Collins KWM-2A

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wsykes41770

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I recently acquired a Collins KWM-2A rig. I want to put this rig on air and use it, but as I've never used one before, I was wondering what I need to look for and/or replace before I fire this rig up for the 1st time. I would hate to power it up and start using it only to cause some problems that might have been prevented in the first place. Thanks.

Wayne
 

prcguy

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Do you have a power supply for it? If so the power socket on these are notorious for breaking the key so make sure the multi pin plug is orientated correctly befor powering up. I would also use a variac and bring it up slowly to make sure nothing is shorted and it's kinder to the filter caps. I would also recommend downloading the manual and follow the transmit tune up procedures. Otherwise the KWM2A is a fun radio to operate.
prcguy



I recently acquired a Collins KWM-2A rig. I want to put this rig on air and use it, but as I've never used one before, I was wondering what I need to look for and/or replace before I fire this rig up for the 1st time. I would hate to power it up and start using it only to cause some problems that might have been prevented in the first place. Thanks.

Wayne
 

wsykes41770

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Mount Juliet, TN
Thanks. Yes, I have the original power supply along with a bunch of the accessories. It came with the phone patch box, speaker, and watt meter. It belonged to an organization that I am a member of and they were just going to throw it out. I jumped on it and took it home. They said it was working when they stopped using it years ago.
 

W2PMX

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If it's been sitting unpowered for years, I'd first open both the rig and the power supply and clean them out. You might find insects, spider webs, dust - lots of things that can cause shorts and even fires. (Remember, this is tube equipment, so it's running on high voltages, not 12 volts.)

The second thing I'd do is check the electrolytics. Or, if you can afford it, just replace them all. If not, I wouldn't use a variac - you'll be running high voltage (not full, but high) on the plates and screens while the filaments will be underpowered - an easy way to destroy tubes. You could use a variac on the power supply alone - with a dummy load (a high-powered resistor) on the high DC voltages to keep things safe. But I wouldn't do that with the KWM2 itself connected. Unless you like fireworks in a box.
 

W2NJS

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As you go through the preliminary steps, start shopping for a good source of tubes as you will some new ones now or not too far in the future. Also, check the crystal board to see if there are any extra band segments included in your radio. I believe that the "A" model had provisions for a user to expand the coverage of the radio. At point many owners added a Waters rejection filter to their M2s and your radio may have this desirable addition installed already. Also, there is a Collins users group on the Web where you can learn a lot more about these great radios.
 

prcguy

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None of the tubes used in the KWM2A will be damaged even the slightest by running for a few minutes at low filament and high voltage by slowly turning up with a variac. My variac has voltage and current meters which is a great tool for spotting problems while the HV is ramped up.
prcguy


If it's been sitting unpowered for years, I'd first open both the rig and the power supply and clean them out. You might find insects, spider webs, dust - lots of things that can cause shorts and even fires. (Remember, this is tube equipment, so it's running on high voltages, not 12 volts.)

The second thing I'd do is check the electrolytics. Or, if you can afford it, just replace them all. If not, I wouldn't use a variac - you'll be running high voltage (not full, but high) on the plates and screens while the filaments will be underpowered - an easy way to destroy tubes. You could use a variac on the power supply alone - with a dummy load (a high-powered resistor) on the high DC voltages to keep things safe. But I wouldn't do that with the KWM2 itself connected. Unless you like fireworks in a box.
 

wsykes41770

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Oct 18, 2011
Messages
90
Location
Mount Juliet, TN
Thanks for all the great hints and tips guys. I already cleaned all the dust and cobwebs out the day I got it, so that is already done. I still have to get an antenna up before I can proceed any further and it looks as if that will have to wait until after the holidays. You know how busy it gets this time of year!!
 

W2PMX

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I still have to get an antenna up before I can proceed any further
Save yourself and everyone else problems, and do your preliminary testing on a dummy load. Once you know that the transmitter works, and the signal is fairly clean, you can connect an antenna.
 
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