SINGER SPA-100 SPECTRUM ALALYSER MANUAL PLEASE

[alanainslie]

I have a nice Singer SPA-100  Spectrum Analyser - the EHT has decided to die and I have no manuals.
Can anyone assist plesase? 
Tried the usual sources (I think).

Thanks
Alan A

[coppercone2]

That looks like a nice unit that you might be able to trouble shoot even without knowing anything. Did you do a check for obviously burnt/damaged components, broken wires, etc?

[coppercone2]

https://www.ebay.com/itm/125141420223

this might be a start for 15$. I see block diagrams at least.

[coppercone2]

https://emperoroftestequipment.weebly.com/

Picture
Singer SPA-100:  "40 GHz Spectrum Analyzer."  I put the description in quotes because it really isn't a spectrum analyzer and really doesn't do 40 GHz as shown.  And to make matters worse, it sometimes goes by Singer, Panoramic, or a variety of sub-companies of Singer Instrumentation.  As the picture shows, the SPA-100 consists of an MF-100 mainframe and an RF-100 tuning head.  Presumably, other tuning heads were available 50 years ago when this beast was manufactured.  It will do 11 GHz as pictured; to get higher than that, one needs an external mixer.  This threw me for quite a loop when I wasted an afternoon trying to debug why I couldn't see anything when I hooked up a 12 GHz signal to the 11-40 GHz input!  Now, follow me on this:  A modern spectrum analyzer tunes the 1st LO (usually a YIG) very quickly and thus can put up a full-band span.  The SPA-100 uses a microwave triode tube and a mechanically tuned cavity as the 1st LO.  So it will only tune as fast as you can turn the front panel tuning knob.  The way they get a sweep on the CRT is by sweeping the 2nd LO, not the 1st LO.  And that restricts you to a maximum span of 100 MHz centered about where you manually set the center frequency.  So it really acts like a receiver with a panadapter on the IF, i.e., a "panoramic receiver."  I won't bore you with the specs; they are pretty atrocious by today's standards.  And forget trying to do any kind of absolute measurements.  The chief utility of this piece is to verify the proper relative spectra of various modulated microwave signals, that's about it.  The pictures shows the spectrum of a 7.2 GHz pulse modulated signal out of my Gigatronics 900.  Probably a miracle back in the 1960's, but a real boat-anchor today.  Grade: B-  (OM)

Advertised as working, I fully expected the seller to be joking, but he wasn't - it did work.  It did need some tuner cleaner and the HV wire to the CRT was loose.  Other than that, the only thing that didn't work right was the 1 MHz RBW filter.  But when I took that circuit out of the unit and tested it on the bench, I couldn't find anything wrong with it.  So back it went and it now works fine in the unit.  Probably just a bad connection somewhere that I inadvertently corrected.​  All the 50 year old Sprague electrolytics tested fine, but I'll probably re-cap the unit anyway.  I don't expect too much further longevity of this unit and once in a while it needs a good whack on the cover to settle down!

SO that means what you might be looking for is a MF100 mainframe manual, presumable the scope EHT is part of the main frame. Also check for loose sockets for tubes, it could just be a damn socket, it sounds like that is powered by tubes. Can't hurt to just clean it through if you can't find a manual (look up tube socket cleaning guides).

[wn1fju]

I've attached two schematics from my MF-100 mainframe manual concerning the CRT.  One is for the HV power supply and the other is a general interconnect diagram.  Hopefully that will get you started.

I have the hardcopy manuals for the spectrum analyzer, but it is >100 pages and has a lot of fold-outs.  The only thing I'm able to do is a quick photo of a page or two at a time. 

In a perfect world, I would lend you the manual.  But the last time I tried that, the recipient was in Canada (I am in USA) and it got held up at a UPS store right near the border.  Then Covid hit and border crossings were suspended.  The poor guy never was able to get the UPS delivery and after well over a year, I contacted UPS and had them ship it back (at my expense).  I've learned my lesson, no more manual lending!