"tuning plates", HR-10's et al...

[Bill Coleman AA4LR]

On 3/15/98 20:40, Guy G. Giacopuzzi DDS at ggg3dds at JS-NET.COM wrote:

> When
>I worked at Heath, I remember using what I thought was a "factory
>issued" "tuning plate" (bottom cover) for the HR-10's during tune up.
>Once tuned, we'd take off our plate, and  replace it with the
>customer's.  Thus, it would appear, that unless an enterprising ham
>drilled his own bottom plate, it was close to impossible to tune an
>HR-10!  If you tuned it without a "tuning plate" (bottom off), and then
>put the standard bottom plate back on, it would throw all your
>calibrations of the occillator coils and rf coils off!

As a pre-Novice, I bought and built one of the last HR-10B's off the line
in March of 1975. My solution to the tuning problem was simple. I
borrowed a "nibbler" and cut a slot down the bottom plate where the coils
were. This made tuneup a breeze.

The HR-10B sure had a great lack of selectivity for the bands of the
middle-70's. Plus, the 10m band was practically deaf. It worked OK on
80-15, though.

I tried changing the crystal filter by swapping one of the crystals with
my brother's HR-10B (ie so I'd have two identical crystals), and
re-tuning the IF. Didn't work. Instead, the IF apparently got tremendous
feedback.

Oh, and I made the modifications that were in the November 1972 "73"
Magazine. Really helped with the AGC and the stability of the rig.

Sold that rig in 1980 or so at a Hamfest for about $20. Ouch.




Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at radio.org
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901

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