Hi folks,
Ater receiving a couple requests for the specifics of the LEDs I use in the
K2 (K1, KX1) keycaps, I thought I should share this with the entire Elecraft
world:
The ones I found that work were in the Digi-Key catalog and are manufactured
by Aligent Technologies.
Green - DigiKey 516-1405-ND - Mfg. # HLMP-6500
Red - DigiKey 516-1398-ND - Mfg. # HLMP-6300
To install, drill a small hole into the center of the keycap (ream it to
size with a knife blade if necesary), and cut the inside plastic of the
keycap to the bottom to accomodate the leads as described in Jerry Henshaw's
description. Cut the LED leads to a reasonable length and solder wires to
the these leads then put the keycap back in place over the switch - be
certain the drilled (and reamed) hole is just large enough to insert the LED
so it barely projects out the front of the keycap, and at the same time,
small enough to grip the LED body a bit so it is a snug fit.
These LEDs do take a bit more current to bring up a reasonable brightness
than I would like to have, but not so much as to be a problem. With the
N0SS tuning indicator, I successfully used a 1.5k series resistor (power is
taken from the 5 volt supply and the open collector driver provides the path
to ground), and the brightness was dim but adequate. I haven't measured the
actual current with the tuning indicator, but I guess it is in the
neighborhood of 2 ma. The forward voltage I measured on one LED is 1.74
volts, and the manufacturer's data sheet says they are good up to 30 ma., so
greater brightness could easily be achieved with a lower value resistor -
chose your resistor and take your pick.
73,
Don W3FPR
-----Original Message-----
>
> In the K2, the tuning indicator is usually installed such that it will
> blink the 10th LED of the S-meter LED to indicate when you're
> tuned to the
> other guy's signal. Don Wilhelm, W3FPR, tells me he prefers to use a
> separate LED for this purpose, and he mounts a mini-LED inside the K2s
> [LOCK] button. Of course you, the builder, can choose how you wish to
> implement the LED indicator.
Folks,
Not quite true - I put the tiny LED in the SPOT button, I figure its
function is more intuitive in that position. If you want to know how to put
the LED in the button keycap, get Jerry Henshaw's original info from Tom's
website
http://www.n0ss.net/kr5l_led_cw_tuning_ind.pdf, which will tell you
how to mount it in the LOCK/RATE button - it fits in the SPOT button in a
similar manner, and could also be used for the buttons of the K1 and KX1 if
you don't want to drill a hole in the case. Restoring to original
appearance is a simple matter of replacing the keycap.
73,
Don W3FPR
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