[BC] Re: 5CX1500

[Xmitters@aol.com]

In a message dated 5/18/05 12:01:27 AM Central Daylight Time, 
broadcast-request at radiolists.net writes:

<< Milton 
 
 I agree with you.  Most of the 5CX1500 A users would have been better off 
 with the 4CX250B driving a 3CX1500 triode. or maybe a 3CX3000.  The tube was 
 really squirrley and required too much serious tweeking for Class A 
operation.
 
 The first reasonable tube was the 4CX3500,  which they had a lot of seal 
 problems with for a while.
 
 Dave >>


Dave:

I had an FM-2.5H3 and FM-2.5K (Harris) Both ran at 2350 watts. I never had 
any reliability or performance issues with either transmitter. The 2.5H3 was my 
original main and was replaced by the 2.5K. The 2.5K ran for two years on its 
original tube.

During this time period, Eimac had an issue with the ceramic insulators on 
the tube body and suggested that stations decrease their Ep and tune up with 
more plate current to compensate. My tube replacement cycles apparently "bridged" 
this time period and consequently, I never had any tube issues. We would 
replace the tube every year, year and a half or so, but never had a transmitter 
outage due to a failed tube. The reason the 2.5K ran for two years is, the young 
fellow that replaced me did not want to dig into a working transmitter :-) He 
only did so once the tube aged to where it would not make power.

Now, I did have a rebuilt that was dead on arrival a couple of times. That 
was no problem however for Econco's top shelf, unbeatable warranty policy :-) 
Our policy was to watch the transmitter parameters like a hawk, keep the 
transmitter PA spotlessly clean, and check/replace any questionable finger stock on 
the plate line.

So based on my experience, I have no problem with the 5CX1500. This 
experience goes back several years and maybe this tube is not this good anymore.

Jeff Glass, BSEE CSRE
Chief Engineer
WNIU WNIJ