On Sun, 15 Jul 2012 11:15:27 -0400, Edward Knobloch wrote:

On 7/15/2012 1:15 AM, coffelt2 wrote:
I've never used a purchased solid state replacement, but in days of old
many of us tried a do-it-yourself replacement. Most had good results. I
didn't. I don't recall using a dropping resistor as Ed suggests, but it
sounds ok. What I had problems with was the solid state diodes I was
using had a much sharper cut-off (reverse current cut-off)
that generated a little RF hash that interfered with weak signal
reception. There were others that experienced the same thing. I was not
alone. My RME 4350 ran hot, alright, but propping open the hinged
access door on top helped a lot. Ed, what did others do to stop the
sharp cut-off hash?

Old Chief Lynn


Hi, Chief

In case of increased hash with the solid-state rectifier replacement,
I'd add two .01 disc ceramic capacitors to the 5U4 socket, across pins 4
and 2 and 6 and 2. The capacitors should be rated at 2 KV.

73,
Ed

Thanks for all the good advice. It seems like I would just be better off
keeping the tube! I knew that guys on this group would come through with
the solution.

On Mon, 16 Jul 2012, Bob Grimes wrote:

On Sun, 15 Jul 2012 11:15:27 -0400, Edward Knobloch wrote:

On 7/15/2012 1:15 AM, coffelt2 wrote:
I've never used a purchased solid state replacement, but in days of old
many of us tried a do-it-yourself replacement. Most had good results. I
didn't. I don't recall using a dropping resistor as Ed suggests, but it
sounds ok. What I had problems with was the solid state diodes I was
using had a much sharper cut-off (reverse current cut-off)
that generated a little RF hash that interfered with weak signal
reception. There were others that experienced the same thing. I was not
alone. My RME 4350 ran hot, alright, but propping open the hinged
access door on top helped a lot. Ed, what did others do to stop the
sharp cut-off hash?

Old Chief Lynn


Hi, Chief

In case of increased hash with the solid-state rectifier replacement,
I'd add two .01 disc ceramic capacitors to the 5U4 socket, across pins 4
and 2 and 6 and 2. The capacitors should be rated at 2 KV.

73,
Ed

Thanks for all the good advice. It seems like I would just be better off
keeping the tube! I knew that guys on this group would come through with
the solution.

The solid state replacement doesn't use filament power, so the load on the
transformer is less.

Michael VE2BVW

Michael Black VE2BVW wrote:
The solid state replacement doesn't use filament power, so the load on
the transformer is less.

Yes, and will result in 15 Watts less heat in the cabinet
with the 5U4 gone. Stability will be improved
and warm-up time reduced. Just don't forget
to add the 200 Ohm resistor to bring the B+ back to normal.

73,
Ed Knobloch