National NC300 restoration hints needed.
 

Gentlemen and any Ladies,

I have a National NC300 that I will be restoring. At minimum replacing the
electrolytic capacitors. What other Hints and Kinks should I be aware of
before I get into this exciting restoration project?

Were there any popular mods to this radio?
Are there any particular problems like a known arching wafer switch?
Etc., Etc.

Thanks in advance,

Paul P.

National NC300 restoration hints needed.
 

In article eMxvk.490$Wd.356@trnddc01,
"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom writes:
Gentlemen and any Ladies,

I have a National NC300 that I will be restoring. At minimum replacing the
electrolytic capacitors.

Glad you brought that up. I have a couple of antique radios I would like to
restore. All of them need replacements for the big can multi-section caps
in the power supply. Where does one find replacements for these today?
I just got a brand new Allied Catalog (I didn't even know they were still
in business) but they have nothing even vaguely similar.

One of these radios is very valuable to me sentimentally as it was the first
radio I ever repaired, when I was 9 years old. It is an old Philco and
listening to shortwave after repairing it is probably what got me interested
in electronics and radio in the first place.

bill
KB3YV


--
Bill Gunshannon | de-moc-ra-cy (di mok' ra see) n. Three wolves
| and a sheep voting on what's for dinner.
University of Scranton |
Scranton, Pennsylvania | #include std.disclaimer.h

National NC300 restoration hints needed.
 

Bill Gunshannon wrote:
In article eMxvk.490$Wd.356@trnddc01,
"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom writes:
Gentlemen and any Ladies,

I have a National NC300 that I will be restoring. At minimum replacing the
electrolytic capacitors.

Glad you brought that up. I have a couple of antique radios I would like to
restore. All of them need replacements for the big can multi-section caps
in the power supply. Where does one find replacements for these today?
I just got a brand new Allied Catalog (I didn't even know they were still
in business) but they have nothing even vaguely similar.

Antique Electronics Supply has them, but you can scoop the insides out of
the old cans and solder new caps in there, if you want the same appearance
for less money.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

National NC300 restoration hints needed.
 

"Bill Gunshannon" wrote in message
...
In article eMxvk.490$Wd.356@trnddc01,
"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom writes:
Gentlemen and any Ladies,

I have a National NC300 that I will be restoring. At minimum replacing
the
electrolytic capacitors.

Glad you brought that up. I have a couple of antique radios I would like
to
restore. All of them need replacements for the big can multi-section caps
in the power supply. Where does one find replacements for these today?
I just got a brand new Allied Catalog (I didn't even know they were still
in business) but they have nothing even vaguely similar.

One of these radios is very valuable to me sentimentally as it was the
first
radio I ever repaired, when I was 9 years old. It is an old Philco and
listening to shortwave after repairing it is probably what got me
interested
in electronics and radio in the first place.

bill
KB3YV


I like your sign.

Good ones are scarce. New old stock dries up. There are some twist-lock
still being made but hard to find in the combination you need. One way is
to fudge the values or make changes in the power supply to make use of what
is available. Some just leave the can in for show and put single section
replacements below the chassis. Fortunately newer caps can be made smaller.
Sometimes you can fit the smaller axial and pc mount styles into the
hollowed out original. Hot glue and perfboard can help. I have even heard
of people gluing or waxing the original around the new ones for show.


| de-moc-ra-cy (di mok' ra see) n. Three wolves
| and a sheep voting on what's for dinner.
and freedom is a well armed sheep contesting the vote.

National NC300 restoration hints needed.
 

"Bill Gunshannon" wrote in message
...
In article eMxvk.490$Wd.356@trnddc01,
"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom writes:
Gentlemen and any Ladies,

I have a National NC300 that I will be restoring. At minimum replacing
the
electrolytic capacitors.

Glad you brought that up. I have a couple of antique radios I would like
to
restore. All of them need replacements for the big can multi-section caps
in the power supply. Where does one find replacements for these today?
I just got a brand new Allied Catalog (I didn't even know they were still
in business) but they have nothing even vaguely similar.

