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Title: Make SURE you size your TX / Rx relay correctly. Post by: KD6VXI on January 19, 2023, 06:39:17 PM 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 Title: Re: Make SURE you size your TX / Rx relay correctly. Post by: KD6VXI on January 19, 2023, 06:42:00 PM 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 Title: Re: Make SURE you size your TX / Rx relay correctly. Post by: KD1SH on January 19, 2023, 07:58:31 PM Is he sure it wasn't a sequencing issue - hot switched it?
Title: Re: Make SURE you size your TX / Rx relay correctly. Post by: KD1SH on January 19, 2023, 08:16:00 PM 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.
Title: Re: Make SURE you size your TX / Rx relay correctly. Post by: W3SLK on January 20, 2023, 11:21:01 AM I'll bet that will keep your panfish down! ;)
Title: Re: Make SURE you size your TX / Rx relay correctly. Post by: KD6VXI on January 20, 2023, 09:07:54 PM 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 Title: Re: Make SURE you size your TX / Rx relay correctly. Post by: KD1SH on January 21, 2023, 09:21:18 AM 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.
Title: Re: Make SURE you size your TX / Rx relay correctly. Post by: Opcom on January 24, 2023, 01:22:25 AM Handles noted.
Title: Re: Make SURE you size your TX / Rx relay correctly. Post by: KD6VXI on January 25, 2023, 04:34:40 AM Handles noted. 8 handles. 4 pairs. --Shane WP2ASS / ex KD6VXI |