[HBR] Help with old home-brew receiver

[hbr@mailman.qth.net]

Wow, a feeding frenzy among the HBR vultures!   This sure is more 
exciting than making the next yard-and-a-half on the HBR2K project!

Jim:
> All good possibilities. Another is that the noisy 6BE6 first mixer was
> replaced by a 12AU7 a la Pullen, and the 6BY6 added as a product detector.
> Or the 12AU7 may be the product detector. 12AU7 could also be a tube to
> drive an S meter (external?)

This seems a better bet than my ideas.   If I were doing it with those 
tubes I'd make the 12AU7 the first mixer, a la Pullen (dual triode 
mixer with particular operating conditions) and use the 6BY6 as a 
product detector.   Among other problems this solves, the 6C4 local 
osc really needs more isolation than feeding a 6BE6 directly -- I don't 
think it's possible to get good SSB reception above 10 Mcs with 6C4-
6BE6 lineup.

I once converted a 3-6 Mcs command receiver to dual conversion 
using one of the original 1415kcs IFTs and two 85 Kcs ones.   It 
worked fine, tho just a little more gain would have been desirable.   
Actually, something along that line might also make a good HB 
project.   With the frame grid tubes you'd have plenty of gain.

That could even be a way to go for a simple general coverage home 
brew receiver -- just have to add a converter in front of it for the 
successive bands.

Back to the 9-tube receiver.   Power supply -- a pair of Radio Shack 
12 volt 3 amp filament transformers back to back with filaments fed 
from the center and the second primary bridge rectified would give 
you around 160-70 volts; the radio should work okay and the slightly 
lower voltage would be kinder to the command set caps.   Ground 
the center tap of the 'input' transformer and divide the receiver 
filaments into two strings.   I am running the HBR2K project receiver 
(vacuum tube dual conversion receiver designed around an FT-101 
chassis and parts) at 145 volts with no problems.

But maybe you already have a power supply.   Anyhow, let us know 
how it goes!

Walt Hutchens
KJ4KV