[ARC5] ARC5 CW Question

[J Mcvey via ARC5]

OK, I see what you mean now. Initially I thought that since K53 was supplying osc B+ and final cathode ground the transmitter would be active. Since the transmitter relay K54 and K53  were on the same select line, I thought that they would be clacking away with each tap of the key. ( that's how it is in the You tube video, too).

After looking closely, I see that K54 and K53 remain engaged while the transmitter is selected. The keying appears to be done in the MD7 by supplying the OSC and final B+ via K52  . I find it strange that they run the oscillator with no regulation right off the dynamotor and a dropping resistor and used a a regulator on the screens, but I guess it must have worked OK... Does K52 suffer from burned contacts alot?


In summary, the only relays that should be clacking when keying is the antenna relay in the BC442 antenna switch unit and K52 in the MD7. Is this correct?





On Sunday, June 22, 2014 5:20 AM, AKLDGUY . <neilb0627 at gmail.com> wrote:
 


I had never heard of a Lucy. She must be a sister to the Gibson Girl  (-;

http://en.wikipedia.org/wiki/Survival_radio

73 de Neil ZL1ANM


On Sun, Jun 22, 2014 at 4:44 PM, WA5CAB--- via ARC5 <arc5 at mailman.qth.net>
wrote:

> As Mike already wrote, no.  I'll add that the antenna relay he mentioned is
> the one in the BC-442, not the one in the transmitters.  The relays in the
> transmitters are transmitter selectors.  As you rotate the channel selector
> switch on the BC-451, you energize the two relays in one transmitter, and
> they stay energized so long as power is on and you don't change the channel
> selector.
>
> The system operates in full break-in mode (the transmitter dynamotor runs
> continuously in CW), which means that as you are sending, the receiving
> station can interrupt you by simply holding down their key periodically
> until you
> pause.  Civilian rigs very seldom have this capability.  The "delay" you
> mentioned prevents break-in.
>
> Robert Downs - Houston
> wa5cab dot com (Web Store)
> MVPA 9480
>
> In a message dated 06/21/2014 19:00:45 PM Central Daylight Time,
> arc5 at mailman.qth.net writes:
> > I was looking through the SCR274 manual, trying to figure out the
> > original control circuitry and realized that they used a boat load of
> relays!
> > It looks like there was a CW  "break-in" system of sorts, but I haven't
> > found a delay anywhere.
> > So, my question is: Do all of those relays have to engage very time you
> > hit the key?
> > If so,that's a whole lotta clacking goin' on!
> >
> > Jim
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