[HBR] RE: HBR 2006 and a question

[N2EY at aol.com]

In a message dated 4/10/06 1:28:14 PM Eastern Daylight Time, 
waltah at earthlink.net writes:


> It's just about impossible to fault this design for the 'market' that Ted 
> Crosby was trying to reach.   

Well, I'll agree on some points and disagree on others.

Others have listed the main points: parts off 
> 
> the shelf from standard sources, performance comparable to the upper-
> middle price range receivers of the time except for the lack of 
> bandswitching, lack of any critical circuits or difficult adjustments, ease 
> of extending by winding other coils, using a better dial, substituting used 
> parts if desired (85 kcs 'command set' transformers vs. 100 kcs Millers, 
> command set tuning cap ...), and more.
> 

Yup. 


> EVERY design incorporates some compromises.   The W6TC receivers accept 
> the inconvenience of plug in coils and higher warm-up drift than can be 
> achieved with a fixed-coil or partly-crystal controlled front end but they 
> deliver a BUILDABLE receiver that would make QSO's as well as what most 
> hams could have bought at the time and better than most of them.   

A lot depends on which tradeoffs you prefer.

It would be interesting to know how much the various HBRs cost to build from 
new parts back when they appeared. The 898 dial, for example, cost about $21 
new, which works out to maybe $100 in today's money? 

A total-cost estimate would be needed before you could make an honest 
comparison.

The $269 Drake 2-B appeared about 1963 IIRC. Perhaps it should be the 
standard of comparison?

 The 
> 
> things have a potfull of front panel controls but nearly any tube that would 
> 
> light up will work fine (where most ham designs assume new tubes) and you 
> could optimize the gain distribution for either weak signals or crowded 
> band/many strong signals.
> 

Agreed.

> The 3500 kcs crystal band edge marker was perfectly adequate for the 
> operational calibration of these receivers; you couldn't read the dials 
> closely enough to require any more than a band edge check when changing 
> coils, anyway.   And there were the advantages of no problem getting a 
> strong calibration signal nor of identifying what signal you had, since only 
> 
> one would be heard per set of coils.   
> 

It seems a lot of work for one cal point per band. 100 kc wouldn't work 
because of the IF. But 250 kc would work, and would give at least two cal points 
per band.


> Look at the 'simple receiver' designs of the 60's Handbooks:   All of them 
> with more than three tubes will outperform the HBR-series on one or more 
> points, most often selectivity.   But they're nearly all so limited in some 
> other area that they're closer to "an experimenter's receiver with which you 
> 
> could make some QSOs" than "a station receiver with plug-in coils."   

I disagree!

They're simply aimed at a different set of compromises. 

 Take 
> 
> the 'Advanced 6-Tube Receiver' of the 1969 handbook as the best of 
> breed: Single conversion on 80 with a crystal controlled converter for other 
> 
> bands -- not too bad so far.   The mixer is a 7360.   But audio AGC and no 
> way to switch off the BFO make it useful only for SSB/CW.   Sorry, that's 
> not a station receiver.  

Why not?

By 1969, AM had become a specialty mode on the HF ham bands. The HBR-8 
doesn't have AGC or a diode detector, either! 

The reason for so many audio AGC designs in those '60s receivers is simple: 
the audio hang AGC circuit worked well enough for the designers, and it was a 
bit of a job to keep the BFO signal out of the AGC chain if you did IF-derived 
AGC.


 With a Collins mechanical filter for selectivity, it's 
> 
> not inexpensive, either -- or even 'moderately priced.'
> 

How much did the specified filter cost in those days? IIRC, later models used 
a Lafayette mechanical filter that wasn't very expensive. \

The proper Miller 100 kc IFTs and BFO weren't inexpensive, either.

> The only real station receiver is the DCS-500 of 1960 +/-.  

What about W2LYH's "Sectionalized Communications Receiver"?

I think it all depends on how you define "station receiver", though.


 That's a decent 
> 
> design (also using plug in coils) but  requires four crystals ('surplus') 
> for 
> selectivity plus one more in a transistorized 100 kcs calibrator and has 
> modified IFTs and some relatively complex/critical circuitry. 

Those IFTs are inexpensive TV width coils. The 4495 xtals are obviously 
surplus (thereby violating that rule!) and are a probably the first example of a 
"roofing filter" in a ham receiver!

The DCS-500 was obviously inspired by the HBR series. The only really big 
difference is the IF methods. Even the layout is similar. 

  The main 
> 
> thing you get in exchange for much less 'buildability' is several steps of 
> variable selectivity -- a poor trade-off, in my opinion. 

Is the DCS-500 that much harder to build than an HBR? Sure, there's the 
bandwidth switch, and the modified width coils, but the rest is all the same. 

