[Test-Equipment] Olders HP Spectrum Analyzers - The YIG?

[wolfbob]

YIG is Yittrium-iron-garnat, a low loss ferrite that is resonate like in a 
tuned circuit at micrwave frequencies determind by a static magnetic field. 
They are used as a preselector as they can be sychronously tuned with the 
BWO. They look a lot like a circulator which is also ferrite device used to 
provide a match to one port no matter what you hang on the other port.

WBob
.----- Original Message ----- 
From: "John Miles" <jmiles at pop.net>
To: "Greg Mijal" <bluebirdtele at earthlink.net>; 
<test-equipment at mailman.qth.net>
Sent: Saturday, January 29, 2005 3:51 PM
Subject: RE: [Test-Equipment] Olders HP Spectrum Analyzers - The YIG?


> Nope; that's a circulator; I forget what its purpose in the instrument is.
>
> The BWO is the large, black, highly-magnetized rectangular prism-shaped
> object with the Watkins-Johnson label.  This is basically a 
> travelling-wave
> tube that's optimized for voltage-controlled oscillator service.
>
> -- john KE5FX
>
> -----Original Message-----
> From: test-equipment-bounces at mailman.qth.net
> [mailto:test-equipment-bounces at mailman.qth.net]On Behalf Of Greg Mijal
> Sent: Saturday, January 29, 2005 3:46 PM
> To: test-equipment at mailman.qth.net
> Subject: [Test-Equipment] Olders HP Spectrum Analyzers - The YIG?
>
>
> Hi:
>
> I recently posted email about the older HP 8551B/851B spectrum analyzers.
> The response was informative and helpful.  The consensus is that this is a
> very robust machine.  I have decided to take a try at getting one of the
> units going after I run a "drying out" process to the units.
> Here's my question.  Someone mentioned that the YIG conversion was good 
> for
> the machine and I think I found what he was talking about.  Would you 
> please
> have a look at the pictures and confirm that that is what he was speaking
> about. It is lower right in the photos. HV tubes removed for safe keeping.
> http://home.earthlink.net/~bluebirdtele/yy.jpg
> http://home.earthlink.net/~bluebirdtele/yx.jpg
> Your thoughts are appreciated. Or should I say I am hanging on every word?
>
> Greg
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