[HBR] HBR 2000/11 Comments?

[Tuchueh7 at cs.com]

Things move mighty slow here at the KC8LTD workshop...Progress to date: A 
170vdc
at 200mA power supply has been built on a small chassis along with a 
5879/6CW5
audio amp. Used a 6.3v 3A fil. transformer for the output iron. Plenty of 
power to drive
a six inch commercial PA speaker in an open back cabinet and it is LOUD!! 
Sounds like a good old AA5 on steroids, complete with a little hum. The power 
supply is a 
full wave choke input, the choke is a trifle low inductance-wise and I had to 
add a little
cheat. An IRF820 hexfet in a capacitance multiplier configuration cuts down 
the excessive ripple and as a bonus, brings up the B+ slowly. The whole shebang 
is housed in a mitered solid walnut box. Looks great!!!
       Still thinking about the 100kc. IF strip. I was able to tame the 
455kc.6EH7 breadboard by capacitance bridge neutralization. The problem here is to 
find really
tiny fixed neutralization caps. 5-10mmf requires a gigantic variable (like 
2000mmf)
in the other leg. I just hardwired a bunch of large silver micas until I got 
it right. Looking through the junkbox, I found some of those old ceramic (?) 
low capacitance
parts that were found in 1950's FM tuners. They look like 1/2 watt resistors 
(only shorter) Does anybody know anything about these? Reading the color code? 
Note:
these are NOT the "dogbone" ceramic units that were ubiquitous in high 
frequency
gear a few decades ago.
       Also thinking about the plug-in coil situation. Admittedly, plug-in is 
the simplest
and most straight forward solution, but I like to skip from band to band and 
am apt
to operate at no particular time of day. Therefore the plug in coil is not 
very attractive.
Reed relays are going to require some real topological planning in order to 
avoid excessive lead length and stray capacitance. Attention to the materials 
used in the reeds is also in order. I will need to make up another test 
breadboard to evaluate
how they perform in an oscillator circuit. I will also need to isolate the DC 
coil control
signals with wire chokes. So thats the story from here so far. Thanks to all 
for the
comments