[Amps] contact bounce

[John Lyles]

Don, k4kyv, wrote a good description of how he tackled sequencing, for old buzzard AM stations, in the following:
http://amfone.net/Amforum/index.php?topic=6211.0

Maybe something there that can be learned for amplifier switching. 
John 
K5PRO



> Date: Mon, 05 Apr 2010 12:16:45 -0700
> From: "Bill, W6WRT" <dezrat1242 at yahoo.com>
> Subject: Re: [Amps] contact bounce
> To: <amps at contesting.com>
> Message-ID: <e7ckr5pdvdikmehm9v5lskvbk53nqbsuib at 4ax.com>
> Content-Type: text/plain; charset=us-ascii
> 
> Maybe I'm swimming against the tide here, but all this discussion
> about speeding up or slowing down relays is missing the real
> underlying point: Avoiding hot switching the amp relays on both going
> to TX and returning to RX. The schemes I have seen so far only address
> the turn-on issue, not the turn-off one. 
> 
> This is not a problem of speed, it is a problem of proper sequencing. 
> 
> What should take place is this.
> 
> When going to TX:
> 
> 1. Key the amp relays, both of them (if separate relays are used for
> input and output)
> 
> 2.A few milliseconds later, key the transceiver.
> 
> When returning to RX:
> 
> 1. Unkey the transceiver.
> 
> 2. A few milliseconds later, unkey the amp relays. 
> 
> Done correctly, you don't have to worry about relay speed because the
> amp will never "see" any RF except when its relays are closed, thus no
> hot switching. Likewise the transceiver will never see an open load
> when transmitting. The relays could be as slow as molasses and the amp
> and transceiver would still be protected
> 
> Easier said than done, however. I am trying to come up with a circuit
> using only relays (no solid state logic), possibly using the relay's
> own contacts to switch in or out a capacitor across the relay coil,
> but I'm stymied so far. Some clever person out there will no doubt
> find a way. Please let us know when you do. 
> 
> 73, Bill W6WRT