GR-64 Info wanted

[Bill Coleman]

On 10/27/00 11:36 AM, Deane D McIntyre at dmcintyr at ucalgary.ca wrote:

>I have a copy of the schematic from the web but was wondering
>if someone could provide alignment instructions for this
>rather simple receiver. I notice that there are no trimmer caps
>for Band D - does one use the trimmers on the main tuning cap
>for this purpose, then go ahead and do bands A, B, and C?

It's been a long time since I had a GR-64, but that's how I remember it.

You use the trimmer caps to help correct the tuning dial. The idea is to
use a reference frequency near the bottom of the band, and tune that in
with the coil slug. Then pick a reference near the top of the band and
tune that with the trimmer cap. Go back and forth until the dial is
correct (or as close as you can get it)

>If this is the case, than where is the ant. trimmer cap for
>Band A? Perhaps the correct proceedure is to align Band A
>first, using the trimmers on the main tuning cap, and hope
>that the low end of band D comes out more or less correct
>after aligning the high end with the iron cores in the coils in
>the usual manner.

Band A uses the internal ferrite loop antenna, so it doesn't need a
trimmer. In fact the AM BC stations are usually so loud the trim isn't
necessary.

Band D needs the most help with trim. The GR-64 uses a pentagrid
converter that doesn't oscillate high enough for Band D -- the oscillator
actually generates a second harmonic for the mixer. That's one of the
reasons Band D sensitivity is lower on the GR-64 -- less LO injection
energy.

>Anyhow, any help or advice would be appreciated. I have a
>sig generator and VTVM (both Heath of course) so I want to
>do a proper job of the alignment. Lastly, where should the
>tuning pointer be positioned with the tuning cap fully
>closed (or open)?

When fully closed, the tuning dial should be near the bottom of the bands.

>I also observed that the audio is lacking in bass - is this
>the nature of this beast?

I don't remember it being so. You might check the coupling caps in the
audio stages. I know I lost one of the HV bypass caps in my GR-64 at one
point.

--

Still looking for a GR-81 for parts, or at least a Heath #26-85 4 pf
variable capacitor to help restore GR-81 (needs the cap and the dial
sub-panel).



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

Listserver Subscription:listserv at listserv.tempe.gov - "subscribe heath 'name' 'call'"
Listserver Submissions: heath at listserv.tempe.gov
Listserver Unsubscribe: listserv at listserv.tempe.gov - -"signoff heath"