriately.....  Peak currents are in the range above 75 amps on that cap.



--Shane
WP2ASS / ex KD6VXI

[KD1SH]

Is he sure it wasn't a sequencing issue - hot switched it?

[KD1SH]

I'm using a Greenstone VC-2 in my 8877 two-holer; specs say 50 amps. It's enclosed in a Budd die-cast box, so at least the shrapnel will be contained.

[W3SLK]

I'll bet that will keep your panfish down!

[KD6VXI]

Is he sure it wasn't a sequencing issue - hot switched it?

He uses a foot pedal for the amp and a microphone for the radio.  I do believe his amps are sequenced, I know there is more than one stage but I only saw one foot pedal.....  Didn't get into it that close / behind the scenes, other than the amplification room.

I wondered about balanced currents in the configuration used.  I would have preferred symmetric but that's a tall order for 4 vac relays that large.

--Shane
WP2ASS / ex KD6VXI

[KD1SH]

Probably almost impossible to ensure balanced current through multiple relays; even less possible to ensure perfectly simultaneous closing/opening. I'm only using a single vac-relay for the output switching,  but I designed my sequencer to be almost painfully slow to make sure that everything is settled down before the final application of operating bias brings the tubes out of cutoff.

[Opcom]

Handles noted.

[KD6VXI]

Handles noted.

8 handles.

4 pairs.


--Shane
WP2ASS / ex KD6VXI