[Collins] Re: QRZ ALL R388 EXPERTS




At noon lunch today I thought I would try something.  I did a quick and
dirty adjustment on the BFO and found it to be way off.  After bringing it
into alignment I found that the trouble explained below basically went away.
Now the difference is only 500 cycles or so between bands.  Also, the zero
frequency is now more centered in the dial window.

Haven't studied as to why this is the case, but, I now know that a good
alignment should be all that I need to do to bring this receiver back into
spec.

Tom...W0ZR
----- Original Message -----
From: Tom Lutz <telutz@xxxxxxxxxx>
To: <ian_webb@xxxxxxxxxxx>
Cc: <collins@xxxxxxxxxxxxx>; <collins@xxxxxxx>
Sent: Wednesday, December 13, 2000 10:03 AM
Subject: Re: [Collins] Re: QRZ ALL R388 EXPERTS


> Let me first thank all of you who have responded to my post on the R388.
> All the answers were interesting and gave me food for thought.
>
> I think that Ian has probably hit on what makes the most sense, at least
to
> me, considering the "every other band" phenominan.  I am going to do an
> alignment this weekend and I will let you all know what happens.
>
> Thanks again to everyone's responses.
>
> Tom...W0ZR
> ----- Original Message -----
> From: Ian Webb <ian_webb@xxxxxxxxxxx>
> Cc: <collins@xxxxxxxxxxxxx>; <collins@xxxxxxx>
> Sent: Tuesday, December 12, 2000 9:39 PM
> Subject: [Collins] Re: QRZ ALL R388 EXPERTS
>
>
> >
> > It seems to me that the ORIGINAL QUERY hasn't been carefully considered.
> Though
> > it's been years since I've worked on an R388 or 51J I couldn't continue
to
> sit
> > on the sidelines mute so I dragged out my military manual for the R388.
> >
> > Sure enough, it states under "Variable Intermediate Frequency" that
> >
> >      "The variable intermediate frequency consist of two ranges:
> >      one for a frequency of 2.5 to 1.5 mc, and the other for 3.5 to 2.5
> >      mc, used on even-numbered and odd-numbered bands, respectively.
> >      Using two variable i-f bands in this manner, cuts in half the
number
> >      of crystals necessary in the h-f oscillator..."
> >
> > This should be an obvious clue to think about since the original post
> talks
> > about EVERY OTHER BAND being off.
> >
> > >>  The frequency alignment (the dial
> > > > setting) seems to shift by the same amount as I change to every
> > > > other band position.
> >
> > Hmmm.... wouldn't you think that might have something to do with the
> alternating
> > use of different IF frequencies???  For band segment 4 and up, on one
band
> > segment the signal goes into the FIRST MIXER and in the next it goes
into
> the
> > SECOND MIXER using the different IF frequency on alternate bands.
> >
> > I'd sure want to do a careful alignment using a decent counter to set
the
> > frequencies used BEFORE I go off on a tangent of buying a whole set of
> crystals
> > to replace for fear that they are all bad with age.  (Even without a
> careful
> > alignment it would be possible to "split" the difference so bands were
all
> > within 2.5 kc of the same on the dial if you didn't want to do an
> alignment.)
> >
> > Just my two cents worth!
> >
> > Ian, K6SDE
> >
> >
> >
> > Sponsored by the Collins Collectors Association
> http://www.collinsradio.org
> > Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
> > Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
> >
> >
>


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