[Hammarlund] Unstable Oscillator adjustments in the HQ-180

[manualman at juno.com]

If I was to start someplace, I would look at all the common components
associated with T23 through T27. since it's happening on all band
positions, I could eliminate specific capacitors associated with each can
(hard to believe they would be all bad) and as Al pointed out, there are
no caps in these specific cans. I would look, test/measure, and/or
replace the various caps and resistors associated with the 6C4. Caps C60,
C78, C81, resistor R51, and check the two inductors in the plate and
cathode. I would also try another 6C4. 

Learned this from working on Japanese radios: With the transformer slug
removed, take a piece of waxed string and insert into the transformer
coil form. Then, while holding the end of the string, screw the slug into
the coil form. The combo of string and wax will keep the slug from
loosely moving  especially when inserting or removing the adjustment
tool.

Pete, wa2cwa

On Mon, 1 Feb 2016 17:01:56 -0500 "Al Parker" <anchor at ec.rr.com> writes:
> Hi guys,
>     According to my schematic the osc. coils in the HQ-180 have 
> external 
> caps, the IF's have internal, and I've had problems with them a few 
> times.
>     It does sound like that sort of problem, a mechanical one, but 
> it 
> appears that it happens on all bands.  Maybe ck for bad solder 
> connections 
> at the coils or bandswitch?
> 73,
> Al, W8UT
> 
> ----- Original Message ----- 
> From: <w5jo at brightok.net>
> To: "K3PID" <Ron.K3PID at sbcglobal.net>; <hammarlund at mailman.qth.net>; 
> 
> <manualman at juno.com>
> Sent: Monday, February 01, 2016 4:56 PM
> Subject: Re: [Hammarlund] Unstable Oscillator adjustments in the 
> HQ-180
> 
> 
> > What is the condition of the bandswitch contacts.  Had a similar 
> problem 
> > with a National and cleaning them with denatured alcohol  fixed my 
> 
> > problem. Other than that, I am beginning to think the mica 
> capacitors 
> > located in the bottom of the cans are the problem which will 
> require 
> > removal and replacement.  Usually the capacitor problem will be 
> one or two 
> > of the cans not all of them, so what, beside the bandswitch, is 
> common to 
> > the oscillator section.  I believe someone mentioned the 
> oscillator tube.
> >
> > 73,
> >
> > Jim
> > W5JO
> >
> > -----Original Message----- 
> >
> > OK, as far as I can determine the slugs and caps are in good 
> shape. The
> > touchy issue means that when I put the adjusting tool on the screw 
> and 
> > just
> > tweek it a little the output jumps.  On all of the IF 
> transformers, I can
> > turn the adjustment slowly and see the output drop or increase 
> relatively
> > slowly so that I can sweep through the peak and back up to find it 
> then
> > remove the tool and have it stay put.  with the oscillator 
> transformers 
> > even
> > a slight turn causes a sharp change in output and it is almost 
> impossible 
> > to
> > stop on a peak. Sometimes just removing the tool shifts the output 
> peak...
> > The "problem" exist on all of the HF Osc transformers so it is 
> something
> > common to all band switch positions. All the tube socket voltages 
> and
> > resistances are nominal ( ±10% maybe ). I have the set working 
> fairly well
> > but can't help but think that it could be better...  I've been 
> using it 
> > for
> > the Classic Exchange so after Tuesday I will put it back on the 
> bench and
> > continue trouble shooting.... I was hoping someone had experienced 
> the
> > symptom before and could report their findings...
> >
> > TNX  es 73
> > Ron K3PID