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.
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
>
>
>--
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>
>
--
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