Yes. That's correct.
I use a cheap plastic tub with a filament transformer and small blower
from an old microwave oven mounted inside. The tub is inverted and the
base of the tub has the tube socket and tube mounted on it.
The lid of the tub forms the base. I can lift the tub off the base and
shoot up inside, at the bottom of the tube, with a infra red thermometer
(cheap Chinese copy of a Fluke, that is surprisingly accurate) to keep a
check on the temperature/s.
I have found that this set up is sufficient, even for tubes as large as
the YC156.
I did GU74Bs, FU728Fs, GU84Bs and YC156s. I just changed out the
filament transformer each time and enlarged the hole to accommodate the
larger socket for each tube type. When the dozen or so tubes were all
done, the plastic tub was thrown in the recycle garbage bin.
The next time I did it, I bought another tub and did the same thing,
progressing from the smallest to the largest tube sockets. It takes less
than 10 minutes to chnge to a different tube type.
73, Alek
VK6APK
On 29/11/2014 12:39 AM, Carl wrote:
A small fan is fine.
Carl
KM1H
----- Original Message ----- From: "Pete N4KW" <n4kwpete@centurylink.net>
To: <amps@contesting.com>
Sent: Friday, November 28, 2014 10:43 AM
Subject: Re: [Amps] Holding a vacuum
Earlier this week I emailed Eimac with the question about shelf life
of the new 4CX1500B tubes that I have. I also asked about the serial
number on the tubes and how to read it.
I am awaiting the code for the serial number, regarding shelf life
they recommended that I at least apply filament voltage every six
months. If one was to apply filament voltage would a blower be
required or not for this tube.
73 Pete N4KW
On 11/27/2014 3:24 PM, Carl wrote:
----- Original Message ----- From: "Bill Turner" <dezrat@outlook.com>
To: "Amps group" <amps@contesting.com>
Sent: Wednesday, November 26, 2014 11:08 AM
Subject: [Amps] Holding a vacuum
I'm curious as to your experiences with tubes in long term storage.
The question is, which type holds a vacuum better - glass or ceramic,
or is there no difference?
My own limited experience says ceramic is better, but that is only
with a few tubes.
All comments welcome.
73, Bill W6WRT
"It all depends" as they say.
Some ceramic/metal and glass/metal are notorious leakers such as the
4CX300A and PL-172 and PL-172A. Popular ones such as the 4CX150A
family, 8874 family, 8877, 3CX3000A, 4CX1000A/1500B hold vacuum well
but the indirect heated types such as the ones above (not the 3X3)
should be run up to 24 hours with just filaments to regetter from
outgassing. This includes the 8072/8121/8122 and long stored Russian.
Eimac had a couple of bad years in the late 80's with the 3-500Z
when they moved the plant to SLC; other than that they just had
outgassing as did most glass tube and need regular running with
color to regetter.
The 3-1000Z and 4-1000A often went to air as well as did many of the
larger WW2 tubes such as 450/750 TH/TL, 6C21, and larger.
OTOH I have a pair of 1934-35 HK-354's that still run at a KW on AM
but other 20's to 30's TX tubes are almost impossible to find
(mostly RCA) with seals intact; 203A, 204A, 211, 849, 851, 852, and
others.
Ive little to no experience with Russian and non US clone Chinese
tubes but have heard a lot of good things about Chinese
military/broadcasting ones in particular.
Carl
KM1H
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.5577 / Virus Database: 4223/8645 - Release Date:
11/28/14
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
--
http://www.qrz.com/db/vk6apk
http://www.qrz.com/db/vk6ap
Family Businesses:
SP Electrical. www.spelectrical.net.au
Hampers by Hand. www.facebook.com/hampersbyhand
---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|