Hint on replacement for Yaesu panel lamps
 

My Yaesu FT-4700RH had 4 "grain of wheat" style lamps
to provide panel/display backlighting. 3 of them had burned
out. These lamps are accessible from the back of the removable
control head. They are covered with pliable orange plastic covers
and inserted through holes in the PCB from the back side, with the
two leads bent over and soldered to pads on the back side of
the PCB, so they are easy to remove. (Save the orange plastic
covers to use on the replacement bulbs.)

To my pleasant surprise, I found that RadioShack's
SKU 272-1092 (pkg of 2) were a physical fit.

The lamp driver circuit in the FT-4700RH runs from 9V
controlled by a PNP driver that is driven by a circuit that
allows "bright" and "dim" (controlled by a front panel
switch labeled "dim").

The RadioShack "micro lamps" are labeled as 12V 60 mA,
and are not *quite* as bright as the original Yaesu part, but
they are (IMHO) adequately bright, and should last a long
time with the derating resulting from the 9V supply and the
fact that there is a 4.7 Ohm resistor in series with each lamp.

Cost - about $6.00 for four packages of two lamps (I bought
spares).

I hope that someone finds this useful - the same lamps *may*
have been used by Yaesu in other models of similar vintage.

73,
Carl - wk3c

Carl,

Those same lamps will work in most Yaesu rotator controllers, though
in that case you need to add a 33 ohm resistor in series. The
controllers usually supply ~14 volts, and the resistor puts them
exactly on spec. Most people use the new LEDs with appropriate
resistor though. Runs cooler, and lasts ~forever.

Alan
WA4SCA

Carl,

Those same lamps will work in most Yaesu rotator controllers, though
in that case you need to add a 33 ohm resistor in series. The
controllers usually supply ~14 volts, and the resistor puts them
exactly on spec. Most people use the new LEDs with appropriate
resistor though. Runs cooler, and lasts ~forever.

Alan
WA4SCA

"Carl R. Stevenson" wrote in message
...
My Yaesu FT-4700RH had 4 "grain of wheat" style lamps
to provide panel/display backlighting. 3 of them had burned
out. These lamps are accessible from the back of the removable
control head. They are covered with pliable orange plastic covers
and inserted through holes in the PCB from the back side, with the
two leads bent over and soldered to pads on the back side of
the PCB, so they are easy to remove. (Save the orange plastic
covers to use on the replacement bulbs.)

I would suggest replacing them with LED's instead, then it is a one time
fix..

Robin

"Carl R. Stevenson" wrote in message
...
My Yaesu FT-4700RH had 4 "grain of wheat" style lamps
to provide panel/display backlighting. 3 of them had burned
out. These lamps are accessible from the back of the removable
control head. They are covered with pliable orange plastic covers
and inserted through holes in the PCB from the back side, with the
two leads bent over and soldered to pads on the back side of
the PCB, so they are easy to remove. (Save the orange plastic
covers to use on the replacement bulbs.)

I would suggest replacing them with LED's instead, then it is a one time
fix..

Robin