[Test-Equipment] Q meter?

[Richard Knoppow]

     The thermocouple in the 260-A is pretty well protected. 
It is the 160A that is prone to burn out. Usually a properly 
aligned 260-A will agree quite closely to the standard 
coils. Its important that the oscillator be accurate but its 
easy enough to check it against a counter.  The standard 
capacitor can be calibrated using a standard impedance 
bridge rather than the rather complex method described in 
the handbook.  The Q meter is very useful for measuring 
small capacitors, down to about 1 uf by substitution.  Its 
also useful for checking the Q of transmitter and receiger 
coils.  While the newer instruments may be faster to use the 
Q-meter will still deliver very useful measurement.  Not 
many people understand what they are.  The handbook has a 
good primer on their use.
    In order to do a proper calibration its necessary to 
have at least two or three standard coils. Each is calbrated 
at three frequencies.  The other coils are "working" coils, 
they are necessary for many measurements. The Boonton coils 
are very high Q, actually higher than the standard coils, 
and are pretty stable. You can make your own but the real 
thing is usually better.  I've found the calibration is 
pretty stable.
     When I was at -hp- we had two guys in our Los Angeles 
shop who worked on all the Boonton stuff. Q-meters and 
especially the 250-A RX meter are not easy to get to specs 
but are generally stable once you get there.
     With a little care a 260-A will last a lifetime.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com


----- Original Message ----- 
From: "Carl" <km1h at jeremy.mv.com>
To: "Discussion of Electronic Test Equipment" 
<test-equipment at mailman.qth.net>
Sent: Wednesday, June 18, 2014 5:34 PM
Subject: Re: [Test-Equipment] Q meter?


> Brian, Id suggest staying away from the Boontons as they 
> are all based upon 30's technology, touchy to use, easy to 
> damage the thermocouple, and finding a NOS special 
> selected version of a 2A6 for the 260A will cost more than 
> the whole meter. The Boonton tube is a BRC 535A.
>
> And to add insult to injury the readings will only agree 
> .....maybe....with another of the family and not the 
> current industry standard HP 4342A. If all you are 
> interested in is relative readings then the 260A will at 
> least let you make comparisons. A Heathkit QM-1 is a 
> better choice if all you want is relative readings. It is 
> somewhat based on a Boonton 190A with less hassles and kit 
> accuracy.
>
> I used a 260A for many years at National Radio and bought 
> it years later at auction with a set of "standard" coils. 
> It was in need of an overhaul and recal and required a bit 
> of work to get the oscillators to agree with the dials.
>
> I sold it in 1999 (kept the standard coils) after picking 
> up a HP 4342A at a local belly up auction for $200.
>
> The military had the TS-617/U, plus an A, B, and C 
> version. All but the C used the Boonton circuit. The C is 
> a completely different design from a 1975 USAF contract 
> and has none of the Boonton idiosyncracies. I picked one 
> off of Fleabay for $75 in 2006 and it worked well within 
> spec without any work. It is tube based but no paper caps, 
> uses A-B resistors and mil-spec electrolytics. All tubes 
> tested as new.
> I use this one primarily for coils used in tube gear such 
> as rewinding a front end receiver coil or input/output 
> coils in transmitters and amps. The HP is used at VHF and 
> with Litz wire at IF frequencies.
>
> Here is some good reading
> http://www.qsl.net/k5bcq/qmeter/qmeter.html
>
> Carl
> KM1H
>
>
>
> ----- Original Message ----- 
> From: "Brian Burns" <brian at lessonsinlutherie.com>
> To: "'Discussion of Electronic Test Equipment'" 
> <test-equipment at mailman.qth.net>
> Sent: Wednesday, June 18, 2014 5:39 PM
> Subject: [Test-Equipment] Q meter?
>
>
>> Hello All,
>>
>>
>>
>> There has been quite a bit of chat about Boonton Q 
>> meters, in a peripheral
>> sort of way, over on the funwithtubes group. It's made me 
>> curious about the
>> usefulness of that device, or some other brand, on an RF 
>> experimenters test
>> bench. Opinions?
>>
>>
>>
>> Cheers,
>>
>>
>>
>> Brian
>>