[HBR] Current day HBR

[Shoppa, Tim]

Pete writes:
> Folks often comment about the the lack of general coverage bandspread
> on Ted's designs.

Aha, here we come again to what I feel was genuinely the spirit of Ted's design.

The HBR-14/16 was a no-compromises ham-band receiver. It could also of course accommodate the SWL or any other fairly narrow HF bands with appropriate coil sets.

It is, by what I feel was Ted's intent, NOT a general coverage receiver. There are simply huge mechanical issues or electrical compromises, trying to get general-coverage-receiver type bandspread.

Again, I strongly feel that I'm channeling Ted here.

Even with modern technology (e.g. all the YaeComWood upconverting ham transceivers with a 45 or 60 or 90MHz first IF the past couple decades) there are substantial compromises made in receiver performance if you make it be general coverage. The current work-around to such limitations is called a "roofing filter". But folks talk about roofing filters as if they are the holy grail, when in fact they are a workaround for the fact that you have a upconverting radio with insanely high first IF.

I have nothing against winding a new coil set for an existing HBR-14/16 for SWL bands. In fact I'm pretty sure some of the QST articles or follow-ons show how to do this and I have such coils. But the HBR-14/16 is by nature a band-oriented receiver, not a general-coverage receiver. There are simply too many compromises made in making a general coverage receiver.

Again, this is a decision that any radio design has to make early on: high performance, or general coverage? You can't wibble-wobble without ending up with a crappy radio or spending massive amount of effort/money/mechanics. In the 50's and 60's this was most visible as tuning rate and LO stability, but today it is most visible as poor close-in dynamic range.

The massive amount of mechanics to avoid making the compromises in a general coverage receiver ends up looking like a R-390 if you use 50's technology. I have nothing against the R-390 or 390A, I have two 390A's myself, and it is a fine general coverage receiver. But obviously the geartrain is not a typical ham homebrew project, it would be a challenge for any professional watch or clockmakers with gearmaking abilities.

The problem is, hams want their ham radio to also be a general coverage receiver, and when they buy a receiver part of the spec is the frequency coverage, but the spec doesn't show (very well) the tradeoffs in making a general coverage receiver. This has led to poor HF radio performance the vast majority of hams for the past couple of decades, because it looks like general coverage receiver ability is a feature, when really it means compromises in receiver performance unless it ends up looking like a R-390 :-)

Tim.

On Mon, Jan 10, 2011 at 11:41 AM, <W6ph at aol.com> wrote:

> Some random thoughts:
>
> Plug-in coils are really the way to go.  But the plug-ins are rapidly
> becoming unobtainium.
> K5MO had a bunch of four, five, and six pin Meissner coils that he was
> selling.  I'm not
> sure if he still has them.
>
> One of the big concerns that Ted had was stability of the first local
> oscillator.  By building
> a single band HBR, the three front end coils could be hard wired in.  A
> really cool idea
> would be to pick up one of those 5-5.5 MHz Heathkit LMO's to use as the
> first LO for
> linearity and stability.  Combining that range with the 1415 KHz IFT's
> would give you
> 3585 KHz to 4085 KHz.  I haven't considered any spurs which might be there.
>  If you
> had the wherewithall to modify the 1415 KHz IFT's to 1500 KHz, you would
> have the
> entire 80m ham band.
>
> There seem to be quite a few choices for dials other than the Eddystone.
> One thought
> that I have had is to use the Jackson Brother verniers with a blank CD as a
> circular
> dial.
>
> One other comment.  There may be another Ted Crosby out there.  I have
> followed
> Walt Hutchens' postings over the years and have archived most of them for
> ideas.
> He might be the 21st Century Ted Crosby.
>
>                                    73, Kurt, W6PH
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