[Lowfer] What is a Selective Level Meter for...

Tue Aug 26 09:25:32 EDT 2008

Tom,
     Thank you for the rundown on the 3586C.  I'm somewhat interested in the 3746A as there are quite a few available on eBay and it interfaces directly with the 3330A/B.  I have a pair of those for IMD testing together with the companion tracking spectrum analyzer and phase/gain meter.

     I wouldn't mind having a 3336 as it is the missing component for my 8407B network analyzer.  It's an antique, but I learned on a full-blown 8407A almost 30 years ago and I know my way around the inards as a result.

     But, if anyone knows if the 3746A has a tracking generator output I would certainly like to know as it would be a cost-effective addition to my test equipment.


>Date: Mon, 25 Aug 2008 21:02:33 -0700
>From: "Chris Trask"
>    I noticed that there are a few selective level meters available on eBay, a pair of 3586's and a 3746A.  Does the 3746A provide a tracking signal?  I saw in the eBay photos that there's a BNC connector on the rear labeled"tracking generator".  Never understood what these level meters were used for,
>----------------------------------------------------------------------- 
>
>One of the most useful devices you will ever have...  In a previous life with a Telecommunications Company the HP-3586 level meter and HP-3336 level generator were the center of my life. I installed and maintained Frequency Division Multiplexers in the 70's and 80's.  FDM Mux is nothing more than a 2700 channel sideband radio with a broadband output from about 100khz to 27mhz. This signal was fed to the input of a microwave transmitter for transmission of analog voice and data signals for long distance transmission.  The 3586 can measure signals from +7dbm to -117 dbm from audio to 30mhz. It has switchable receiver bandwidths of 3khz, 400hz and 20hz.  Likewise, the 3336 level generator can generate signals from audio to 20mhz in increments as small as  .01hz with a sinewave output up to 21mhz and there is a squarewave output on the back that I believe goes up to 60mhz.  Both these pieces of equipment have inputs for an external 10mhz reference such as a
> GPS disciplined Oscillator or a Symmetricom LPRO-101 Rubidium oscillator.  (Those are items available off eBay - currently there are LPRO's from China for about $100 and A Trimble Thunderbolt GPS Disciplined Oscillator is a bit more than twice as much)
>
> Among other things, the 3586 is "intended" to be used for measuring carrier levels, pilot signals and transmission levels on the baseband. The 3336 level generator was used to insert test signals for transmission testing.   As a Ham - I spent a lot of off duty hours using the 3586 as a radio receiver connected to a longwire antenna strung to the top of a 300' tall microwave tower, testing home brew crystal filters, measuring harmonic outputs etc...
>
>In any event, I bought a pair off eBay about a year ago and absolutely love them. I think the set cost me $300 including shipping.  I hook my antenna to the input of the 3586 and the headphone output to my sound card of my laptop. I fire up Spectran and am ready for QRSS.  This stuff is so good that you can tune the high end of the AM radio band and on a quiet winter night see (and measure) 10 to 20 different AM radio station carriers on the "same" frequency.  The FCC gives broadcasters +/- 40hz tolerance for their carriers and believe me, many small rural AM stations seem to be lucky to hold carrier withing that range...
>
>Another great sport is precision frequency measurement testing off the air. Connie Marshall, k5cm runs weekly FMT's for a group of about 20 to 30 hams.  His website is http://www.k5cm.com/  go look at it.  Folks there can measure a 30m signal - skywave with doppler and everything - to better than .01hz   On the ARRL FMT's you get a gold star for being within 1hz and honerable mention for being under 10hz...
>
>Any way, the list of uses is limited only by your imagination.  If you have the bucks a 3586 is a worthwhile investment.  However, buyer beware - there are plenty of lemmons out there.  Try to get one that is stated to power on, and has a photo of the 10mhz frequency display and the level display showing its noise floor reading somewere below -110dbm.  Some time ago there were a bunch of them out there with bad (noisy) receivers and somee hams got hosed in the deal... So research, research, research.
>
>
>      
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Chris

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