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CCA AM1000D transmitter

I removed a CCA 5000D transmitter a few years ago. Count on one of these making a lot of heat, and eating up tubes. Not a good radio at all.
 
Nothing special, it's basic 4-400 rig of the day. Paralell class C final modulated by push pull pair. Peak the grid on the finals, dip the plate and load it up. You should end up with around 3100 volts at around 450 ma on the final amp for a 1kw out. One thing you might check is the filament voltage on the 4-400's at the socket. Should be 5 volts, if it's substancially higher you will eat tubes fairly quick. I have found that the graphite plate Amperex made in France hold up the best in my RCA"s. I get about 18 to 24 months out of a set running a KW 24/7. Those things are getting pretty salty at over $300 a tube!
Good luck with the rig.
 
I have three of these transmitters still in service and on the air everyday. Like Vacuum Tube said, Use the Amperex graphite plate tubes if you can, I have had the best luck with them. I had bad results with the cheap Chinase and Russian tubes. And as Radionekkid said, tune the plate tuning about 40 to 50 ma off of the dip. On one side of the dip, plate current will rise and power will drop and on the other side current and power will rise. Other than tubes the only problem I have had with the three that I maintain is the 1 Meg resistors in the back of the PA compartment. These are in the feedback network for the Modulator section. I have had to replace these resistors twice in all three transmitters. Normally I get about 18 months on a set of tubes. This thing is 30+ years old but given the luck I have had with these three I think it is still a great transmitter.
 
WZHR in Zephryhills, FL runs one of these. The power supply is quite a jury rig. When I first saw this gem, the modulation transformer was sitting on a piece of wood because of a short to the core. The owner was too cheap to replace it until it died entirely. The transmitter is in a 6 x 4 shed in a cow pasture. A window shaker runs 24/7
 
druidhillsradio said:
When I first saw this gem, the modulation transformer was sitting on a piece of wood because of a short to the core. The owner was too cheap to replace it until it died entirely.
Click to expand...

This is not an uncommon practice, and frankly I agree with the owner.... I wouldn't have replaced it either. They usually will run for years and years as long as you isolate them from the cabinet. This usually happens with the HV transformer though.

Don't knock the CCA -- it's a great rig.... and I'd be willing to bet that there are probably still dozens of them in service as primary transmitters, and hundreds in standby.
 
druidhillsradio said:
WZHR in Zephryhills, FL runs one of these. The power supply is quite a jury rig. When I first saw this gem, the modulation transformer was sitting on a piece of wood because of a short to the core. The owner was too cheap to replace it until it died entirely. The transmitter is in a 6 x 4 shed in a cow pasture. A window shaker runs 24/7
Click to expand...

Many times, this measure of isolating the core from the chassis was preemptive rather than after the fact.
 
Timed out on me:

Also be aware of the deterioration of the carbon composition resistors used throughout. Since most of these lived in widely varying seasonal climates, heat will take a toll on them over time and cause important bias, feedback as well as other parameters to change; adversely affecting the quality. Carbon resistors exhibit a negative temperature coefficient, meaning the resistance decreases with increased heat. I would take an ohmmeter to every one of them.
 
Other than a tube going bad about the only problem I can remember having with this transmitter has been the ten or twelve 1 meg resistors in the feedback circuit of the modulator stage. I use the metal film resistors as replacements and havent had any more problems from them.
 
druidhillsradio said:
WZHR in Zephryhills, FL runs one of these. The power supply is quite a jury rig. When I first saw this gem, the modulation transformer was sitting on a piece of wood because of a short to the core. The owner was too cheap to replace it until it died entirely. The transmitter is in a 6 x 4 shed in a cow pasture. A window shaker runs 24/7
Click to expand...

My parents winter home is about a half mile from where I thought that tower was. I noticed this year the tower was gone. Did they move it down to Dade City with the other station? I thought that is was about a half mile past wal-mart going toward Dade City on the same side of the road.
 
I have a CCA FM20000 made in 1971 (been taking care of it since 1981)...it has a 2x6 under the shorted filter choke, it's the only transmitter for the #1 station in the market. Would the owner buy a new transmitter if I asked? Probably...but the CCA 20 running at 7KW with only 4800 volts on the plate just runs...it never arcs or does anything weird. Give it a good bath once a year, keep a clean air filter on it & feed it a 5CX1500B every 18-24 months & a 3CX10000A7 every 3-4 years & it's happy to be of service. It would be hard to find a transmitter more reliable than this 'ole CCA at any price. Hopefully the AM1000D is as reliable. I cut my teeth on a new CCA in 1967 & remain a big fan of their simple, straightforward method of generating lots of RF with very few parts.
 
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