[Milsurplus] ACR-5 Mobile

[telegrapher at att.net]

If you've got a 12V dyno and use 6V tubes in the receiver, won't that 
work?  I've bought receivers that had the 12V dyno's and loaded with 6V 
tubes.  What's wrong with that?.

Remember i didn't say anything about the transmitter or modulator, only 
the receiver.  Seems i recall seeing a write-up with a picture or two 
from way back showing an arc/SCR-274n setup in a car as a mobile rig. 
Don't remember any of the specifics but i suspect that there was 
considerable mod work done on it.  Either the receiver or transmitter 
rack which was a double unit had been sawed in half but that's about the 
extent of my memory recall cells.

Larry
W0OGH

Jack Antonio wrote:

> There are 12V dynamotors that will fit on the receivers with no mods, 
> but then there
> is the issue of filaments and all the relays in the receiver rack and 
> modulator. AFAIK
> there is no 12V dynamotor that will be a plug and play equivalent for 
> the modulator.
> (Although I suppose you could mount the 12V dynamotor for the BC-604/684
> on a DM-33 or DY-? base). I have heard stories about the relays being 
> rewound with
> the next size larger wire, the antenna relays have two coils, which 
> could be
> rewired to work on 12V, so there are ways to convert the set to 12V, just
> depends on how much alteration you wanted to do.
> 
> There was some mention on the web about a police department that converted
> SCR-274Ns to 12V(in New Zealand, IIRC), but no technical details.
> 
> My solution would be to try one of the newer solid state 12V to 120AC 
> inverters and
> use a regular 28VDC 20A power supply. Leaving the radio itself in stock 
> configuration.
> 
> As far as power out goes, on CW I've always been able to get at least 
> 25W out of
> a stock transmitter(using the stock dynamotor), but on AM the screen 
> voltage
> is lowered, which brings AM power down to 15 watts or so.  I can see why
> this was done on the SCR-274N with its screen modulation, but I guess when
> the AN/ARC-5 was being designed, higher AM power was just not a 
> requirement.
> Thinking about it, these were short range sets, 15 watts may have even been
> the maximum power the Navy wanted.
> 
> Jack
> 
> Jack Antonio WA7DIA
> scr287 at sbcglobal.net
> 
> 
> 
> Al Klase wrote:
> 
>> Troops,
>>
>> I'm starting to contemplate taking a stock AN/ARC-5 mobile so people 
>> can see and hear it.  This would be a single transmitter and receiver, 
>> probably on 75 meters, plus an MD-7 modulator, RE-2 antenna relay, and 
>> control boxes as needed.  I have all of above, but need a single 
>> transmitter rack and mount, MT-68/69.
>>
>> Does anyone know the actual output of the TX?  Manual sez 15 watts 
>> carrier, but I suspect a pair of 1625's with 550 on the plates should 
>> do at least twice that.
>>
>> Also, there the issue of primary power.  I'm looking for a good way to 
>> get 28 volts at about 10 amps from 14 volts with enough reserve to 
>> spin up the TX dyno.  I don't suppose anyone has 12/14 volt dynomoters 
>> for MD-7 and RX lying around?
>>
>> Any help or suggestions appreciated.
>>
>> Regards,
>> Al
>>
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