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Anybody still run Mc Martin Transmitters?

R

RF Man

Does anyone out there still run McMartin? I have one that has control problems and would appreciate any help. This one is a 3.5K and keeps blowing the control board fuse which is rated at 5 amps. Larger fuse does not blow. Getting no plate off light and have checked all interlock switches.


Thank You
 
They built absolutely the best SCA receivers of anybody. And, whether their RF stuff is good or not, the gent is looking for help, not our opinion of the quality (Which we share on transmitters).
 
We have an ancient McMartin 3.5 that we upgraded to a 5 KW at one of our sites and it gives us a lot less grief than many of its newer solid state bretheren. Despite numerous lightning storms, power failures and a transmitter shack (literally) with no AC, it just keeps cranking out the signal.
 
I had a McMartin 3.5 many years ago and can recall this circuit being one of the weak points. Seems like I remember having problems with the relay sockets soldered connections as well as the previously mentioned problem with bad relay drivers.

The blown fuse is a bit of a puzzler. Install the correct size fuse, disconnect the output of the control voltage power supply and fire it up. This will at least tell you if you have a problem with the supply or the load.
 
Pull the circuit board off the wall of the transmitter. pull it awy from the pvc holder. Look at the back of the board for a blown trace which is a result of lightning.

Get some solder wick, solder it up, and use it to replace the large trace that vaporized.

Install a grounding strap on the cable outside the building to the tower leg and to ground.

Place mov's or lightning protection on the incoming ac.

I have a 10kw McMartin I would be using but don't want the rotophase bill and don't have 3 phase. It is available.

Solid boxes. Charlie has been great on parts.
 
Wasn't the CCA offered as a 10 single phase? I bet you could use the same components for a McMartian and it would do as well. Seems like CSI single phased their bigger onews as well.
 
littlejohn said:
Wasn't the CCA offered as a 10 single phase? I bet you could use the same components for a McMartian and it would do as well. Seems like CSI single phased their bigger onews as well.
Click to expand...

I did try to get a schematic from CCA for a 10 single phase. Anybody have one? Feel free to email me.

The control ladder is also 3 phase. Copying Continental? That should be easy to fix however. Worried about Am noise if I set the Plate Supply incorrectly.

I could sell my hardly used Arko rotophase.

Also looking for a source for silicon rectifiers for hv use. 10kv up at 2 amps up.

harris has them but can't pay that price.
 
Thanks again. I have a reasonably priced schematic on the way along with a few extra parts I ahve been needing to order.
 
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