[HBR] RE: HBR 2006 and a question

[N2EY at aol.com]

In a message dated 4/9/06 2:37:57 PM Eastern Daylight Time, 
windy10605 at juno.com writes:


> Apparently the HBR was the right receiver at the right time judging from
> all the people who built them and the interest which remains today. 

I wonder how many were actually built?

In the early 1960s there were about 250,000 US hams, mostly (at least 75%) 
Generals, Conditionals and Advanceds.

It
> 
> allowed home builders to try a "more complex" design and come up with
> something which was really useful for day to day operation vs being put
> on the shelf. 

I think the big attraction was that they were general-purpose all-band HF ham 
receivers that were extensively documented and 'buildable'. HBRs were more 
complex than regens or simple supers (and outperformed them) but not so complex 
as to require extreme skill/experience in construction. Nor did they use 
unusual parts. And they were easy to modify - note that W6TC didn't originally use 
the 898 dial - that was an adaptation by another.

Most of all they practically screamed "BUILD THIS RADIO" and "YOU CAN DO IT" 
at you from the magazine pages. 

>  I still wonder why HFO heterodyning was not selected vs fighting
> HF Oscillator stability. Maybe Ted addressed this in one of his letters ?
> Maybe he was just an L/C man ? Maybe he had some bad design experiences
> with crystals ? 

The problems with premixer LO:

1) Spurs. You have to worry about any unwanted outputs from the premixer. 
Even products that are many dB down can still wreak havoc. Coming up with such a 
design for 5 bands isn't easy.

2) Complexity. You need another oscillator, another mixer, and a bunch of 
filters - all of which change on each band.

3) Cost. Non-ham-band xtals were expensive back then, and a bunch of them and 
the added stages would add a lot to the receiver price. $6 each may not seem 
like much now but 40+ years ago it was a fortune. This may be why the HBR 
avoided the 'hottest' new tubes and circuits of the time. For example, the 7360 as 
a product detector was all the rage in some circles, but it cost $3.95 for 
the tube, compared to half that or less for a 6BY6. Was the improvement worth 
doubling the price of the stage? 

A lot of expense could have been spared by using surplus and non-current 
parts, like IFTs and the three-gang cap/dial from ARC-5s, older tube types that 
were inexpensive, etc. Surplus xtals could have been used in filters and 
heterodyne schemes. But doing so would have violated the 'no surplus, no old parts' 
concept that was a feature of all W6TC designs. 

Yet all of the HBR designs use very conventional circuits and parts. They're 
wide open for modifications and substitutions. No trick circuits or fancy 
gadgets, just straightforward classic design. 

4) Alignment Fuss. Self explanatory


I know he had strong opinions (and expressed them) about
> 
> using a 3500Khz calibration crystal vs the "standard" 100Khz. 

With a 100 kHz IF, he couldn't use a 100 kHz calibrator - you'd hear it 
through the IF unless the shielding and isolation were very very good.

Problem with the 3500 cal xtal is that it only gives you one marker per band, 
and it's at the low end. Fine for CW DX types but the 'phone folks better 
have another standard.

Plug in
> 
> coils are an excellent idea vs bandswitching because of the reduced
> complexity, shorter wiring in the critical frontend, less space required,
> the possibility for larger coils which improves "Q", etc ....lots of
> advantages and only one convenience disadvantage.
> 

They also avoid the trouble and cost of finding exactly the right bandswitch 
assembly. the mechanical work of installing and shielding it, and the 
inflexibility of layout it forces on you.

Plug in coils also permit a lot of experimentation. Some HBR folks built 
coils for SWBC, coils for use with VHF converters, coils for WWV, etc. If an HBR 
owner could get the forms, coils for the WARC bands could be wound. What other 
rx design would allow the addition of new ham bands decades after the original 
design?

I think the real glory of the HBR design, and the true legacy of W6TC, is 
that he really upset the apple cart of homebrew at the time. Even before WW2, 
receiver building by hams was in decline as more and more hams bought their 
inhalers. Note how many more models of receivers there were than transmitters in 
those days, even though the postwar receiver market had to compete with surplus. 
By the mid 1950s, the Conventional Wisdom of many hams (in the USA, anyway) 
had become something like 'modern receivers are too complex/expensive to be 
homebrewed anymore'. 

Look at how many 'beginner' receiver designs there are in the ham mags and 
handbooks - and how few 'serious' designs, until TC showed the way.
 
Yes, there were other receiver builders, like my own homebrew Elmer, W2LYH. 
But most of those designs were specialized or relied heavily on surplus parts 
and builder know-how.

Also, the HBRs were what TC wanted them to be. They included things he valued 
and left out things he didn't. That's a lesson for all of us! For example, a 
much more stable design could have been obtained several ways, but TC didn't 
think it was worth the tradeoffs.
 
73 de Jim, N2EY