old test equipment found

From: Gary Hildebrand <ghldbrd_at_ccp.com>
Date: Tue Nov 26 11:43:01 2002

Carlos Murillo wrote:
>
> I've recently come across three pieces of vintage test
> equipment;
---snip--
> The Heathkit audio analyzer passed visual inspection
--snip--
> The Precision signal tracer is not working; somebody took off
> the rectifier tube/valve and soldered a couple of diodes; I suspect
> that at least one filament is open (pins 3 and 4, right?
--snip--
 The Radiometer Copenhagen gear I haven't powered up

> Now the question: can you please take a look and see if
>
> 1) you have docs for any of these,
>
> 2) might guess what the operating procedures are and what the controls
> and connectors are for? Some I can guess, others I don't know.


The Heathkit distortion analyzer used to be fairly common around AM
radio stations, as they used it for proof-of-performance testing. One
feeds an audio tone into an amplifier/console and the Heathkit is across
the output. Null the tone out, and what's left is harmonic
distortion/noise/hum etc.

The precision signal tracer is not much more than a very high gain audio
amp. The missing probe is just an AM detector, so that a modulated RF
signal can be followed in a radio. I'm wondering if those diodes are
replacing a 6X4, 6X5, or 5Y3, as the pins vary. If the tubes are all
6xxx numbers then it is tranformer operated, if they are different
numbers, it may be series string across the AC line and not worth
fixing. I've found them not all that useful, just makes troubleshooting
AM radios and audio amps a lot faster.

The Beat Frequency oscillator looks like a copy of a GR design. I think
all it may be is an audio oscillator on the order of the venerable HP
200CD, with variable output impedances.

It will be a good exercise of the grey matter getting them restored w/o
schematics. There might be info on the Web for those units, so keep
looking.

Gary Hildebrand
St. Joseph, MO
Received on Tue Nov 26 2002 - 11:43:01 GMT