[HBR] Another project?

[N2EY at aol.com]

In a message dated 9/21/06 4:53:57 PM Eastern Daylight Time, 
waltah at ntelos.net writes:


> Like the G2DAF sets, the G3RKK design was published in the RSGB bulletin
> and in the 3rd edition of the RSGB Radio Handbook.  It is said to have 
> been constructed in considerable numbers.  I had never heard of it until 
> I bought this example.

It's shown in my 4th edition of the RSGB Handbook, too. It's definitely a 
simpler project than a G2DAF.

> 
> The G3RKK is similar to the W6TC designs in being double conversion
> using fixed IFs of 1620 and 85 kcs.  The big difference is the use of a
> bandswitching front end instead of plug in coils.   BUT the front end
> assembly (separate subchassis about 7" x 7") was available as a
> pre-wired assembly from Electroniques -- a UK company.
> 

I get the impression that Electroniques was the big name in GB homebrewing 
then - sort of a combination of Miller and B&W here.  Almost all of the Handbook 
projects use some of their components.

> Buildability-wise this is not quite the equal of the HBRs -- there are
> several shields

ahem...."screens"


 under the chassis and other non-trivial work -- but the 
> 
> use of a prewired front end with no coils to wind probably made it even 
> easier for some builders.
> 

In the back of my 4th edition is an advertisement - er..."advert"...from a 
metalworks that offers to supply completed sheet metal for the G2DAF and other 
projects. It looks like one could order a complete set of all the pieces, or 
just those that were hard to fabricate at home, like a heavy-gauge front panel 
with the special cutout for an 898 dial. No prices given. Lovely picture of a 
G2DAF rx, too.

Between the prewired front end and fabricated metalwork, the G3RKK could 
start to look like a semi-kit. 

> I suspect that both stability and performance were somewhat below the
> HBR-series sets.  The coils are necessarily much smaller -- maybe 3/8" 
> diameter? -- meaning lower Q.  They're on nylon forms -- excuse me, 
> *formers.* 

Quite right!

 Drift could be better or worse than the HBRs, but probably 
> 
> not greatly better, in fact the Radio Handbook says there was a later 
> version that (among other things) reduced the drift on the higher bands.
> 

The 4th edition specifies that the drift would be no worse than 500 Hz per 
hour after warmup, even on 10 meters. 


> (The improved version is said to have been described in an issue of the 
> RSGB Bulletin; I wonder if anyone has a lead to that article?)
> 

The 4th edition mentions it, but says the modifications are complex and 
sticks to the basic design. So it's not in the 4th edition either.


> The circuitry is 'very conventional' -- diode detector for AM, dual 
> triode product detector for SSB, single ended audio, no Q-multiplier in 
> the front end.
> 
> Except for the factory-built front end assembly which is in decent 
> shape, the metalwork and wiring on my example are poor.  But all the 
> critical parts are there, including a pre-calibrated Eddystone dial (I 
> expect the printed dial scale came with the front end chassis), that 
> bandswitching front end, the tuning cap and the IFTs.  So it could be 
> turned into a kit with no more trouble than you'd expect.


AMAZING! 

The Electroniques front end was described as coming pre-aligned from the 
factory, similar to what Heath did with the Mohawk.

The 85 kc IFTs aren't Command-set surplus - they were made by Electroniques, 
too. I suspect there may have been substitutions made, though.
> 
> 
> Gee ... a $350 reserve.  But the marketplace says that's realistic.  I
> wonder what the guy's actual bid was?  $400?  $500?
> 

When I think of the hamfest units I passed by 20-odd years ago, or sold for 
peanuts....sigh....

Then again, the reason such things bring high prices is in part due to their 
rarity. And that '16 is excellent.

I wonder what an HBR-16 cost to build 40-odd years ago - and what that 
equates to in today's dollars.

Also wonder what our homebrew projects will be selling for in 2046....

73 de Jim, N2EY