--------------------------------------------------
From: "Col. Paul E. Cater" <paulecater@gmail.com>
Sent: Saturday, January 24, 2015 11:57 AM
Cc: "Amps reflector" <amps@contesting.com>
Subject: Re: [Amps] ceramic vs glass
I didn't mention any numbers. If I did I would have pulled them out my
butt like most do.
** Unfortunately that is true.
I really don't know where you would find any reliable
data on it other then peoples experience and hearsay.
** Myself and several others across the many forums have decades of amp
experirence repairing them for others or replying to posts. I feel I can
trust the others and Ive kept pretty good records since the 60's.
Duty cycle plays the
most important role in all of this.
** That is the least important as the majority are on SSB and CW is a
distant second. RTTY is way down on the curve plus amp manuals specify the
derating for it and AM. Most digital mode users are proud of doing it with
100W or less.
My sole point was, tubes properly cooled last way longer in full tilt
buggy
then those that are not. The muffin fan jobs you mention and specifically
the SBs are not rated anywhere near the tubes capability. Niether is the
P/S for that matter.
Even contesting isnt full tilt use of an amp and there are still many
flogging a SB-220 which was built as a 1000W CW 2000W PEP INPUT amp. Maybe
you werent playing ham back in those days.
Having used both types at many MARS stations and myself, we opted for
something that used chimneys as we did not have to replace the tubes.
More
money initially but not popping bottles in and out. I was sitting here
trying to recall if I ever replaced a 500z in a top end amp, ie Henry. or
whomever. I do recall putting them in muffin fan decks often.
MARS isnt ham radio
Nope, didn't look up the spec sheet. Last time I looked at one cooling
was
stated verses usage with minimums. I'll have a look.
So, my opinion and experience speaking and nothing else.
** That is obvious.
Paul
WD8OSU
** So what about the Kentucky Colonel type of honorific? Id expect a real
USA, USAF, or USMC Colonel or other officer would
be a bit upset to see it always in their face. Im just a retired USN WO4 and
don't have to keep pushing it.
Carl
KM1H
On Sat, Jan 24, 2015 at 11:19 AM, Carl <km1h@jeremy.qozzy.com> wrote:
I don't know where you get those numbers from but they are obviously
improperly weighted.
First of all the 3-500 fan amps far outnumber the ones with chimneys by
a
huge amount,
the SB-220/221/HL-2200 alone sold in the 30-50K range according to many.
Fan failures are actually very few if the owners had enough smarts to oil
the bearings and remove the filth off the blades once in awhile. For an
amp
that first sold in 1970 it has an extremely good track record
considering the abuse it gets by clueless hams.
Reports of SB-220's with filament pin solder melting can always be traced
to builder inability to read and follow directions,
or a later owner being lazy or forgetful.
The positioning of the fan blade on the shaft is critical; plus that
little aluminum top piece is critical to direct air below the
chassis....many left it off after servicing the amp. A couple of other
brands were designed by those who didn't understand air flow and created
air dams below the chassis; drilling a few 1/4" holes at the end to
equalize release solved that problem.
The Command Technologies amps are another case of an air dam frying
components; this time the PS board and components.
The AL-80 family is also a huge 3-500 seller going back 30 years and fans
arent a problem for most even at the ridiculous power the manual says is
OK. Tubes and RF components fail but not due to the fan. When
manufacturers
switch to a cheap plastic fan to save money you can expect noise and
quality problems.
The Ameritrons with blowers and chimneys have their share of blower
failures or just noisy bearings that owners tolerate; the sales totals
are
actually quite low so you hear little about it but there are far more
active amp forums than this very obsolete email reflector.
Something else you obviously missed is that Eimac approved in writing and
later in spec sheets the use of fan cooling as far back as the 60's for
the
Johnson Thunderbolt which used 4-400A's. The stipulation was that seal
temperatures not be exceeded and Im not
aware of any 4-400, 3-400, or 3-500 that had a glass meltdown in normal
use....CB use doesn't count!
Carl
KM1H
--------------------------------------------------
From: "Col. Paul E. Cater" <paulecater@gmail.com>
Sent: Saturday, January 24, 2015 9:40 AM
Cc: "Amps reflector" <amps@contesting.com>
Subject: Re: [Amps] ceramic vs glass
I'm dubious about some of the ceramics. The ones that require more parts
to
protect it then actually use it and the old Russian jobs.
The 500Z is a time proven design. Many of the failures are do to
mechanical issues, over optimistic ops, and not the tube itself. I have
never understood why someone would build up a pair of 500s and put a
muffin
fan on them. Cheap commercial jobs do this to save money. It is really a
disservice to the tube and it's capabilities. The mean time between
failures on muffin fan types and actual blowers with chimneys on these
guys
is enormous.
Paul
WD8OSU
On Sat, Jan 24, 2015 at 9:08 AM, Jim Thomson <jim.thom@telus.net> wrote:
Date: Sat, 24 Jan 2015 12:53:21 +1030
From: "Leigh Turner" <invertech@frontierisp.net.au>
To: "'Bill Turner'" <dezrat@outlook.com>, <amps@contesting.com>
Subject: Re: [Amps] 5 Minutes for Ameritron 811H to warm up?
Personally I wholeheartedly concur with your sentiments here Bill; most
of
my shack amps are of the ceramic tube variety and indeed do seem to
last
forever.
My only exception amp is the venerable Kenwood TL-922 with its
nostalgic
pair of Eimac 3-500Z glass bottles...they too have proven very reliable
workhorses! The proviso rider with any tube is absence of abuse.
73
Leigh
VK5KLT
## whats the most anybody has gotten out of these russian ceramic
wonder
tubes
like GU-74B etc ?? Can you get 20 years out of them, beating on em
7
days a week,
like an Eimac 3-500Z ?
## What is longest anybody has gotten out of an Eimac 8877 ??
## at least with the bigger eimac ceramic tubes, like 3x3, 3x6, 3x10,
4x5, 4x10,
they can be re-built till hell freezes over, unlike their throw away,
smaller ceramic
siblings. IMO, you get a bigger bang for the $ with the bigger
ceramic
tubes, esp
since being thoriated tungsten fil, you can reduce the fil V way down,
like 12% or more,
further extending tube life. Take a 3x3... rated for 2.5 A CCS plate
current...then run it
at 1.5 to 1.7 A plate current..alon with reduced fil V. It will last
forever.
The typ 2 x 3-500Z amp is rated at 800ma max plate current.... and my
L4B
runs
at 800ma..just to get 1290w po.
Jim VE7RF
_______________________________________________
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: 2015.0.5645 / Virus Database: 4273/8987 - Release Date:
01/24/15
_______________________________________________
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: 2015.0.5645 / Virus Database: 4273/8987 - Release Date: 01/24/15
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|