[R-390] LED lamp replacement

[Don and Diana Cunningham]

The truly nice thing about LED's is that you don't have to convert AC to DC
to run them (or am I missing something, after all, they ARE diodes????).
73 all,
Don, WB5HAK (lurker)
----- Original Message -----
From: "Bob Camp" <ham at cq.nu>
To: "Tom Norris" <r390a at bellsouth.net>
Cc: <R-390 at mailman.qth.net>
Sent: Tuesday, July 06, 2004 9:49 AM
Subject: Re: [R-390] LED lamp replacement


> 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
>
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