[HBR] Explanatory Footnote

[hbr@mailman.qth.net]

Hi Jim,
> I never understood the need for S meters and AGC. But then, I'm from the
> W2LYH school of homebrew, anyway. 

S-Meters are mostly a ham cultural thing I guess -- but somewhat 
useful for checking receiver performance and such.   I think of this as 
a homebrew set that I might actually use pretty regularly, so the 
convenience of AGC is important.

> > The T1 has a
> > separate power supply but there's probably room to add it on the
> > chassis.  

> Ugh. Keep the PS and it's heat, weight, mag fields and vibration separate.
> Also permits use of one PS with several projects. 

Those are factors.   Again, a receiver that gets regular use probably 
needs its own power supply. 

The power supply box in the FT-101 is heavy gage steel -- not that 
much in the way of fields gets out.  (And I wouldn't expect problems 
from magnetic fields anyhow, except with a beam tube.)  It's open 
top and bottom, so as long as you don't fill it solid, it's pretty well self-
ventilating.  

> > However the T1 
> > is a 'value' set <snip>  but considering the labor invested
> > in any homebrew receiver and the fact that the two sets sell in the same
> > price range as 'parts only' units, I think the FT- 101 is a better
> > choice.  
> 
> Agreed! Both are Yaesus anyway - T1 was actually the FT-200 in disguise.
> No provision for any filters other than the SSB one, either. Nice dial,
> tho.

Since the T1 uses a 9 Mcs filter you could probably find the other 
filters but the FT-101 is easier, obviously.

> > Power supply -- a 35 VA 120-120 isolation transformer feeding two
> > half wave rectifiers supplying + and - 140 volts or so.  No
> > regulation.   Filaments are a Radio Shack 12V/3A transformer.  
> > Another Radio Shack transformer is used as a filter choke.  Mounted
> > in the box or external?  All in the box.   It's not even excessively
> > tight. 

> May be hot, though.

Actually, it's fine.   The secret is to keep the total power down and 
the secret of that is keeping the plate voltage down.   With full load 
the B+ voltage is about 140 or so; total current drain 110 MA.  You 
can touch anything in the set -- even the 6AQ5s -- because they're 
run well below full capacity.   Total power consumption about 40 
watts.  The transformers get up to 110-120 degrees.   
  
> I'd say each technology has its advantages and disadvantages. An Elecraft
> K2 has an excellent solidstate rx and uses less power than a 12BH7's
> heater doing it! But that's just one measure of performance. 
> 
> A big part of homebrewing today is to make something that cannot be
> bought, rather than imitation of what Ikensu has on the market. 

Agreed.   

> > But first, to finish this project.
> 
> And get mine started.

There you go!

Walt Hutchens
KJ4KV