[ARC5] BC-453 Question BC-454 Also

[Mark K3MSB]

KB8TAD said " replacing them with tiny new caps using the original wires
wherever possible, mounting the new pieces on the unique little terminal
strips in the center so that the restoration could be reversible if I
decided to restuff the little pots in the future "

This is what I do;  the leads may be a bit longer but the original wires
are preserved.   All reversible.

I don't bother measuring the current.  The old caps get replaced shot-gun
style.   They're cheap and it doesn't take very long.   I keep the original
flower pot caps in a marked bag so I can restuff them (if I'd ever want to
do that)  or provide them to the radio's future owner.

Ask N people about cap replacement and you'll get N+1 responses.....

73 Mark K3MSB




On Fri, Apr 3, 2020 at 2:59 AM Rich Post <kb8tad at gmail.com> wrote:

> Hi Scott,
>
> Your mileage will vary.  I recently brought a couple of these back to
> life.  I had acquired an ARC-5/ R27 and a Navy ARA CCT-46104, roughly
> equivalent to the R-24.  Both very unhacked.  The R-27 still had its
> dynamotor.  I used a variable regulated B+ to power each with the 24 volts
> of filament supplied by a separate transformer.   Gently raising the
> voltage up by way of the variable supply, the R-27 powered up unmodified
> right to 250 volts at a measured 48 mA.  Very little is to be gained from
> these beyond about 130-150 volts DC.  I had to turn the volume down even
> with a B+ voltage of only 150 VDC at a draw of 27 mA.   I decided to leave
> the R-27 in its good working unrestored condition, operating it at that
> reduced voltage.
>
> The ARA, on the  other hand,  was already drawing 50 mA at only 50 volts.
> I throttled the voltage back so that the set was only getting 25 mA. After
> a few minutes, I was surprised to be able to crank the voltage up to 135 at
> that 25 mA but the magic didn't last.  One of the potted cap sections
> decided to become a 700 ohm resistor.   I replaced that cap section and
> powered it again, measuring the voltage on each of the cap sections and
> disconnecting all that saw more than 6 volts, replacing them with tiny new
> caps using the original wires wherever possible, mounting the new pieces on
> the unique little terminal  strips in the center so that the restoration
> could be reversible if I decided to restuff the little pots in the future.
> After the cap replacements, the ARA ran at the same 250 at about 48 mA or
> my B+ preference of between 130-150 volts.  I tried several solutions for
> the B+, ending up building a voltage multiplier off the 24 VAC filament
> supply.
>
> I have a couple of already hacked "Q-5'ers" that need to be revived.  Time
> for some more experiments.
>
> 73 de Rich KB8TAD
>
> On Thu, Apr 2, 2020 at 11:27 PM Whitebear1122 <whitebear1122 at comcast.net>
> wrote:
>
>> Today I brought in from the garage a BC-453 that has been sitting out
>> there for several years. It has been sitting in an old timers basement
>> since the early 60’s so it was gunky with grime.  So I had to clean it up
>> before I wanted to get to close to it..  It cleaned up nicely with some
>> GOJO and a tooth brush, and looks great.
>>
>> I’m thinking of building a Q5’er with it.
>>
>> Question for you experts:  How would you approach powering this up? One
>> option is to just plug it into a variac and slowly bring it up and find out
>> what happens.  Another approach would be to disconnect all the 0.05 or 0.5
>> cans and measure capacitance and leakage current.  Another approach is to
>> shot gun replace those caps.
>>
>> I know there has been a lot of discussion about recapping the BC-348
>> Micamold caps and just getting it over with.   What about the ARC5
>> receivers?  What has been your experience?
>>
>> Thanks, Scott WA9WFA
>>
>>
>>
>>
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