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(OT) Recommendations for Testing

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Edward R Cole

(OT) Recommendations for Testing

I will be testing some amplifiers, soon, and would like advice or
links to info on making IMD and harmonic level tests on HF amplifiers.

I can generate two-tone modulation and monitor spectrum up to 196 KHz
width with my SDR-IQ, but do not have a spectrum analyzer. I have a
scope, power meters, 500w coaxial load, XG3, and a couple DMM, plus
analog 30v and 30a dc meters..

73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-?
DUBUS Magazine USA Rep [hidden email]
"Kits made by KL7UW" http://www.kl7uw.com/kits.htm
======================================
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Don Wilhelm-4

Re: (OT) Recommendations for Testing

Ed,

No Spectrum Analyzer? You do have your SDR-IQ that will do that task on
a narrowband segment. For a more detailed analysis take a look at
G4AON's Simple Spectrum Analyzer at http://www.astromag.co.uk/ssa/.
While the mixer should have a +7 dBm LO input, it should be usable with
the XG3 0 dBm output (or build up an MMIC board with 7 dB gain.)

73,
Don W3FPR

On 3/17/2012 3:19 PM, Edward R. Cole wrote:

> I will be testing some amplifiers, soon, and would like advice or
> links to info on making IMD and harmonic level tests on HF amplifiers.
>
> I can generate two-tone modulation and monitor spectrum up to 196 KHz
> width with my SDR-IQ, but do not have a spectrum analyzer. I have a
> scope, power meters, 500w coaxial load, XG3, and a couple DMM, plus
> analog 30v and 30a dc meters..
>
>
> 73, Ed - KL7UW, WD2XSH/45
> ======================================
> BP40IQ 500 KHz - 10-GHz www.kl7uw.com
> EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-?
> DUBUS Magazine USA Rep [hidden email]
> "Kits made by KL7UW" http://www.kl7uw.com/kits.htm
> ======================================
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

______________________________________________________________
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Joe Subich, W4TV-4

Re: (OT) Recommendations for Testing

> For a more detailed analysis take a look at G4AON's Simple Spectrum
> Analyzer at http://www.astromag.co.uk/ssa/. While the mixer should
> have a +7 dBm LO input, it should be usable with the XG3 0 dBm output
> (or build up an MMIC board with 7 dB gain.)

SDR-IQ with SpectraVue or another SDR application will do everything
G4AON's "Simple Spectrum Analyser" will do. The only thing I would
add to the SDR-IQ is a directional Coupler (Elecraft CP-1) with the
appropriate coupling factor.

The resistive tap used by G4AON is also usable (SDR-IQ connects where
he shows the SBL-1) but a directional coupler will give more accurate
measurements in the presence of SWR.

If you're measuring outputs of more than 100W you will need more than
30 dB of coupling factor in the directional coupler or resistive tap.
I would keep the input to the SDR-IQ substantially below 0 dBm. -50
dBm (~S9 + 20 dB) is a good target; you can get there using both
the coupling factor in the CP-1 and fixed attenuation between the
sample port and SDR-IQ.

Finally, if you are measuring amplifiers above 30 MHz you will need
a converter ahead of the SDR-IQ. Make sure your sample level is
within the signal handling range of the converter.

73,

... Joe, W4TV

On 3/17/2012 3:38 PM, Don Wilhelm wrote:

> Ed,
>
> No Spectrum Analyzer? You do have your SDR-IQ that will do that task on
> a narrowband segment. For a more detailed analysis take a look at
> G4AON's Simple Spectrum Analyzer at http://www.astromag.co.uk/ssa/.
> While the mixer should have a +7 dBm LO input, it should be usable with
> the XG3 0 dBm output (or build up an MMIC board with 7 dB gain.)
>
> 73,
> Don W3FPR
>
> On 3/17/2012 3:19 PM, Edward R. Cole wrote:
>> I will be testing some amplifiers, soon, and would like advice or
>> links to info on making IMD and harmonic level tests on HF amplifiers.
>>
>> I can generate two-tone modulation and monitor spectrum up to 196 KHz
>> width with my SDR-IQ, but do not have a spectrum analyzer. I have a
>> scope, power meters, 500w coaxial load, XG3, and a couple DMM, plus
>> analog 30v and 30a dc meters..
>>
>>
>> 73, Ed - KL7UW, WD2XSH/45
>> ======================================
>> BP40IQ 500 KHz - 10-GHz www.kl7uw.com
>> EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-?
>> DUBUS Magazine USA Rep [hidden email]
>> "Kits made by KL7UW" http://www.kl7uw.com/kits.htm
>> ======================================
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Geoffrey Mackenzie-Kennedy-3

Re: (OT) Recommendations for Testing

In reply to this post by Edward R Cole

Ed,

A very important consideration when measuring the IMD performance of an
amplifier (or certainly a receiver), is that the level of any
intermodulation products generated by the test equipment must be low enough
so that they do not introduce measurement error. Among the usual sources
of these rogue IMD products are the spectrum analyzer (for sure if is
overdriven), the combiner used to combine the two test tones, and the
harmonics generated by the two test tone sources - all of which can be
muzzled.

Of course the better the IMD performance of the DUT, the more significant is
the the error introduced by any test equipment generated products.

If you will bear with me (it is late here), and if of any interest to you, I
can send you off list later today more detailed information.

73,

Geoff
LX2AO

On March 17, 2012 at 20:19 +0100, Edward R. Cole wrote:

Geoffrey Mackenzie-Kennedy-3

Re: (OT) Recommendations for Testing

In reply to this post by Edward R Cole

Ed KL7UW,

After sending you a message at 01:06 Luxembourg time this morning, with copy
to the List, I received the following:

Quote

"The following message to <[hidden email]> was undeliverable.
The reason for the problem:
5.1.0 - Unknown address error 571-"5.0.0 Dynamic zone 195.46.255 not
allowed; relay through your provider's servers"

Unquote.

This has happened before when I tried to send an email to somebody else in
Alaska from LX.

If you still need any advice or links to info about IMD testing, please let
me know - perhaps some kind soul would relay your message.

My aplogy to all for using the List to send this message.

73,

Geoff
LX2AO

----- Original Message -----
From: "Edward R. Cole" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, March 17, 2012 8:19 PM
Subject: [Elecraft] (OT) Recommendations for Testing

>I will be testing some amplifiers, soon, and would like advice or
> links to info on making IMD and harmonic level tests on HF amplifiers.

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html