The HBR tradeoff was to settle for one IF selectivity setting for all modes. 
That's quite a tradeoff, unless you only use modes that match the bandwidth 
chosen. Audio selectivity just doesn't cut it unless it's a backup to good IF 
selectivity. IMHO, the lack of attention to mode-appropriate selectivity was a 
major tradeoff in the HBR designs.

  There's no product 
> 
> detector, so receiving SSB would require you to use the old technique of 
> backing down the RF/IF gain and in this design that requires switching off 
> the AGC.   
> 

Ture, but that's easily fixed. Many of the HBR designs (HBR-14, HBR-8) are 
the same way.


> Yes, the design glitches could be fixed.  

They weren't glitches - just different tradeoffs. 


 But if you're qualified to do that, 
> 
> you don't really need a Handbook design, do you?  

The DCS-500 wasn't a Handbook design - it originally appeared in QST.

I have often thought that Handbook projects had two distinct purposes:

1) They were buildable projects at various levels of complexity, from raw 
beginner to quite advanced. They weren't state-of-the-art as much as 
tried-and-true.

2) They demonstrated concepts and practices. Complete systems, not just 
partial circuits. 

Improving the AGC of the DCS-500, and adding a product detector, would be 
simple changes that could be done after the receiver was complete. Adding 
variable IF selectivity, or even decent CW selectivity, to the HBRs would not be!

 The DCS-500 is 
> 
> basically a fine 1950 station receiver design realized with 1960 parts.
> 

How is that any different from the HBR series? There's nothing in the HBR 
designs that wasn't available in 1950. 

If there's anything wrong with all those Handbook receivers, and the HBR 
series too, it's that they seem to have all forgotten about CW operation. Almost 
all of them assume that SSB selectivity is fine for CW. Except for the DCS-500, 
none of them have good-enough CW selectivity. Many don't have AGC or an S 
meter that will work with the BFO on, and those that do, usually depend on audio 
AGC. 

I think one of the main reasons some hams have/had difficulty with CW is the 
lack of decent inexpensive receivers for the mode. To give just one example, 
look at the popular Heath HR-10. Then look at the receiver section of the 
HW-16. 


> All those handbook receivers uses unbuffered triodes as local oscillators.  
>  
> It's not easy to do that without getting enough oscillator pulling to reduce 
> 
> intelligibility of a sideband signal, and they don't; the 'Advanced 6-Tube 
> Receiver' (7360 mixer with the LO driving the deflection plates) might be 
> satisfactory.   The W6TC ECO LO does not have the problem.

I've always wondered why so many otherwise-good receiver and converter 
designs used the same old triode-tickler oscillator circuit, without even a cathode 
follower buffer. It seems like much of what was learned about transmitter VFO 
design was forgotten when receivers were designed.

The W2YM VFO makes a dandy receiver oscillator.

   All except 
> 
> the DCS-500 are single conversion designs but you have to build a crystal 
> controlled converter if you want more than one or two bands.   
> 

The crystal-converter front end idea is a very good one - the Drake 2 series 
all use it. Besides its obvious electrical advantages, it simplifies the 
construction by breaking it down into parts. Get the 80 meter section working, then 
go for the converter. 

The HBR series required winding and adjusting a set of coils for each band, 
and calibrating the dial for each of them. A lot of work and expense! With a 
crystal controlled converter, you do the job once for 80 meters, and done.


> Look beyond the handbooks and there are exactly two serious candidates 
> for a home built station receiver:   the G2DAF sets which are close to the 
> complexity of the Collins S-Line receivers (but EXCELLENT), and the 

> premixed design of W5OMX, Col. Dave Curtis.   

What about W2LYH's receiver that I mentioned above?

Or the "Miser's Dream" of 1965? 

--

I think we would have seen a lot more G2DAF receivers on this side of the 
pond except for two factors:

1) they didn't get a lot of publicity compared to other designs

2) they used a good number of parts and tubes not familiar to US hams

There's NO chance that you 
> 
> could build a two tube project and then tackle either of these with a good 
> chance of success -- and the price would have been in the ballpark of a 
> used Collins A-line or Drake receiver.   
> 

How about a receiver like this:

http://www.qsl.net/k5bcq/Jim/SilverRX1.jpg

I think cost is one big factor what really killed off a lot of homebrewing. 
How much *did* the HBRs cost to build from new parts, compared to, say, a 2-B 
or an SB-300? And what would the resale value be?

The other factor was the move to transceivers, which also helped put SSB over 
AM in a big way. A transceiver like the SB-100 cost about 150% of the price 
of a similar receiver - but it transmitted too! 

> W6TC was a gifted radio designer.  

No argument there! But his designs involve *his* choice of tradeoffs.

---

Now for something slightly different:

What constitutes a "station receiver"?  

73 de Jim, N2EY