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Bret Ludwig wrote:
wrote:

snip
My experience with several dozen HP 200's does not match yours.
Yes, they all oscillate, but amplitude stability and phase noise is
tube dependent.

i have probably just been lucky.

I would take it , then, that you have not seen more than maybe a
couple of these units, yes? So, you hardly speak from a position
of authority. Having run an electronics calibration lab, and seen
quite a few, I might huimbly suggest my experience trumps yours.

Also I pay little attention to the
dial markings, I use my freq counter to set frequency.

Fine, but that doesn't deal with drift, amplitude instability, and all
the rest.

And I don't use
them for scope cal, there are precision level gens that are used for
that.

And how many of them are solid state

The tube-bigot lie here is that most ICs in good audio test equipment are
standard parts, or can be readily replaced with standard parts.

IIRC the 8903 has a proprietary diff amp that is close to unobtanium.

If you recall, the 8903 is a fairly rare beast in and of itself

Oh no! They were sold by the truckload because they replaced the 339.
Then they went to *ucker in trade for....used 339s....because they
weren't.

You obviously missed my point, or chose to completely dance
around it with irrelevancies. The 8903 is merely ONE example
of audio test equipment. It is not representative of the realm of
equipment as you might suggest it does. Besides, you have
already demonstrated pretty narrow experience with HP200's,
and you did qualify your claims on the 8903 with "IIR," yes?
SO you have yet to provide any substantiation to your claim.

Potomac IIRC essentially cloned the 339, but in two boxes, a
gen and receive, and charged more for either than HP had for the 339.

How in any way, shape or form is this at all relevant?

So 8903s are common as sin. However, barring abuse, they run forever.

Which seems to contradict you earlier point.

I have an entire wall
of audio test equipment from HP, ST, Techron, GR, B&K, Leader,
and so on, and there's nary a proprietary IC in any one of them.

A point you failed to address.

Now the exception is my old, trusty GR 1390B random noise
generator which uses a proprietary noise diode. if it goes, the
unit is worthless. WAIT! It's a vacuum tube, not an IC! Fancy that,
a proprietary, non-replaceable vacuum tube.

A point you failed to address.

I should also add that of all the equipment I have, the tube0based
stuff has been the most difficult to support, because it's becoming
increasingly difficult to find suitable tubes, any ol' fire bottle just
won't do. But , even though the tubes ARE easy to extract, they
WILL have to be replaced at some point, absolute guarantee.

Whether or not any of the solid state units have proprietary parts
that will be hard to replace, I don't know: not a single one of them
has failed.

HP solid state RF gens use a lot of proprietary silicon-8640s

Lessee, HP 8640: signal generator with a range of 500 kHz to
500 MHz. Please explain how that is "audio test equipment."

Well, then I guess an FM tuner isn't an "audio unit".

Last time I checked, the part that an HP 8640 would test isn't.

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