National NC-120 manual
 

I am restoring a National NC-120 receiver. I understand this type was
used by the US Navy during World War 2. I need a repair manual with
test information such as tube socket voltages and a schematic with
component values. One similar to the ones I have for my BC-348 R and
Bendix RA-1B that has pictorial drawings of component placement and
arrangement of wiring would be great. Also any advice from anyone with
experience with this model will be appreciated. So far I have found the
power supply voltage to be about 220 DC and all the tubes test OK, but
some of the socket voltages seem wrong to me but I am not a radio tech.
The radio was working and just faded out.

Thanks
Don VE1DLT

National NC-120 manual
 

Don, The manual can be found on the BAMA website. I have overhauled
two HQ-120's and found that, on both, 100% of the capacitors had to be
replaced, along with a few resistors. I have to say that after the
re-capping, they now function extremely well. The HQ-120 was used by
the Navy as the RBG-2 and, generally, had a large metal tag or screened
label with the Navy nomenclature on it. The Navy version also had some
ruggedized transformers in them. I'll also add that the HQ-120, and
most other equipment from this era, like to be run on 110v. At 120v or
higher, they can run very hot and cause stress. I use a 15A Variac on my
"vintage line voltage bus" to keep things cool and calm.
Good luck with your project.
de Jeep/K3HVG

Don wrote:
I am restoring a National NC-120 receiver. I understand this type was
used by the US Navy during World War 2. I need a repair manual with
test information such as tube socket voltages and a schematic with
component values. One similar to the ones I have for my BC-348 R and
Bendix RA-1B that has pictorial drawings of component placement and
arrangement of wiring would be great. Also any advice from anyone with
experience with this model will be appreciated. So far I have found the
power supply voltage to be about 220 DC and all the tubes test OK, but
some of the socket voltages seem wrong to me but I am not a radio tech.
The radio was working and just faded out.

Thanks
Don VE1DLT

National NC-120 manual
 

K3HVG ) writes:
Don, The manual can be found on the BAMA website. I have overhauled
two HQ-120's and found that, on both, 100% of the capacitors had to be
replaced, along with a few resistors. I have to say that after the
re-capping, they now function extremely well. The HQ-120 was used by
the Navy as the RBG-2 and, generally, had a large metal tag or screened
label with the Navy nomenclature on it. The Navy version also had some
ruggedized transformers in them. I'll also add that the HQ-120, and
most other equipment from this era, like to be run on 110v. At 120v or
higher, they can run very hot and cause stress. I use a 15A Variac on my
"vintage line voltage bus" to keep things cool and calm.
Good luck with your project.
de Jeep/K3HVG

But he's talking about a National NC-120, not a Hammarlund HQ-120. Maybe
he's mixed up about the receiver he has, but that seems a stretge.

Michael VE2BVW

Don wrote:
I am restoring a National NC-120 receiver. I understand this type was
used by the US Navy during World War 2. I need a repair manual with
test information such as tube socket voltages and a schematic with
component values. One similar to the ones I have for my BC-348 R and
Bendix RA-1B that has pictorial drawings of component placement and
arrangement of wiring would be great. Also any advice from anyone with
experience with this model will be appreciated. So far I have found the
power supply voltage to be about 220 DC and all the tubes test OK, but
some of the socket voltages seem wrong to me but I am not a radio tech.
The radio was working and just faded out.

Thanks
Don VE1DLT

National NC-120 manual
 

Wooops..... Wrong radio!!!!

National NC-120 manual
 

"Don" wrote in message
ups.com...
I am restoring a National NC-120 receiver. I understand
this type was
used by the US Navy during World War 2. I need a repair
manual with
test information such as tube socket voltages and a
schematic with
component values. One similar to the ones I have for my
BC-348 R and
Bendix RA-1B that has pictorial drawings of component
placement and
arrangement of wiring would be great. Also any advice from
anyone with
experience with this model will be appreciated. So far I
have found the
power supply voltage to be about 220 DC and all the tubes
test OK, but
some of the socket voltages seem wrong to me but I am not
a radio tech.
The radio was working and just faded out.

Thanks
Don VE1DLT

I did a little web searching (always worth doing) and
found a page dedicated to this receiver at:
http://oak.cats.ohiou.edu/~postr/bapix/NC120RAO.htm

The site refers to the BAMA site and I was able to find a
handbook at:
http://oak.cats.ohiou.edu/~postr/bapix/NC120RAO.htm Listed
as the RAO, which was the Navy designation for this
receiver.
This, like much other material on the BAMA site is in the
form of a Dejavu document and needs Djvu to open. This is
available as freeware at http://windjview.sourceforge.net/
Unfortunately, the digital compression of this program is
such as to make schmatics a bit blury and hard to read.
The NC-120/RAO is essentially the same receiver as the
NC-100AX. There is also a handbook for this and for other
versions, I would get all because one or the other will
fill-in info missing from a particular one. Unfortunately,
the main NC-100/101 handbook is really a condensation of
material about 2 similar but not identical receivers. The
NC-100 is the one with the large calibrated dial, the 101
was a ham band only receiver with a PW dial on it. There
appear to have been a number of variations of the receiver,
with different locations for some of the controls. The BAMA
site also has a handbook for the NC-100ASD, essentially the
same except for covering 100-400 Khz instead of the
broadcast band.
Good luck with this thing, I haven't seen an NC-100 for
quite some time but have always been intrigued by them. The
later NC-200 and 2-40D were based on this basic design with
more elaborate tuning arrangements.


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Richard Knoppow
Los Angeles, CA, USA