On Fri, 11 Sep 1998 14:39:40 -0400 km1h writes:
>
>On Fri, 11 Sep 1998 10:46:56 -0700 "Radiodan W7RF"
><RFpower@radiodan.com> writes:
>>
>>Hi Dick,
>>
>>For specifics on the NCL2000 I'm sure that Carl KM1H who was on the
>>development team for that amp in 60's will give you (and hopefully
>all
>>of
>>us) some interesting tid bits on this classic.
>
>
>And I opened my big mouth before your msg appeared Dan !!
>Tnx for the NCL-2000 plug.
>
>I have my own procedure for testing and reforming electrolytics. It is
>strictly used by what was available at the time and I would like to
>see others post their versions.
>I use an antique Oregon Electronics PS that allows full variables of +
>and - zero to 500VDC @400ma simultaneously along with a seperate up
>to 6.3V 16A filament supply .
>I found this gem at a hamfest years ago that was put on by a mind dead
>FM repeater group...paid $5.
>
>I re-form caps by slowly advancing the DC while watching the current
>meter. There will be current spikes that will quickly settle down to
>the microamp level with good caps. Slowly advance the voltage while
>watching the current...it takes patience at times. Once you are up to
>the rated voltage let the cap cook for a few hours or so....I have
>found some caps to fail after an hour of full voltage...the feel test
>is often best...if its hot... its junk.
>
>As a Navy Tech I learned the "follow your nose" method of trouble
>shooting and can also recommend Dans comments below; I just dont have
the patience with caps as I do with expensive tubes!
>
>73 Carl KM1H
>Amplifier Repair and 6M Conversions Our Speciality
>National Radio 1963-67
>
>
>
>>
>>As far as reforming old caps and a general power up of old equipment
>
>>goes, I
>>have some procedures that I go through.
>>I too love the old gear and have over 60 old ham rigs and amplifiers
>
>>(26 of
>>which are SWANs) and deal with this often.
>>
>>Your 120 VAC variac will do nicely for the initial stages, although
>>it's
>>nice to slowly continue up to rated input voltage. You probably can
>>compensate for this by leaving it on your highest voltage (at the end
>
>>of the
>>procedure) for a longer time.Unfortunately you won't be able to
>slowly
>>go up
>>to the rated voltage and that would safely let you see if the high
>>voltage
>>produced will cause a flash over at some weak point (physical or
>>electronic).
>>
>>A case disassembly and visual inspection are the first things. Then
>>clean
>>switches and tube sockets and pins.Your visual inspection should be
>>backed
>>up with measuring any components that look suspect. Replace anything
>
>>that
>>looks or measures bad. Don't overlook the AC line cord!
>>Personally I leave the case open when I bring up the voltage with my
>
>>variac
>>so I can see anything that sizzles or smells or burns. Usually this
>is
>>not
>>the case as I start with a very low voltage (normally 10% of rated)
>>and
>>always use an AC current meter in line with the variac so I can see
>>what
>>current is drawn at any particular voltage level.
>>I warn you, that if you don't feel safe doing this or others may have
>
>>access
>>to your work area then reassemble the case!
>>Patience is your best friend. There is NO disadvantage to going slow,
>
>>only
>>going too fast!
>>
>>I use 10% for 6 hours, 20% for 6 hours, 40% for 12 hours. Usually
>>after this
>>I can go faster and many times just use a few hours at higher
>levels.
>>Obviously the times are approximate and you can go longer if you
>like.
>>I don't know if there is a scientific procedure, but I'm sure there
>>are
>>varying opinions.
>>
>>This works for me
>>
>>73, Dan Magro
>>Radiodan W7RF, Portable Clinic
>>High quality Henry Radio RF Power Amplifiers for LESS!
>>New, used, unusual, classic radios, accys & RF POWER!
>>http://www.radiodan.com RFpower@radiodan.com
>>A trip to our web site is worth the click!
>>
>>-----Original Message-----
>>From: Richard Carroll <w0ex@scan.missouri.org>
>>To: amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
>>Date: Friday, September 11, 1998 9:53 AM
>>Subject: [AMPS] Question on reforming caps NCL2000
>>
>>
>>>
>>>I have just acquired a very nice old
>>>National NCL2000 amp (along
>>>with the matching NCX5 transciever &
>>>NCX-A supply ) that
>>>hasn't been turned on in about 20 years.
>>>I intend to bring it up
>>>slowly to reform and avoid shock to the
>>>old power supply electrolytics.
>>>I have a 120vac variac, but none for
>>>220, and I believe this should
>>>work out OK, but what are the "gotchas"
>>>involved? I feel that I should
>>>remove the tubes as a precaution against
>>>any possible damaging flashover.
>>>Any suggestions from those who are
>>>familar with this amp? Also
>>>any loose 8122's around and available?
>>>I'll want some spares if I keep it.
>>>
>>>Dick W0EX
>>>
>>>
>>>--
>>>FAQ on WWW: http://www.contesting.com/ampfaq.html
>>>Submissions: amps@contesting.com
>>>Administrative requests: amps-REQUEST@contesting.com
>>>Problems: owner-amps@contesting.com
>>>Search: http://www.contesting.com/km9p/search.htm
>>>
>>>
>>
>>
>>--
>>FAQ on WWW: http://www.contesting.com/ampfaq.html
>>Submissions: amps@contesting.com
>>Administrative requests: amps-REQUEST@contesting.com
>>Problems: owner-amps@contesting.com
>>Search: http://www.contesting.com/km9p/search.htm
>>
>>
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