Heathkit Apache

[analogee@gte.net]

Another Heathkit Fanatic wrote:

> Then I saw one of the 5r4's blink and the fuses popped.
> About an hour later I traced the trouble down to a .001mf 2kv cap
> that went short. It's the one on the input of the plate choke, I don't
> seem to have one on hand to replace it with, so I just removed it


Dear "73" Dave and James D. Mayfield:

I've got all the answers regarding your blown transmitter capacitor.

Send me your street address, and I will send you a shiny-new .001uF 3kV
ceramic disc capacitor, on-the-house.

Never seen your particular radio, but there are always two categories
of parts in an engineer's design:  "Mandatory" and "Optional".

The Mandatory parts are the ones where you cut it loose and the
radio stops working, or smoke pours out.

The Optional parts are the ones where you cut it loose and everything
seems to work just great.

Most equipment designs have quite a lot of optional parts...

Unfortunately, unless you talk to the original engineer, you might be
mistaking an optional part for a mandatory part.  Under certain
circumstances (a certain gain factor in a tube, or a certain
temperature) the part might be necessary.  It might also be that the
part improves overall performance (cuts spurious sidebands down, or
reduces audio distortion, etc.) and you just aren't aware yet of the
degradations that are occurring with the part removed.

That is why, if the original design engineer is not available for
comment, we should maintain the equipment to original specifications.

I have your capacitor sitting on my desk.  It is new, with long leads,
and rated at 3kV.  I also have a .001uF / 15kV available, but it is
larger and cost me lots of money.  Also if the 2kV unit blew, 3kV ought
to avoid future troubles.

It came from a company called "Mouser".  They are sitting on the fence
somewhere between wholesale and retail.  You can get a catalog if you
give them a (fictitious) business name, and call 1-800-346-6873
http://www.mouser.com

They have parts such as this high-voltage cap.  Digi-Key
(1-800-DIGI-KEY) is also a company that has abundant parts, pretending
to be wholesale, but charging prices well above retail.

Good Luck!

- Norm
  analogee at gte.net

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