[BC] Are there AM stations still using Tube Rigs?

[wmroradio at bellsouth.net]

Jeff & Others whom have made comments:

    We have rebuilt our antenna system with better, stronger, wire for the folded unipole, but the ATU has to be rebuilt. New components are going in and we are going back with the standard "T" Network.

    If we run into problems with the ATU, I'll just break down and buy the matching network for the BE. I hate the idea of a tube transmittter. I miss changing the tubes and tune up, but not the heat and the AC bill!

    Thanks all for the advice!

Scott

--
Scott Bailey
President/General Manager
WMRO-AM, Magic 1560
Gallatin, TN

  
> Scott:
> 
> I'm sure there are many stations using tube transmitters. One station I know, 
> a 5 kW directional, uses a Collins 820E, which uses two 4C5000A in a  class B 
> modulator and 1 4CX5000A in the PA; conventional plate modulation. Since that 
> rig was installed in 1972, I can count the number of failures on one hand, 
> and still have fingers left over :-)  The same station uses a 20V3 at night, 
> with a similar outstanding track record.
> 
> I do have to disagree with you that a tube transmitter sounds warmer than SS. 
> There are many, many things that control the transmitted sound quality other 
> than the transmitter itself, like audio processing. I would use any 
> transmitter if I were allowed to use a patch cord for my audio processor :-)
> 
> Regarding your Z match issues, I kinda miss not having Tuning and Loading to 
> be perfectly honest. I think it would ultimately be to your best advantage to 
> optimize your matching network at the tower, find a phase shift that gives you 
> good impedance characteristics across your AM channel, and also present an 
> honest 50 Ohms to your BE transmitter. My experience has been that once all of 
> these things are set up initially, they do not need daily cranking to keep the 
> transmitter happy. 
> 
> If you have a wandering load Z on your transmitter, you need to find out why 
> it's wandering rather than buying a tube rig or BE's matching network. Getting 
> your system load Z stable will be cheaper in the long run. 
> 
> Honestly, I do miss the days of replacing tubes, optimizing the 
> tuning/loading so the modulator is happy, efficiency is good, plenty of TPO to 
> feed the 
> antenna or common point. I used to really look forward to doing that stuff :-)
> 
> If you have a system with a constant load, there's not much point to having 
> tuning and loading. Remember that SS is not forgiving like tubes. Tubes will 
> tolerate a short term piss-poor load that generates more heat than RF. 
> Transistors cannot tolerate that, whichis why I'm glad in a way  there's no 
> longer 
> tuning and loading. The BE 1 kW is a nice little transmitter. The ones near me 
> are 
> like Energizer Bunnies; they keep going and going, or whatever that 
> commercial says. You get my point :-)
> 
> Jeff Glass
> Northern Illinois University
> Dell 2650 Win2000 AOL 7.0
> 
> 
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