John,

They are direct replacements but they aren't very good. K3FK had a QRO
amp with a pair of 'em a few years back and we had to resolder filament
pins on one or the other of the bottles several times. We dropped in a
set of Eimacs and the problem went away.

I've heard very good things about the Ampex variants with the carbon anodes.

Dave Heil K8MN

John N9JG wrote:
I am not sure if the Drake L4-B qualifies as a suitable topic for this
newsgroup, but it does use tubes and the power supply could be used as an
anchor for a small boat.

Are the Chinese 3-500ZGs a drop-in replacement for the Eimac 3-500Z in the
Drake L-4B?

John, N9JG

Thank you very much for the pointer. As I understand it, Eimac doesn't make
this tube anymore, but Ampex is a good brand. Hopefully a Google search will
find out where to buy them.

"Dave Heil" wrote in message
nk.net...
John,

They are direct replacements but they aren't very good. K3FK had a QRO
amp with a pair of 'em a few years back and we had to resolder filament
pins on one or the other of the bottles several times. We dropped in a
set of Eimacs and the problem went away.

I've heard very good things about the Ampex variants with the carbon
anodes.

Dave Heil K8MN

John N9JG wrote:
I am not sure if the Drake L4-B qualifies as a suitable topic for this
newsgroup, but it does use tubes and the power supply could be used as an
anchor for a small boat.

Are the Chinese 3-500ZGs a drop-in replacement for the Eimac 3-500Z in
the Drake L-4B?

John, N9JG

They are direct replacements but they aren't very good. K3FK had a =
QRO=20
amp with a pair of 'em a few years back and we had to resolder =
filament=20
pins on one or the other of the bottles several times. We dropped in =
a=20
set of Eimacs and the problem went away.

I had the same problem with an Eimac 3-500Z, though once only.

Tony, I0JX

Antonio Vernucci wrote:
They are direct replacements but they aren't very good. K3FK had a QRO
amp with a pair of 'em a few years back and we had to resolder filament
pins on one or the other of the bottles several times. We dropped in a
set of Eimacs and the problem went away.


I had the same problem with an Eimac 3-500Z, though once only.

Tony, I0JX

I've seen it a couple of times during the time that the Eimac tubes were
manufactured. I suspect that in all of these instances, the amplifier's
cooling system was not quite as it should have been. It is much more
likely to happen in an amp which relies upon fan cooling and less likely
in an amp using the Eimac Air System sockets and chimneys.

The Chinese tubes that K3FK had problems with were of the Penta brand.

Dave K8MN