Donald Fox wrote:
> Gentlemen:
>
> Just submitting a quick poll to see what the feeling is about making the
> swap from a pair of 3-500s to the almighty 8877.
>
Welll...
>
> The donor is my very good condx Henry 2K Classic X which I do not want to
> butcher. I am aware that the Henry consoles were oem equipped with the 8877
> and other tubes.
>
>
The Henry series runs fairly low voltage on its tubes, at least the 3-500s.
Although I think the Henry consoles make a good base (pun not intended)
for building a more powerful and rugged amp the only thing the 8877 has
to offer is lower drive. It's fragile, relative to the 3-500s and
unless you have a source it's expensive (again relatively speaking).
Most of the Henrys are of a basic, but rugged design. They are big,
heavy, run the tubes easy, and those tubes last a very long time.
Now I don't mind taking apart and modifying old amps and I don't call it
butchering... Although... I have seen a few examples where I'd make an
exception to that<:-)), but I just don't see much to gain by going to
the 8877.
I have to agree with Hsu that the 3CX-1200 would be a great start IF you
can get them at a good price. HOWEVER that would be just the start as
I'd kick up the plate voltage (New Transformer), and I'd hate to see
that one socket empty so I'd *have* to install a second 3CX-1200 with
the associated filament transformer AND a pair of chimneys. I've spent
no time with my old Eimac book looking up the specs on the 1200 so I
don't know if the bias would need changing or not. With a pair of them
there would be no need for any "visible" change in the amp when looking
at the RF deck.
I have to admit I did think about this before I sold my old 2K4. Now
OTOH for the alpha whether going from the 8874's 3CX-400's to a pair of
3CX800's at $300 plus each or the 8877/3CX-1500A7 imports and pulls
do look "Interesting".
Of course I find the Russian GU84B really INTERESTING and I think the
equivalent of a 4CX2500. BUT I'm afraid about the only thing left would
be the original 76 cabinet and the GU84B isn't exactly inexpensive.
However it's not bad at all compared to a new 8877 <:-)) and *really*
good compared to a new 3CX-1200 Of course there is the GU88...
> My goal is not for more power, but to enjoy the lower drive requirement of
> the 8877 for my IC746.
>
> I know that the filament xformer and socket would need to change as well as
> reworking the airflow for cooling.
>
Another thought is a pair or even three of the 3CX-800's or
3CPX-800's. The big fan (at least on the 2K4) should do a good job of
cooling them and they are available at a reasonable price. It would
also make a neat looking installation if used with the ceramic chimneys.
OTOH the Silastic rubber chimneys work just fine.
>
> So, can the change be done without major mods to the input/output networks??
>
>
They would probably require a bit of tuning but I'd think they'd be
within range.
The tank should be fine if staying within the original current to
voltage ratio.
> If not, then I will drop the idea and enjoy it as is. Changing to another
> amplifier is not in the budget, and since I have a soft spot for the 80's
> model Henry consoles, this one is bound to be around as long as I can afford
> it.
>
If you haven't done one before, most conversions are likely to offer a
surprise or two and remember the Henry amps had little or not protection
circuitry that you find in todays amps.
Were it me, and it's not, unless going for a major project I'd most
likely leave it as is which is what I did with my 2K4.
>
> Thanks for your comments pro or con in advance.
>
> Don N8ECH
>
>
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