From: Carl Strode 
Subject: Re: [drakelist] AC-4 Cap values

>
> Possibly, the original design of this power was slighted somewhat, by not
>
> including a choke in each of the two points I noted above. That would
>
> have produced a significant reduction in the capacitor surge current at
>
> turn-on. Chokes would also have been more effective in reducing the
>
> ripple you originally saw on the outputs.
>
> I'm naturally assuming, of course, that you do intend to reduce power
>
> supply outputs down to their specified voltage levels.
>
> I haven't intended to sound critical of your modification efforts 
> here, Carl.
>
> Moreso, I am critical that Drake didn't put choke filtered supplies in 
> this
>
> equipment. I would sure have liked my T-4XB/R-4B's AC-4 to have been
>
> choke filtered. (Guess they figured the cost of the choke, a place to 
> put it,
>
> and also a slight change in the secondary output winding in the power
>
> transformer secondaries would cost too much to add into the equipment
>
> price.
>
> Anyhow, and Meanwhile, back at the Ranch (as "they" say, somewhere)
>
> keep up the good work, and keep us posted.
>
> Bill Flowers K5VKL
>
> _______________________
>
> On Wed, 02 Mar 2005 20:37:21 -0800 Carl Strode  > writes:
>>
>> Carl Strode  made 
> an utterence to the
>> drakelist gang
>> ----------------------------------------------------------------------
>> I have completed re-capping the AC-4.
>>
>> After looking at the actual caps installed, and comparing it to my
>> supply of modern electrolytics, I have replaced the 40 mfd caps
>> (shown as 40 mfd on most schematics) with 33 mfd.
>>
>> The HV filter caps were replaced with 150 mfd 450 volt units. ( I
>> had a bunch of these laying around).
>>
>> Since my original late model AC-4 had a 100 mfd cap installed at C3
>> and C4a, and an 80 mfd cap installed at C4b, I decided to keep
>> everything simple and replace these with 150 mfd caps as well. I'll 
> save all
>> of my 82 and 100 mfd caps for some other project.
>>
>> The 150 mfd caps I have are circuit board mount types, with both
>> leads on one end. This made installation above decks a snap. I removed
>> the old caps, and then reamed out one of the holes used for the old cap
>> ____________ __________________ ________________
>
> When I was finished, there was essentially no ripple at all! only
>> about a tenth of a volt on the 650 and the 250 volt, and about 
> 0.2volts on
>> the bias supply. Oh yes, as usual nowadays, the 650 is really closer to
>> 700, and the 250 is about 290. When the power supply is switched
>> on, it thunks a bit harder than it used to, due to the lack of leaky
>> caps and the increased cap values. The supply is much stiffer than
>> before. Very little sag and absolutely no detectable hum.
>>
>> I guess this demonstrates that with brute force, we don't need no
>> steenkin regulators!
>> > ----------------------------------------------------------------------
>> On Behalf of Carl Strode  >
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> 
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>>
>>
>

----------------------------------------------------------------------
On Behalf of Carl Strode 
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