[HBR] HR-67

[Diane Swynar]

Hi All...

A VERY interesting thread going on here in the matter of homebrew
receivers, one that I especially enjoy reading!

One little caveat to receiver builders who, like me, wind their own coils
in RF amplifiers, etc., and that is this: do NOT place your link coil too
close to the main tuning coil. I did just that with my version of the Mate
For The Mighty Midget receiver, hoping to maximize sensitivity of the final
product, above all...

The coils are over-coupled: when I'm trying to listen to AM on 1885-KHz
with an SSB or CW contest down the band, I can hear the junk all over the
dial! Now, I agree this receiver isn't the last word in complexity & all,
but I know if I had separated the two coils up to a maximum of 3/8" apart
(as suggested by Rocky in his regen books), the set-up would have had a LOT
more up-front selectivity, where it really counts.

I took a look at the underside of that little rascal the other
day...wouldn't take but two new pill containers & some enamelled wire to
make things right...!

Anyway, this subject is probably hardly ever seriously challenged or
questioned by builders who simply follow article instructions to the letter-
--now I know why! Hi Hi

~73~ Eddy VE3CUI - VE3XZ







>
>>
>> v
>>
>> The HB-67 did not appear in QST. It was first described in the 1967
>> ARRL Handbook, and was designed by W1DX (Byron Goodman). A later
>> version appears in the 1969 Handbook, but by 1971 the receivers are
>> all sandstate.
>
> OK! That explains why I can't find it. Don't have those handbooks.
>>
>> The HB-67 is an 80 meter receiver having a 455 kHz IF, a crystal
>> controlled converter for the 40,20,15, and 10 meter bands, and a solid
>> state power supply all on one chassis. The coverter is switched out of
>> the circuit on 80 meters. Selectivity is fixed at 2.1 kHz by the use
>> of an SSB mechanical filter. Audio-derived AGC is provided, and the 80
>> meter section uses a single-ended 7360 mixer.
>
>>From your description it does't sound like my cup of tea.
>>
>> >  -
>
>>
>> There are other beam-deflection tubes that are more common and cheaper
>> than the 7360. The 6JH8 and 6ME8 are often-overlooked examples.
>>
>> The Pullen mixer design is credited with high performance yet is
>> simple and sure-fire. The recommended mod for the 75A-4 first mixer is
>> a 6ES8 Pullen mixer over the 7360.
>
> That's basically the 6J6 dual triode mixer I mentioned.
>>
>> >  -No RF stage
>>
>> This can cause problems with IF feedthrough, images and spurs, but is
>> a good idea if you can get adequate RF selectivity ahead of the first
>> mixer. I have often thought that a double-tuned input circuit using
>> really BIG Miniductor or other high Q coils might be the answer.
>
> A couple of tuned circuits is the answer.  Many people think they HAVE
> to  have an RF tube in there.  Not so until one hits 15 Mhz or so.  I
> have 3  receivers that don't have an RF stage.  Don't miss it on 40
> mtrs.  Choosing  an IF freq.  is important.  Running only one mixer
> oscillator makes things  alot easier to clean up.
>>
>> >  -Modular construction
>>
>> A good idea but drastically increases construction time.
>
> Time I've got.  I'm really looking to make this receiver more flexible
> for  future mods.  One receiver I have, I built with the front end
> modular.  I  have 5 different modules built in 2.5 x 5.0 inch
> miniboxes.  The "standard"  6xxx RF with a 6BE6 mixer is really the
> worst setup I have.  Cheap and it  somewhat worked, for the
> manufactorers.  The dual triode is about the best  (no RF stage).  The
> 7360 module I have is setup as a real balanced mixer and  is a bear to
> keep balanced.  Using this tube single ended which most  designers do
> seems to be defeating the purpose of using it.
>
> Thanks for the input.  CU on the list.
>
> Regards,
> Helm.  WB2ADT
>>
>
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