On Wed, 05 May 2004 15:28:23 +0100, Paul Burridge
wrote:



Tell us. Were the readings close to 50, 75 ohms or what?

70-100 ohms depending on the positions of the coarse and fine
attenuator knobs, but not nice and smoothly; jumping around a lot (I
guess noisy pots that just want a squirt of contact lube. Does that
sound right to you? I'd have expected a much greater range...


From an attenuator a large range is undesirable. The opposite
is what you want.
Lets just call the RF output Z for this unit 75 ohms Nominal. :-)
And you have crappy pots to put up with. Not good.

This unit is a bit cheap in the attenuator department.
Pots for both course and fine controls. I don't like that idea.
I prefer a switched attenuator for course and a pot for fine.
I'd much prefer a switch for fine also but that would be
too expensive.

Do a simple leakage test to see if this particular AVO
sig gen is worth keeping. On the bench beside the signal
generator place a radio and see if you can pick up the
signal from the generator. If a signal roars into the radio
then it is next to useless for serious or even hobby radio
work. Shield the RF output connector or short it.
( attenuator set to minimum output)
If it leaks RF and the frequency drifts a lot then you
might as well forget it.

A friend of mine did have a good use for a few old
crappy signal generators. He was into restoring really
old radio sets, record players with big horns and pianolas,
those pianos that play by themselves.
He was giving a demonstration of his gear at his house.
In another room he had the old signal generators being
externally modulated by modern tape recorders playing
old 1920's and 30s type music. The visitors were amused
and confused to hear the old style music coming from
the old style radios as they could tune into the local stations
also. The bull**** flew from those in the know. :-)

Regards,
John Crighton
Sydney