[R-390] LED lamp replacement

[Bob Camp]

Hi

Well I guess I run the risk of getting thrown off for mentioning this 
but the issue with the LED lamps is more or less the same as some of 
the solid state ballast replacements. (duck and run for cover ....).

When you convert AC to DC to run the LED's the current is only going to 
flow in short little pulses when the AC waveform is higher in voltage 
than the DC turn on point of the LED. The pulsing of the current 
creates noise clear up into RF. The R-390 was not designed to be 
shielded against this sort of thing going on inside the radio.

If you decide to go the LED lamp route I would suggest that a separate 
wire routing power for the LED's would be a good idea. Then come up 
with as quiet an AC to DC conversion as possible and stuff it off in 
the power supply module. At least that way it's as far from the IF and 
RF as possible. Just for the record, yes I stole that idea ....

The nice thing about the LED's is you can get an awful lot of light out 
of them these days. I have an R-1051 with an LED conversion in it that 
works very well.

The illumination angle coming out of an LED is more narrow than the 
angle of light coming out of the bulbs we normally use. One solution to 
this is to do violence to the front end of the LED. The other is to run 
multiple LED's. If you get your DC off of the 25 volt AC line then you 
can put quite a few LED's in series ....

Since the bulbs for the 390 are still commonly available and fairly 
cheap I'm not sure I would do all this work on a 390. If and when the 
bulbs get into the $40 a bulb category like the R1051 bulbs then we'll 
have a bulb replacement thread on here that goes on and on forever.

	Take Care!

		Bob Camp
		KB8TQ