[Test-Equipment] HP-606A Calibration question

[Carl]

Barry, in that case you have no choice but to reset the dial. As long as it 
is apart look for the orignal set screw marks.

On the BCB range that you indicated earlier the linearity can be well under 
spec. If necessary very carefully move plates for the worse case band.

On the ham bands or general coverage receivers the 606A built in calibrator 
works great. The first time I used a 606A was at National Radio when the 
GR-1000A's were replaced.

I use a 606A and 8640B here, the 606 has better phase noise performance and 
its a lot more convenient for general coverage receiver alignment.

Most 606 problems are 12B4's with leakage, other weak tubes and a small 
electrolytic or so, usually in the modulator.

Carl



----- Original Message ----- 
From: "Barry" <n4buq at knology.net>
To: "Discussion of Electronic Test Equipment" 
<test-equipment at mailman.qth.net>
Sent: Tuesday, May 26, 2009 4:20 PM
Subject: Re: [Test-Equipment] HP-606A Calibration question


>> Q Dope is still sold by General Electronics (GC)
>>
>> As far as the 606A make sure that none of the plates have been bent. If 
>> so
>> straighten them out. Ive yet to see the dial loosen up and use that as an
>> absolute last resort. Ive overhauled many 606's over the decades and its
>> rather easy to get the alignment within the dial line width by following
>> the manual.
>>
>> Carl
>> KM1H
>
> Hi Carl,
>
> All I've seen in the manual is to adjust the L at the low end and the C at 
> the top end of each range.  I don't recall seeing
> anything about linearity or other preparations for calibrations that 
> effect linearity.  Is there something else to this that
> I've missed?
>
> As I said, the variable capacitor on this one is pristine so, no, I 
> wouldn't attempt to bend the fins.  Even as a last resort,
> I'm sure all I'd do is make things worse if I tried that.  The dial plate 
> was lose when I got (it was way off from where it
> should have been by 15 degrees or more) it so I really don't know where it 
> was originally.  I've disassembled and reassembled
> most of the dial mechanism to clean it and get everything working smoothly 
> again.  If small rotational differences can make a
> difference in calibration/linearity, then this may very well be the 
> problem here.  If not, I'm not sure what else to do.
>
> BTW, when you say "within the dial line width", do you mean over the 
> entire range?  I think the spec is 1% which I assume is a
> bit wider than that.  Wow.  If these will stay within line-width accuracy, 
> then I'll be a very happy camper.
>
> Thanks,
> Barry - N4BUQ
>
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