[Amps] Questions about Amps/Tubes/Design

[jeremy-ca]

AL-82  Not a high volume seller since it was initially priced very close to 
the AL-1200. Also has a reputation of doing nasties due to the above average 
voltage used. Ive reoaired several that have since held together well.

Amp Supply. The LK-500 had several models and every model had its own 
production changes. Weak link is the bandswitch configuration that allows it 
to arc to the support hardware. Easy fix if you do it before it happens.
The LK-500ZC was the last and when equipped with the PD xfmr and vacuum 
relay it is hard to beat. Ive had one since new.
Stay away from the No Tune versions unless you can get dirt cheap and then 
redo as a tune type. They use the same variables as the SB-220, and many 
Dentrons so they are not scarce. I often convert the NT's to 6M monobanders.

China is the only source of new production 3-500Z's for now. Grab a pair of 
NOS Eimacs and use them once a year or so to keep fresh, the value will 
never go down. Otherwise use what you can get until the sources dry up.

Ive never used a ceramic Russian tube so cant comment. However there seems 
to be a readily available supply of near new Eimac 3CX800A7 and 8877 medical 
varieties at fair prices. Ive had no problem getting full power out of ones 
from honest people; they go into customer amps.

Carl
KM1H


----- Original Message ----- 
From: "Lee Buller" <k0wa at swbell.net>
To: <amps at contesting.com>
Sent: Saturday, March 15, 2008 11:46 AM
Subject: [Amps] Questions about Amps/Tubes/Design


>
>
> I am looking for a second amplifier.  I have some questions....
>
> 1.  Why are there very few AL-82 amps for sale on the used market?  Either 
> they are turkeys or great amps.  I think they might be a great amp.  2 x 
> 3-500Z is pretty simple.
>
> 2.  Amp Supply - are they any good and what is the pit falls with these 
> amps.  Seem to be straight forward design.
>
> 3.  I get a little concerned about amps that use "ceramic" tubes.  My 
> experience has been with "glass" tubes like the 3-500Z.  I get a little 
> concerned as to the availability to some of these tubes.  I know that some 
> manufacturers have gotten on the Russian tube band wagon and then the 
> source seems to dry up.  I am concerned about the cost of re-tubing...the 
> life of these tubes (could be years or decades I am sure) and what the 
> deal is with the Russian tube vs Eimac thing is all about.  Why is there 
> such a move to these types of tubes?
>
> I am just doing some research and asking questions.
>
> Lee - K0WA
>
>
>
> In our day and age it seems that Common Sense is in short supply.  If you 
> don't have any Common Sense - get some Common Sense and use it.  If you 
> can't find any Common Sense, ask for help from somebody who has some 
> Common Sense.  Is Common Sense divine?
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