[Test-Equipment] HP-606A Calibration question

[Richard Knoppow]

----- 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 12:20 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
>
    My experience has been different than Carls. While the 
dials don't loosen up they are sometimes mis-set by careless 
repair people.
    The frequency calibration should come in to no worse 
than half the spec, it is very good all over. The error is 
determined by the characteristics of the tuning caps, they 
are pretty accurate although I have some vague memory that 
there were some bad ones. I have no idea of how the stators 
on my generator got tilted, it would have taken a lot of 
force, enough to damage a lot of other stuff and there was 
no sign of that. Whoever bent the plates evidently didn't 
realize that the stators were off or didn't know how to fix 
that.
   You should be able to get the calibration right on the 
nose on one of the low bands and have it correct on all 
bands once the L and C are done. Again, once the shield 
cover is replaced the high end will need to be touched up. 
Evidently the amount of disturbance to the amplifer is 
little enough so it doesn't need touching up.
    The dial slipping procedure is not in the manual, I 
learned it at -hp-, it works. BTW, if you ever run across a 
608C/D they can also be brought exactly on the money. Both 
generators were designed by Art Fong who was one of the 
great designers at -hp- in the old days.
    You are unblocked from my e-mail..

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