[HBR] Another HBR Project -- Chapter 2

[hbr@mailman.qth.net]

One virtue of a simpler design ought to be shorter posts.   We'll see.

The 'something more like the traditional design' has turned out to be:

6EH7 RF
6ES8 1st mixer -- 1665 kcs
6BH6 1st oscillator (tunable)
6ES8 2nd mixer -- 85 kcs
1/2 6U8 2nd oscillator 1750 kcs
6EH7 IF -- 85 kcs
1/2 6U8 BFO -- 85 kcs
1/2 12AX7 plate detector/product detector
1/2 12AX7 AGC amp (basically another plate det.)
1/2 6U8 1st audio
1/2 6U8 phase splitter
12BH7 2nd audio 
1/2 6U8 100 kcs calibrator

The 1665 kcs 1st IF was chosen because I have a 1750 kcs crystal.  
(Because the harmonics are on the edges of several bands, that's 
not ideal and I'll switch to something lower when I find the right 
crystal.)   Two 1415 kcs command set transformers will be converted 
to serve; there'll be space between them to add another IF stage if 
needed, but I don't expect I will.   The 6EH7 has about three times 
the gain of a 6BJ6 and (in my opinion) the original HBR designs had 
more gain than needed.

Front panel controls PWR, STBY, BFO, BFO TUNE, CALIB ON, 
PHONES, CALIBRATE (trimmer), pilot lamp, RF GAIN, AUDIO 
GAIN.   

Should have the major parts mounted by tomorrow night.    Pix then.

Walt 
KJ4KV

The chassis hole-making is done but one, the front panel is laid out 
and should be done today.