Picked up from the usual auction site on 16/1/22 for £19.70. At the time I was (and still am) contemplating and planning for some portable operations one day - and this key looked like it could be a great candidate - small, rugged, dust sealed.
There doesn’t seem to be a huge amount of information on these keys out there on the internet. They do seem to come under a few different names from a few different manufacturers, such as the ‘BCE 502’, C307 as well as McMurdo 1002.
My key seems slightly unusual in that it has a longer metal base with an extra ‘tx/rx’ switch attached. This does very much look like an original part, but most of the pictures on the internet don’t have this.
Reading around, this key looks like it was combined with Racal radio sets, and is designed as dust and waterproof, and was even used on liferafts?
The key came pretty clean. Well, hopefully being water and dust proof, you’d sort of hope that had done its job. The cable into the switch though was not sealed, so there goes the proofing for the rx/tx switch. As usual, I tested the key with the multimeter - hmm, a dead short. Not a great start. So, now, how do we take apart a sealed key? At first I tried to get in via the top of the key, but that only got me so far (see later). After unmounting the key from the wooden base and flipping it over, there were a few screws looking promising. After removing the screws it became apparent that the rubber gasket was partly welded to the case. That may be by design, or it might just be through age. With some very gentle prying (I didn’t want to have to re-make the gasket later if necessary), I got it apart. Voila!, we can now see inside both the switch and the key.
Hmm, now, let me see - can we see anything obvious that might be causing that short!!
Out with the soldering iron and on with the re-wiring… that’s better, now the key is functional!
The key came with quite a long and stiff stroke. Some of the internet references say this key is not adjustable. Well, that is true from an external daily point of view. But, what about inside the key? Here we go again then - this time we really need to get the top open. Now we understand that the gaskets have welded themselves on, we can be a little braver…
There is a strange arrangement with an extra little plastic ‘spacer’ on the front of the key. Also, note, there are different length screws. It is not too hard to figure out which go where on re-assembly, but taking digital photos during disassembly is a cheap backup when disassembling things…
Now, if we gently prise around that upper gasket, finally we get inside… note, in this picture I have re-attached the knob so I can adjust tension and gap. Also note the interesting rubber gasket that sits around the knob post - we’ll get to that in a moment.
Now we can see there are two adjusters - a smaller one at the front with a nut on a post, and a larger screw post at the back with a locking nut. Frustratingly, I have forgotten which one is the gap and which is the tension, and I can find no notes on it! But, rest assured, they are gap and tension adjusters, and I did adjust my key.
Now, a word of caution - you need to adjust the key when it is open, but once you put it back together that little rubber seal that sits around the knob stem adds some more stiffness to the key! So, you may wish to adjust the key to be a fraction soft on the grounds that the grommet will stiffen it up a little when you re-assemble it. A pain I know, but as far as I can tell, unavoidable.
I’ve not taken this key on the air yet!, and I probably need to open it up again and make further adjustments to cater for that rubber seal. My key is still currently a little stiff, and has a very short travel. The stiffness may always be present due to the seal. As a tiny potentially POTA or SOTA key, I think it has great potential - tiny, dust and waterproof! The key is pretty quiet to operate, being completely contained, but is still slightly louder than I though - I have a feeling it is currently resonating through the wooden base!