[ARC5] Looking for miscellaneous ARC-5 parts

[Bill Cromwell]

Hi Charles,

Looking at the part where you advanced the B+ slowly I am guessing the 
receiver has not been recapped. The receivers run very well on reduced 
B+. Some run as low as 60 volts and others say the sweet spot has been 
160 volts for them. I have settled on 90 volts. The radio runs cooler 
and from a cold start mine are ready for work in under a minute of 
warmup. Reduced B+ is easier on the antique caps, too. So of mine have 
been completely recapped and others still have some of the original 
caps. All of them have the same low current draw.

Your transmitters will not make designed power on reduced B+ but you 
probably already know that.

73,

Bill  KU8H


On 02/28/2015 05:49 PM, Charles wrote:
> I just acquired a Navy (ARA) 3-6 Mc. Command Set receiver. It’s missing the removable cover plate, and some idiot had yanked off the nameplate and drilled holes in the (fixed) top cover so he could diddle the front end trimmers without removing the cover first. Lots of other sloppy hacks including a phono plug on a pigtail hanging out of the side, unshielded wires running the length of the chassis that connect the detector and the grid of the audio stage, an octal socket on spacers where the dynamotor plug used to be, and filaments rewired for 12 volts. So I had to clean all that up first (including a cold solder joint in one of the filament connections).  I let it warm up for a few minutes, then brought up the B+ a little at a time in case an electrolytic needed reforming. The magic smoke stayed inside all the components up to 200 volts.
>
> Nothing from the speaker, but touching the grid resistor of the 12A6 resulted in a hearty buzz. So far so good. All tubes warm to the touch. Naturally he’d managed to misalign it so badly that there wasn’t even any “hiss” from the speaker and it was as sensitive as a brick, not to mention 200 or more KHz off on the dial. Surprisingly, once I applied a signal generator and did a quickie alignment at 4.000 MHz (using the extra holes), it perked up a lot. Retuning the IF cans slightly helped even more. Now I just need to make another plate for the front opening to hold the phone jack, gain and IF regen pots (previous owner had installed a toggle switch where the 3 uf cap used to be, and used dry-transfer lettering for “AM” and “CW” which looks half decent).
>
> So, I’m looking for a matching (black wrinkle) top cover without the gaping holes and with the tube cover...
> If none are out there, just the removable cover would be great. I could make one from sheet aluminum easily enough, but don’t have the snap latches. E-clips would work but don’t look “right”.
>
> As mentioned, the dynamotor plug is missing and I’d like to re-install one, but it looks like he enlarged the hole somewhat (and I don’t have a spare dynamotor either), so I may just run it on a power supply instead and not bother trying to un-hack the plug...
>
> Finally, I’m still looking for a transmitter bottom plate.
>
> The sheet metal seems to be the first thing discarded when hams start modifying them... it’s very frustrating (and probably even more so to collectors who want them completely original).
> Thanks for any help.
>
> -Charles
> WB3JOK/0
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