[Amps] Checking for IMD

[Will Matney]

All,

One can buy a spectrum analyzer with tracking generator that goes to about 1.2 GHz for around $800 to $900 new. These are the same as the Hameg, and a few companies are getting them private labeled for them. I think the same company is who's making them for B&K. They show up on ebay all the time from reputable sellers. I've actully got my eye set one one of them to replace my old one. One of the old HP analyzers with a tracking generator goes for about this amount if it's in decent shape.

Best,

Will

*********** REPLY SEPARATOR  ***********

On 8/11/06 at 11:36 AM m.ford wrote:

>Is anyone using the SDR-14 for IMD measurements? I bought one last
>year for just that purpose but ended up using it as a receiver instead.
>I want to buy another one to use for bench work. Unfortunately I just got
>taken by an SA dealer on ebay for 1500 so I wont look there again.
>
>The SDR-14 certainly looks promising for a FFT based IMD analyzer.
>
>Mike  k1ern
>
>
>----- Original Message ----- 
>From: "Martin AA6E" <aa6e at ewing.homedns.org>
>To: <amps at contesting.com>
>Sent: Friday, August 11, 2006 10:43 AM
>Subject: Re: [Amps] Checking for IMD
>
>
>> Bill,
>> 
>> I've wondered about this, too.  The lab method is to use a high-priced 
>> spectrum analyzer, but couldn't you do something useful with a soundcard 
>> based spectrum analyzer?  You would need to have a linear detector and a 
>> two-tone audio source.  This would be similar to the IMD measurement you 
>> get with a PSK31 monitor.  The trouble is you need pretty good dynamic 
>> range to measure a healthy system.
>> 
>> You could check the boxes being sold by www.cleanrf.com as described in 
>> the latest CQ.  They let you look at "linearity" on a scope.  My take is 
>> that you will only catch gross non-linearity (overdrive), but you 
>> wouldn't get quantitative IMD numbers with this approach.
>> 
>> 73 Martin AA6E
>> 
>> Bill Turner wrote:
>>> Is there a simple procedure one can use for checking the IMD of an
>>> amplifier? Frankly, it's something I have never tested myself, instead
>>> just keeping the amp tuned correctly and underdriving when using SSB.
>>> I've never gotten any complaints of splatter so I think it's under
>>> control. Since I do mostly RTTY and some CW it has not been an issue
>>> but I would like to be able to check it. 
>>>
>>> Any recommended reading on the issue?
>>>
>>> Bill, W6WRT
>>> _______________________________________________
>
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