I picked up a Drake R7 this week. I upgraded the 1st mixer to an SRA-3MH and
changed the diodes in the 2nd mixer and the translater mixer to matched
1N5711 hot carrier diodes (I don't know why they used 1N4148s in the first
place).
Anyway, this is where the story gets sadder. When I replaced the DR7 control
board the LED display worked for about 20 minutes, and then it died. I can
still toggle up and down through the 500kHz steps so the synthesizer is
still working but I am not sure what controls the display. +5V seems to be
present at the different chips. I don't know if that display driver chip
took a dive.
Has anybody else had this type of problem?

Pete

In article ,
"Pete KE9OA" wrote:

I picked up a Drake R7 this week. I upgraded the 1st mixer to an SRA-3MH and
changed the diodes in the 2nd mixer and the translater mixer to matched
1N5711 hot carrier diodes (I don't know why they used 1N4148s in the first
place).
Anyway, this is where the story gets sadder. When I replaced the DR7 control
board the LED display worked for about 20 minutes, and then it died. I can
still toggle up and down through the 500kHz steps so the synthesizer is
still working but I am not sure what controls the display. +5V seems to be
present at the different chips. I don't know if that display driver chip
took a dive.
Has anybody else had this type of problem?

Another problem is that you replaced a 500 mW diode with a 250 mW diode
so have you checked to see if they are still good? Maybe they shorted
and took out a bias supply that is also used for other things like a
logic signal control voltage.

--
Telamon
Ventura, California

In article ,
"Pete KE9OA" wrote:

I picked up a Drake R7 this week. I upgraded the 1st mixer to an SRA-3MH and
changed the diodes in the 2nd mixer and the translater mixer to matched
1N5711 hot carrier diodes (I don't know why they used 1N4148s in the first
place).
Anyway, this is where the story gets sadder. When I replaced the DR7 control
board the LED display worked for about 20 minutes, and then it died. I can
still toggle up and down through the 500kHz steps so the synthesizer is
still working but I am not sure what controls the display. +5V seems to be
present at the different chips. I don't know if that display driver chip
took a dive.
Has anybody else had this type of problem?

Some decoder chips have an enable pin. What is the part number?

--
Telamon
Ventura, California

I have a TR7 that has intermitent display, and I believe its just bad
contact on the plug in boards. Not sure if r7 is buit same way, but might be
worth a try re seating boards.

Chuck (W3FJJ)



In article ,
Pete KE9OA wrote:
I picked up a Drake R7 this week. I upgraded the 1st mixer to an SRA-3MH and
changed the diodes in the 2nd mixer and the translater mixer to matched
1N5711 hot carrier diodes (I don't know why they used 1N4148s in the first
place).
Anyway, this is where the story gets sadder. When I replaced the DR7 control
board the LED display worked for about 20 minutes, and then it died. I can
still toggle up and down through the 500kHz steps so the synthesizer is
still working but I am not sure what controls the display. +5V seems to be
present at the different chips. I don't know if that display driver chip
took a dive.
Has anybody else had this type of problem?

Pete

Thanks guys.....................I am going to fool around with it a little
bit more this afternoon. I do have a soft copy of the service manual, so I
will study it.
About those diodes I replaced, they are used in the mixers and they are run
in switch mode from the LO signal, so there is no power supply providing
bias to these components.
It was worthwhile to make these improvements...........with a short antenna,
there is no difference in signal to noise whether you have the preamp
switched on or not.

Pete

"Chuck Hanavin" wrote in message
...

I have a TR7 that has intermitent display, and I believe its just bad
contact on the plug in boards. Not sure if r7 is buit same way, but might
be
worth a try re seating boards.

Chuck (W3FJJ)



In article ,
Pete KE9OA wrote:
I picked up a Drake R7 this week. I upgraded the 1st mixer to an SRA-3MH
and
changed the diodes in the 2nd mixer and the translater mixer to matched
1N5711 hot carrier diodes (I don't know why they used 1N4148s in the first
place).
Anyway, this is where the story gets sadder. When I replaced the DR7
control
board the LED display worked for about 20 minutes, and then it died. I can
still toggle up and down through the 500kHz steps so the synthesizer is
still working but I am not sure what controls the display. +5V seems to be
present at the different chips. I don't know if that display driver chip
took a dive.
Has anybody else had this type of problem?

Pete