"nesesu" wrote in message
...
On Dec 1, 8:24 pm, "Lynn" wrote:
. Is there a soild state replacement for the rectifier tube 5U4 in a

HQ-145xc?

Seems I remember such a tube being available for around $20 from an
internet source.

73

John

The tube replacement always seemed like a good idea to me, so
back in the good old days, I did just exactly what many responders
here talk about.
I replaced the 5Y3 (I think) in my RME 4350 with a resistor and
a couple of nondescript silicon diodes (before the advent of the
extremely 1N4007), and after fidgeting with the voltage output
by adjusting the series resistor, found a new hash on the received
signal.
It's been a while, now, more than 40 years, but if I remember
correctly, I tried RF chokes, additional filter capacity, smaller
ceramic disk capacitors (condenser, actually, but what the heck)
and I finally went back to the original 5Y3 tube.
As I remember (and probably have the scars to prove it) the
voltage dropping resistor got pretty hot.... had to use a
wirewound resistor to handle the heat.

Old Chief Lynn, W7LTQ

Yes, that is a problem with the silicon diodes.
If it is a problem in any of the rectifier tube replacemnts, one can
connect series connected .001u and about 33 ohms across each diode.
The .001 should be rated for 3kV. keep the overall length of the R-C
and leads to less than 1 inch.

Neil S.

Well, that might have well worked! Didn't try that, I guess.
Isn't that something like what Decca in some radar pulse
circuits called a "tail biter"?

Old Chief Lynn