[Hammarlund] Additional SP-600 Tuner Funzies

[Al Parker]

Hi guys,
    Well, I'm not positive I'm following this thread properly, but I'll
give it a shot.
    Speaking from a lousy memory and not universal experience, there're no
individual band adjustments for linearity.  (BTW, it's not a PTO, it's a
VFO.)  The dial is "reverse engraved," etched, or some such - the markings
are raised (maybe not universally).  So, unless somebody re-did Dave's,
he's got the original lines, marking, etc.  The endpoints can be set for
each band.  It's been said that there was a woman at the Hammarlund
factory who did tweak the individual split leafs of the tuning variable,
using a jig of some sort, to adjust the linearity, and did something like
5/day.  (Is that what you have done, Dave?)  It has been my experience,
after working on close to a dozen SP-600's in the last several yrs, that
the dial readout is usually within about one pointer width at most, not
all, points thru any band, after setting the endpoints.  That's pretty
darn close for something that's approaching 50yrs old and has probably
been somewhat mistreated somewhere along the way.  I've made charts of
several receivers showing that for several owners, I think at least 1 can
be found on my website (somewhere).  I usually don't set the endpoints as
close to the end of the dial as the manual recommends, so it's "spot on" a
bit inside of the recommended freq.s, and moves a bit off toward the edges
or center of the range.
    None of the receivers of that vintage was meant to be a frequency
standard.  I suppose maybe the Collins's came close with their PTO's, but
they still had to be set at 100kc points to be sure, and you must remember
that they covered a relatively narrow range compared to the SP-600's VFO.
And I've had several Collins's with PTO's that would read 15kc or so off
on the whole span, and couldn't be adjusted enough to come in right.
  - FWIW -
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info


----- Original Message ----- 
From: "Todd Bigelow - PS" <tbigelow@pop.state.vt.us>
To: "Dave Faria" <Dave_Faria@hotmail.com>
Cc: "hammarlund" <hammarlund@mailman.qth.net>
Sent: Thursday, August 21, 2003 10:41 AM
Subject: Re: [Hammarlund] Additional SP-600 Tuner Funzies


> Dave Faria wrote:
>
> >I was curious if the original tuning dial markings could be slightly
off
> >from printing or painting however it was done back then.  I can set the
> >tuning real close for the two upper bands but, then the lower frequency
> >bands linearity is out. If I set the linearity for the lower four
> >bands(using one of the lower bands) then the opposite occurs.  My dial
is
> >original and not a label.
> >
>
> It's the PTO endpoints!! That's it, I tell ya!! Oh, wait a minute......
(o:
>
> Following this closely Dave, just as curious to see the responses as
> you, for my SP-600 alignment/calibration
> adventure to come. Hopefully there are some magical trimmer caps hidden
> somewhere. Doesn't make sense
> that there'd be no way to account and correct for this, you can bet they
> didn't leave the factory like that.
>
> de Todd/'Boomer'  KA1KAQ
>