[Mldxcc] [NCCC] RTTY & 3-500Z amplifiers

[Jim Venneman]

Hi Rick,

I also have a Model 422 Centurian which I used in the recent ARRL RTTY Roundup. I've only owned it for a short time and this was also my first RTTY contest. So - I ran mine at 500 watts out for the entire contest and the amp handled this just fine. Even though the amp is rated at 650 watts out for RTTY, I decided to err on the conservative side. I noticed that the tubes reached a dull red glow now and then, but nothing worrisome. I also had a desk fan blowing across the back of my operating desk positioned in such a way that it blew air across the back of my IC-765 and also into the ventilation slots on the side of the amp. With 500 watts out, I had plenty of activity, made lots of contacts, and worked everyone that I could hear.

I gather that you are preparing for the CQ WPX RTTY contest coming up shortly. If so - I'll see ya on the bands!

Jim  -WX6V-




________________________________
From: "Rick, W6RKC" <ab1u at volcano.net>
To: mldxcc at contesting.com; nccc reflector <nccc at contesting.com>
Sent: Monday, February 2, 2009 7:59:53 PM
Subject: [NCCC] RTTY & 3-500Z amplifiers


Hello all,

after 10 years, I finally got the OK from the XYL to move "SOME" 
radios into a now spare, empty nest syndrome, bedroom. I wired up a 
couple of 20A 110VAC circuit breakers and got on the air last fall. 
Finally got around to wiring up a 30A 220VAC line for an amplifier. 
Since it will work on 160 thru 10 , including WARC, I hooked up my 
Ten-Tec Centurion Model 422  which uses a pair of 3-500Z tubes.

It works fine on CW & SSB and I have used it on RTTY for the first 
time in ARRL RU. I set the drive level to give about 700 Watts out 
when using RTTY. It is also located in a spot where I am now able to 
see the tubes. I have noticed that the plates will glow when using 
RTTY. My question is, should I see a dull reddish tint, the color of 
a Naval Orange or the color one might see when observing the core of the Sun?

As I currently cannot afford to purchase another pair of tubes, I do 
not want to damage these. They will do 1200+ watts out on CW or SSB 
with a nice dull glow, I can however, read a book when doing RTTY as 
they approach sunlight level. There is no external cooling applied 
right now. Just this weekend, I went through a junk box in the garage 
and found a nice DC muffin fan that I will be wiring up. My previous 
attempts at RTTY were with an Alpha 76A. With the ceramic tubes and 
metal cover, it was a case of "what you don't know, won't hurt you" 
when using the Alpha.

Since the 17 & 12 meter WARC bands will not be viable for a while 
yet, maybe I will just swap it with one of the Alphas.

Does anyone have any comment on 3-500 plate color and RTTY operation??????

Thanks & KB

Rick, W6RKC

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