[ARC5] Frequency Standard

[David Stinson]

----- Original Message ----- 
From: "Leslie Smith" <vk2bcu at operamail.com>
Subject: Re: [ARC5] Frequency Standard
Thanks for writing, Leslie.

> In particular I'm interested in how you use 
> the TBX frequency standard...
It is, in effect, a small, portable, fixed-frequency
version of an LM or BC-221 frequency meter.
Uses one "D" cell and one 7-volt bias battery,
for which a 9-volter works fine.
A single-tube (one of the 3-volt mini pentodes 
with the center-tapped filament, don't remember
which at the moment) is wired as a crystal 
oscillator with an antenna input port and 
an audio output transformer for headphones.
I use the oscillator function to net the receiver
to the crystal, then key the transmitter and 
listen in the headphones. The transmitter
signal beats with the crystal. 
Zero-beat and you are netted to the 
crystal frequency. This is far faster and easier
than setting-up an LM/BC-221, or even 
a modern freq standard and freq counter.
One does need crystals, of course,
but most AM operation around here centers
on three frequencies so it's not two troublesome
to get crystals for those.

> So - what other test gear do you use on the bench?
> What do you (and other group members) see as 
>he MINIMUM test gear to adequately service these sets?

First- I have some rules for test gear:

1. Learn how your test equipment works.
Primers are available on the net.
Guessing leads to regretting.

2. Test leads and probes must be good quality.
Cheap, crappy test leads and probes break 
when most needed and can crack, exposing
you to whatever high-voltage you're probing.
And worse- bad leads and probes will lie to you.

3. Regularly check your test gear for acceptable
calibration and operation.

4. Once you have established 1, 2 and 3 above,
BELIEVE your test gear. Can't tell you how
much time I've wasted because I just didn't believe
what my test gear was telling me.

Also-test gear needs to be of decent quality.
Old kit-built scopes and Radio Shack meters
are unreliable and they lie to you.

My list of indespensible test gear:
1. Oscilliscope.
2. Digital Multimeter.
3. Analog Multimeter (better then digital in some apps).
4. ZM-11 LRC bridge, used for testing/forming caps.
5. Frequency standards / signal generators.
6. General coverage receiver.
7. Variac
8. Dummy loads / Phantom antennas.

Additional items that make life easier:
Variable low- and high- voltage DC supplies.
Frequency counter.
Antenna analyzer.
Audio signal generator.
Audio/RF signal tracer.
Watt meter / Reflectometer
A good sweeper would be a treat, too.

73 DE Dave AB5S

P.S. Keep the batteries in your digital test 
equipment fresh.  Low batteries will give
misleading indications.  Learned the hard way.