Looking for the specs for the 4H4-C ballast tube used in a National NC300.
I know about the 6X6 or whatever sub. I want to see why there is a 4.3 ohm
2watt resistor across said ballast tube socket. It is not reflected in the
schematic from BAMA. There is a 2.2 ohm in the schematic.

Thanks Paul P.

On Thu, 11 Sep 2008, Paul P wrote:

Looking for the specs for the 4H4-C ballast tube used in a National NC300.
I know about the 6X6 or whatever sub. I want to see why there is a 4.3 ohm
2watt resistor across said ballast tube socket. It is not reflected in the
schematic from BAMA. There is a 2.2 ohm in the schematic.

I can't give any date, but I have a vague memory of seeing an article
that described a solid-state replacement for that ballast tube. But
it's vague enough that it may be a false memory. Usually I can remember
where I would have seen such things, and I can't this time.

I just did a websearch, and nothing turns up. But, apparently that 2.2ohm
resistor was a factory mod or upgrade. Nothing on the 4.3ohm resistor
after a quick glance.

Michael VE2BVW

"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote in
message news:GXcyk.1014$393.959@trnddc05...
Looking for the specs for the 4H4-C ballast tube used in a
National NC300.
I know about the 6X6 or whatever sub. I want to see why
there is a 4.3 ohm
2watt resistor across said ballast tube socket. It is not
reflected in the
schematic from BAMA. There is a 2.2 ohm in the schematic.

Thanks Paul P.


Amperite is still in business. Their home page is at:
http://www.amperite.com
They have a technical data sheet and list of currently
available ballast tubes at:
http://www.amperite.com/Uploads/Ballasts.pdf

I don't see the 4H4-C listed but I suspect an e-mail to
the company would get you the characteristics.
A resistor across the ballast would limit the amount of
current it has to pass but would also reduce its
effectiveness.


--
--
Richard Knoppow
Los Angeles, CA, USA

National admitted the ballast did not work very well. In my opinion, the
best approach is to rectify the 12 volts, then regulate it. That will give
you a pure dc, which helps on 10 meters, where the filament hum modulates
the oscillator. Also helps stability.

There is an article on the conversion to use a regulator chip.

73, Colin K7FM

Amperite is still in business. Their home page is at:
http://www.amperite.com
They have a technical data sheet and list of currently
available ballast tubes at:
http://www.amperite.com/Uploads/Ballasts.pdf

I don't see the 4H4-C listed but I suspect an e-mail to
the company would get you the characteristics.
A resistor across the ballast would limit the amount of
current it has to pass but would also reduce its
effectiveness.


--
--
Richard Knoppow
Los Angeles, CA, USA

Richard,

Thanks for the lead. I wrote them an email inquiring as to the specs.

Thanks again,

Paul Pinyot.

"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote in
news:GXcyk.1014$393.959@trnddc05:

Looking for the specs for the 4H4-C ballast tube used in a National
NC300. I know about the 6X6 or whatever sub. I want to see why there
is a 4.3 ohm 2watt resistor across said ballast tube socket. It is
not reflected in the schematic from BAMA. There is a 2.2 ohm in the
schematic.

Thanks Paul P.





From "The Ballast Tube Handbook" by A. P. Jacobi

4H4C, use 110/1-20V sets, 4.5-8.5V, 440-470mA,
Element connected to pins 2 and 7.
No alternate type listed.

From "The Ballast Tube Handbook" by A. P. Jacobi

4H4C, use 110/1-20V sets, 4.5-8.5V, 440-470mA,
Element connected to pins 2 and 7.
No alternate type listed.





Thanks for the information

Paul P.