[HBR] HBR2K Chapter 8 -- It Works!

[hbr@mailman.qth.net]

Well, mostly, anyhow.  

No kidding, it's sitting on the bench tuned to WWV, doing just fine.  I 
hear WWVH too.

The last big piece was installing and wiring the bandswitch and RF 
stage.   Tricky, because the last wiring is in a pretty tight space.  
There were actually very few real problems -- most was just wiring 
errors and blobs of solder in the wrong place, found by inspection.

The worst of the actual problems was pure nut-behind-the-tuning-
knob kind of stuff -- I forgot to hook the RF state to the first mixer and 
couldn't figure out why the sensitivity was so low.   

The only other was the trap for leakage on the first IF (World Harvest 
Radio on 5825) located between the cathodes of the RF stage, didn't 
work.   I had the circuit wrong ... 

There are two traps on that band, and two is none too many -- boy 
are those stations strong, at this location.   I'll probably add a third 
trap -- it could be done between the 1st mixer cathodes, I believe.   

There are some problems to solve.   The RF stage oscillates at the 
extreme low end of the tuning range.   No idea what that problem is.   
There is a small amount of drift -- maybe 100 cps/hour? -- during the 
first hour of warm-up.  Not much, but it's absolutely steady and it 
seems a shame not to cut it down some more.  I may have noticed 
some pulling of the VFO -- did not have a good signal source or test 
setup, so I'm not sure.  It could also be variation of VFO frequency 
with B+ -- nothing is stabilized.   I believe there is some audio 
distortion.  The S-meter full scale adjustment is wired so the pointer 
moves the wrong direction.   The RF gain control does not have 
sufficient range.  

And some features aren't there yet.   The filter switching 
(SSB/AM/CW) isn't wired -- all testing so far has been with the SSB 
filter.  The calibrator isn't wired.   There's no noise limiter -- though in 
truth I rarely use them even on receivers that are equipped.   There's 
no provision for calibrating the S-meter.

A good alignment and optimization of signal levels needs to be done. 
  
The last hour as I've been writing and listening to WWV/H by zero 
beating it has stayed in a 5 cps range -- that's good enough.

Gee -- I need to get busy on the diagram.   Does anyone know of a 
schematic-drawing software package that's affordable, easy to use, 
and has vacuum tube symbols built in?   

Walt Hutchens
KJ4KV