[HBR] HB-65, anyone, anyone?

[shoppa_hbr at trailing-edge.com]

N2EY at aol.com wrote:
> I don't think it tunes 10 meters as designed, though. Check the het xtals - 
> it doesn't have one for below 28 Mc.

At least in the '66 handbook, it has a bunch of crystals in the 10M/11M
range.

> The design of the HB-65 was obviously influenced by the "Miser's Dream" which 
> was in QST about the same time, and by the W6TC HBRs. 

> > Looks to me a lot like DeMaw's solid state receivers of the 70's.
>
> How? 
>
> The HB-65 uses only LC filtering - no xtal or mechanical filters. Multiple 
> conversions, too. 

I was thinking of the crystal controlled-converter in front of the
"tunable IF" (aka 80 and 40 meters.)

> > Very well-balanced radio, not too much gain, no whiz-bang features,
> > well thought-out bandswitching that doesn't try to give the kitchen
> > sink but instead gives exactly what is needed in a ham receiver.
> > 
>
> Sort of.
>
> For all that complexity, there's no sharp filter for CW. The AGC is audio 
> derived and the selectivity is so far from the antenna on 20 through 10 that the 
> dynamic range is probably compromised. Some unusual tubes, too. Uses a lot of 
> IF transformers that are difficult to get today (two 1700 kc, four 100 kc, 
> plus 100 kc. BFO). Even though it has AGC there's no S meter.

Again, I call most of the missing features bells and whistles :-). The
bunch of IF transformers is common to all the double-conversion non-crystal-
filter receivers.

> The ARRL Handbook projects come from three sources:
>
> 1) Projects that were originally QST articles written by the ARRL Hq staff. 
> 2) Projects that were originally QST articles written by hams not on the ARRL 
> Hq staff.  
> 3) Projects that were developed by the ARRL Hq staff specifically for the 
> Handbook.
>
> How much of each type appeared in the Handbook varied over time. My 
> impression of the '65 and '67 Handbooks (I don't have a '66) is that most of the 
> projects in them are from the 3) category, above. The HB-65 is definitely 3).
>
>
> >Was it (by my guess) Doug DeMaw?
>
> It's almost certainly a W1DX (By Goodman) design and construction project. 

Hmm, could be. Although DeMaw's trademark to me was always simplicity
in bandswitching and purposeful exclusion of the kitchen sink features,
if you look at his earliest articles he had not quite perfected the
formula, so I was allowing a little leeway :-). Certainly the Goodman
and Hayward designs tend in that direction too.
 
I remember a lot of late 60's/early 70's construction articles
that specifically identify the Kurz-Kasch knobs used. Were those
DeMaw's or somebody elses? Somebody really liked those knobs, and
somebody really liked those 7360's!

> The HB-65 has some good ideas but it could be a lot better.
>
> Here's how I'd build that sort of rx:
>
> First off, if a source of good 1700 kc xtals can be found, build crystal 
> filters for 1700 and eliminate the conversion to 100 kc and all the hard to get 
> IFTs. Perhaps a variable bandwidth ladder filter as used in the Elecraft rigs? 
> Or perhaps package the filters as subassemblies, with one for CW and one for 
> SSB, or even more.
>
> Moving the selectivity closer to the antenna will improve the dynamic range, 
> and simplify the rx. 
>
> Next, I don't know if I'd use a 7360 as shown, or in a balanced circuit. 
> Maybe try a different beam-deflection tube like the 6JH8 or 6ME8, or maybe a 
> Pullen or other triode mixer. In fact a receiver like that might be a good test-bed 
> for different mixers.

This was still in the every-construction-project-must-use-a-7360 phase,
I think! Yes, you're right, it isn't automagically the only mixer possible.

I think I once found a handbook SSB transmitter that used not one, 
not two, but three 7360 tubes!

> I'd build the VFO as a unit, rather than on the chassis, and I'd include some 
> kind of buffering/isolation. Maybe an ARC-5 tx capacitor with built-in dial 
> drive. Since the VFO tunes just one range, why not unitize it?
>
> The dual diode product detector could probably be replaced by an active 
> tube-type detector that would have some gain, easing the requirements for audio 
> gain. I'd use a bigger chassis in order to have more room and a bigger panel. A 
> balanced mixer in the converter (maybe a beam-deflection tube?) to eliminate IF 
> feedthrough problems mentioned in the article. 
>
> An interesting feature of the design is that it covers the WARC bands as-is, 
> with a little creative use of the preselector tuning and the bands tuning 
> backwards.
>
> To receive 30 meters, (I'm assuming the converter tuned circuits will tune 
> down to 10 Mc., or can be modified to do so),  select the 15 meter xtal (14.0 
> Mc.) and peak the 7360 grid circuit for 80 meter reception. 10.1 will show up at 
> 3.9 Mc. on the dial and 10.15 will show up at 3.85. WWV at 10.0 can be tuned 
> in at 4.0 on the dial.
>
> To receive 17 meters, select the top-end-of-10-meters xtal (22.0 Mc.) and 
> peak the 7360 grid circuit for 80 meter reception. 18.068 will show up at 3.932 
> Mc. on the dial and 18.168 will show up at 3.832. 
>
> To receive 12 meters, select the bottom-end-of-10-meters xtal (21.1 Mc.) and 
> peak the 7360 grid circuit for 80 meter reception. 24.890 will show up at 
> 3.790 Mc. on the dial and 24.990 will show up at 3.890.
>
> Of course one could add xtals and get the WARC bands to line up nicely, but 
> that means more quartz and extra coils.

Wow, that's a lot of bells and whistles :-). You are right, in that
as published the HB-65 design is less modular and less step-by-step
than many of the HBR's.

Tim.