[AMRadio] Protecting receiver (was WTB: Coax relay, 110VAC, aux contacts)

[Bernie Doran]

forgot to say, I use all 28 VDC relays, they are cheap surplus and do not 
buzz.
----- Original Message ----- 
From: "Rob Atkinson" <ranchorobbo at gmail.com>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Saturday, November 19, 2011 2:16 PM
Subject: Re: [AMRadio] Protecting receiver (was WTB: Coax relay, 110VAC,aux 
contacts)


Hi Bernie thanks for this information on switching with a QRO rig.

73

Rob
K5UJ

On Sat, Nov 19, 2011 at 11:32 AM, Bernie Doran
<qedconsultants at embarqmail.com> wrote:
> yep: On closing the xmit switch, a DPDT, the plate relays are grounded
> through the second pole. The first control relays are tripped grounding 
> rx,
> operating mute circuits, shorting speaker, turning on the driver stage,
> transfering the antenna, starting the Hamsters running on the wheel,
> etc,etc. and also sending a signal to the plate relays to start them,
> after a very short delay, first plate relay applies 240 through dropping
> resistor then second relay closes appling full 240 to the plate xformer.
> On receive the plate relays drop almost immeadiatly, as does the plate
> voltage as there is still drive applied because of a small delay in the
> control relays, they have a nice fat capacator across the coils. The
> Hamsters head to the water for a drink!! There could also be a set of
> contacts on the antenna relay in series with the second pole of the DPDT
> switch to prevent plate operation if the antenna relay did not operate. I
> have not found that necessary as the xmter shuts down on more safetys than 
> I
> can count. It is a Gates BC1G.
>
>
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