David,
We used to use a product we called Templaq or Templac in the military. I
did a quick Google search and found the following pdf file - it has three
manufacturers of temperature sensing paint listed in the body of the
document:
http://www.hill.af.mil/scsweb/pdl/pubs/li210102.pdf
I hope this helps. You should be able to determine your maximum device
temperature, which should put your mind at ease. Another, major exotic,
method would be to put an infrared sensor (el-cheapo radio shack IR
transistor) into a hole in the wall of the cavity (pointed at the anode) and
meter it. Lots of cut and try involved; however, you would be able to
monitor temperature during use.
73' de Dan/KB4L
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
Behalf Of David and Wendy Dodds
Sent: Sunday, February 09, 2003 7:02 AM
To: amps
Subject: [Amps] cavity temperature
Hi all.
I'm almost finished putting together a 23cm cavity amp - just a single 7289
round cavity, similar to N6CA's design.
My concern is cooling. I'm using forced-air cooling, which seems pretty
effective in that the exhaust air never gets dramatically hot, even when
running cw for a protracted period of time. What does get hot is the anode
tuning control, presumably due to convection along the shaft (which is only
1.5 inches long) The Eimac spec sheet for the 7289 shows a safe maximum
operating temp of 250 degrees celsius, so I guess it's ok for the cavity to
be pretty hot!
Should I be worried that this is an indication that the cooling isn't
sufficiently effective or am I worrying too much?
I haven't come up with a safe (and cheap!) way of measuring the temperature
of the anode fins. I could probably get to them down the exhaust chimney,
but as they are at 1100v I don't fancy poking a thermometer down it (even if
I had one that went up to 250 deg!)
Any ideas, thoughts, suggestions?
Tnx es 73
de David GM4WLL
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
To: <amps@contesting.com>
Version: 6.0.443 / Virus Database: 248 - Release Date: 11/01/03
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|