At 08:37 PM 4/9/2008, Bert Almemo wrote:
>Hi guys,
>
>I have a friend who wants to replace 4x811A with 4x572B in an Ameritron amp.
>I don't think it's a good idea but he insists a lot of hams do it. What do
>you think?
>
>73 Bert, VE3OBU
It's a good move. They are physically and electrically very
close. I did it with the AL-811H and instead of going through one or
two of those Taylor Chinese clone 811As a month I never had to
replace a tube again. They are running at about 2/3 their voltage
rating (the 572Bs) in an amp designed for 811As. You can't get any
glass tubes that are made in NA anymore, but if you substitute
imported 572Bs for imported 811As.
I have since sold the amp in favour of an ACOM-1000, but the guy
who bought it a year ago still has the 572Bs in it. The only thing
is that Ameritron won't honor the warranty if you do this, so wait
until the amp is a year or more old (and thus off warranty.) I even
discussed this with one of the techies at Ameritron and he said the
switch to 572Bs was a good idea, although he couldn't "officially"
recommend it.
73, Paul VE1DX
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