[Test-Equipment] Millen GDO question

[Richard Knoppow]

----- Original Message ----- 
From: "Ron Youvan" <ka4inm at tampabay.rr.com>
To: "Richard Knoppow" <1oldlens1 at ix.netcom.com>; "Discussion 
of Electronic Test Equipment" 
<test-equipment at mailman.qth.net>
Sent: Wednesday, August 03, 2011 4:18 PM
Subject: Re: [Test-Equipment] Millen GDO question


> Richard Knoppow wrote:
>
>>       Some of you know that I obtained the VHF "coil"
>>   actually a hair pin through the kindness of a fellow on
>> this list. My question is for others with the same meter.
>> How much current is normal for hairpin to indicate? Mine 
>> is
>> quite low and I think it quits oscillating below about
>> 140mhz. That is the low frequency limit as given in the
>> handbook so it might be normal. The hairpin appears to be
>> perfect and the tube tests good, actually rather hot, on 
>> two
>> different testers. So, I suspect this is normal but want 
>> to
>> confirm that. The current indicated on the meter varies 
>> with
>> different coils but is significantly higher on the next
>> lowest one. Its curious that the output is lower at the 
>> low
>> end of the band but that's true of all the coils.
>
>   If we are discussing the meter reading, it is a function 
> of the oscillator tube's grid current.
> Try another tube and see if it continues to oscillate 
> throughout the frequency range of it's UHF band.
> -- 
>                           sent with LINUX
>    Ron  KA4INM - Linux, the way to get rid of viruses!
>                 -- MaDsen Wikholm, mwikholm at at8.abo.fi

    What I wanted to know was if this was normal behavior. I 
will have to obtain a couple of fresh tubes and try them. 
Even though the current tube tests good on a TV-7 it doesn't 
mean it is good enough for this circuit. The meter reads 
quite high on the other bands although it varies quite a bit 
from one to another and across each. That I would consider 
normal. I think the hair-pin coil is just fine, in fact 
there is not much that could go wrong with it. The 
frequencies are reasonably correct on all of the coils. I 
think there was probably some sort of adjustment for this at 
the factory but I am not about to fuss with it to try to 
make it better than it probably was new.


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