Amps
[Top] [All Lists]

[AMPS] Use of the Johnson Matchbox

To: <amps@contesting.com>
Subject: [AMPS] Use of the Johnson Matchbox
From: chucky@aloha.net (Mike Sato)
Date: Wed, 31 Mar 1999 10:47:31 -1000
if anyone knows of which issue of QST...please let me know too...

I am looking for some high power tuners...not sure what to get...

Mike KH6TO

----------
From:   Len Schaier[SMTP:lschaier@avotec.com]
Sent:   Wednesday, March 31, 1999 10:30 AM
To:     Rich Measures; 'amps'
Subject:        RE: [AMPS] Use of the Johnson Matchbox


Rich,

I believe the ARRL test was in fact reported in QST. They were lab testing a
number of tuners.

Len



At 02:26 AM 3/31/99 -0800, Rich Measures wrote:
>
>
>
>>
>>Jim says:
>>
>>>  >I am pondering ways of actually measuring the efficiencies of these
>>> tuners,  >but am not sure how to proceed.  
>>> 
>>> 
>>measure the load impedance, measure the current with a thermo ammeter.
>>Calibrate the thermoammeter with DC: measure its RF resistance (not easy!)
>>at the frequency in question, ,measure the DC resistance and calculate a
>>correction factor. Taking into account the inaccuracies, and the fact that
>>the tuner should hopefully be 98% efficient or better, you may well find
>>that the measurements tell you that the tuner is really an amplifier!
>>
>>Seriously, I think the best way to get an idea of tuner efficiency is
>>temperature rise after ten minutes of key down at full power. And if the
>>Delrin catches fire before then, you know it ain't that efficient..........
>>
>Unsubstantiated rumour has it that in the ARRL lab test of the MFJ "3kW" 
>tuner Delrin ignition occurred at c. 30% of the mfg.-rated power level.  
>>
>-  later, Peter
>
>
>Rich...
>
>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  
>
>
>--
>FAQ on WWW:               http://www.contesting.com/ampfaq.html
>Submissions:              amps@contesting.com
>Administrative requests:  amps-REQUEST@contesting.com
>Problems:                 owner-amps@contesting.com
>Search:                   http://www.contesting.com/km9p/search.htm
>
>
>




--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm




--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm


<Prev in Thread] Current Thread [Next in Thread>