[ARC5] Backwave

[Bill Cromwell]

Thanks Mike,

The selector relays in the transmitters clunking once at power on or at 
band change wouldn't bother even me. Since the rest of the relays are in 
external control boxes - and mine would be home brewed - those can 
contain anything I want and could be keying transistors (silent). It may 
be old hat to most everybody else but this is the clearest picture I 
have to date. Now my interest is increasing.

I have the manuals in PDF files here. I have only used them to hunt down 
original info for the receivers. Now I will dig out the info for the 
transmitters. I suppose now I will have to find a couple of transmitters.

73,

Bill  KU8H


On 10/26/2015 11:19 AM, Mike Morrow wrote:
>> If one has not disconnected the antenna relay, then surely that is
>> quite noisy and unacceptable. But the selector relay makes very little
>> noise in my experience.
> But...*both* relays [K-53 (MO HV and PA cathode) and K-54 (Antenna terminal)] in these transmitters are SELECTOR relays and are NEVER keyed in the original design.  Both remain energized, even when receiving, as long as the transmitter select switch on the transmitter control box is positioned for that transmitter.  Thus, there are NO keying noise issues from the transmitter.
>
> On key-down, K-52 (HV keying) in the modulator, and K-55 (Antenna switching) in the antenna relay unit energize.  Also, in the typical three-receiver rack, all three relays (K-1, K-2, K-3) energize to switch the AF busses from receiver AF to modulator sidetone AF.
>
> Thus, in the typical two-transmitter and three-receiver command set, five relays respond to key or PTT operation.  None of them are in the transmitters.
>
> This is all old often-covered stuff of little interest to most hams.
>
> Mike / KK5F
>
>
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