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Re: [Amps] 813 efficiency

To: <amps@contesting.com>, "Bill Fuqua" <wlfuqu00@uky.edu>
Subject: Re: [Amps] 813 efficiency
From: "Carl" <km1h@jeremy.mv.com>
Date: Tue, 26 Feb 2013 14:29:32 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
The 4E27A seems to be an audiophool contender and getting pricey plus it is a HV, low current tube to be efficient.

Eimac uses the first character to signal number of elements starting after WW2.

Another sleeper is the PL-175, very few realize it is a plug in swap with a 4-400A, and is often almost given away. I picked up a pair NIB on Fleabay for $25 not long ago. I added a NIB Eimac 175A to the TX tube collection for $10.

I also picked up a pair of NIB QB5/1750's from the same place for $20, those will be modulating a NOS 4PR1000A.

There are also several other seldom heard of NIB TX tubes in the collection that are simply a standard tube with a funny ID on it (-;

Carl
KM1H



----- Original Message ----- From: "Bill Fuqua" <wlfuqu00@uky.edu>
To: <amps@contesting.com>
Sent: Monday, February 25, 2013 1:22 PM
Subject: Re: [Amps] 813 efficiency


One tube in the 813 class never mentioned that is real cheap because practically very few
amplifiers or transmitters used them is the 4E27A Pentode.
It has 125 watts plate dissipation and fits into a 813 socket.
Anyone out there use one in grounded grid operation? Should be similar to
813's I would guess.

It just dawned on me the designation used in that tube series.

3B28 is a diode
2C40 is a triode
4D32 is tetrode
4E27A is pentode
the letter is describes how many element it has Obviously there is not an
A designation.
Wonder who came up with that one. Don't see a pattern for the numbers.

73
Bill wa4lav


At 11:09 AM 2/23/2013 -0500, Carl wrote:
For about the same money there are still many 4-250A and 400A's available.

Carl
KM1H



Hi Guys,

It absolutely gobsmacks me how some guys in this hobby would rather whip-out the ol' VISA card & spend literally HUNDREDS on power amplifier tubes, when the lowly ol' 813---paired with some twins, of course!---will do the job as well, and at an absolute FRACTION of the price...

Sure the tube has high interelectrode capacitance, & has been around since before WW2: but so what? It's nothing that a bit of 21st century technology can't master...and who cares about age? After all, I myself am 60 years old here, & hardly consider my existence to be "redundant"! Hi Hi

~73~ de Eddy VE3CUI - VE3XZ
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