One of these radios is very valuable to me sentimentally as it was the
first
radio I ever repaired, when I was 9 years old. It is an old Philco and
listening to shortwave after repairing it is probably what got me
interested
in electronics and radio in the first place.

bill
KB3YV

Bill,

I'll let you know how I handle the electrolytic. Either I will restuff the
cans or place new ones under the chassis and abandon the cans in place. See
my web site for cap can restuffing;
http://www.ppinyot.com/C/capacitor_stuffing.htm (This is a hobby site.
Nothing for sale).

Paul P.

National NC300 restoration hints needed.
 

On Sep 3, 11:08*am, "Paul P" REMOVE paul @ REMOVE ppinyot .
REMOVEcom wrote:
Gentlemen and any Ladies,

I have a National NC300 that I will be restoring. *At minimum replacing the
electrolytic capacitors. *What other Hints and Kinks should I be aware of
before I get into this exciting restoration project?

Were there any popular mods to this radio?
Are there any particular problems like a known arching wafer switch?
Etc., Etc.

Thanks in advance,

Paul P.

I restored one (partially) a few years ago, and that is still my AM
receiver. I actually never replaced the filter caps, but the only time
I notice much hum is if I use headphones.
There is a mod for changing the AGC so it works better for SSB, and I
did that. The S-meter still has very fast action on SSB, but I don't
hear the constant "pumping" now. If you are interested, I can try to
find that mod.
Mine had a broken crystal phasing cap that might have happened in
shipping. (I never found out just what happened)
I cemented it back together, but getting the crystal filter aligned
perfectly was a nightmare. All the adjustments interact so you adjust
one and it throws the other off. If the crystal filter seems to work
fine, I would suggest leaving it alone, or else maybe use a sweep
generator. The rest of the radio isn't hard to re-align.
I repainted mine, so it looks real good now. Luckily the front panel
was almost perfect, even though the cabinet needed a paint job.

Good luck and 73,
Al

National NC300 restoration hints needed.
 

On Sep 3, 8:08*am, "Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom
wrote:
Gentlemen and any Ladies,

I have a National NC300 that I will be restoring. *At minimum replacing the
electrolytic capacitors. *What other Hints and Kinks should I be aware of
before I get into this exciting restoration project?

Were there any popular mods to this radio?
Are there any particular problems like a known arching wafer switch?
Etc., Etc.

Thanks in advance,

Paul P.

Paul,


Yes I change the electrolytics with out of the junk box, some
reformed, some new. If I don't have the value I make one up out of
series/parallel combinations. I don't think there were too many paper
caps but if there were change them too.

Use Deoxit on the band and wafer switches but not too much.

The NC-300 was a nice radio for it's time in that it had a proiduct
detector for better cw and ssb but no agc to match. A simple diode was
added in the NC-303 to provide a rudimentary fast attack agc. I
compared the NC-303 schematic to the NC-300 and added it with great
results on ssb and cw. Add it and you will have an NC-300 +1/2!

Good luck on your project.


Tony WA6LZH

National NC300 restoration hints needed.
 

Thank you all for the replies.

I printed out the BAMA schematics and the BAMA
http://bama.edebris.com/manuals/ mods for the NC300. The mods are numerous.
This chassis has none of them. This can be good or bad depending on the
collectors desires. I would think the factory mods like replacing an
unshielded wire with shielded wire would be totally collector acceptable.
The mod is fixing a design flaw identified by the factory.

I dim bulb (a kin to a variac) tested and opened up the NC300 today to start
the restoration. I was able to receive station but the dial is way off and
was unable to clarify SSB. All tubes tested good save one. The mixer is
bad. I cleaned the chassis with Clorox clean up, a tooth brush and a rag.
Now it is nice and shiny.

There is plenty of room under the chasssis for new Electrolytics. Since
this restoration will not have restuffed wax/paper caps I see no harm in the
underchassis installation. If a collectors want a "museum" level
restoration to show off the underside of the chassis then all new components
would be hidden inside origonal container, wrappers or what have you.
Reformation of the eletrolytic can is out of the question. There is dried
eletrolyte harded on the vent hole. In my not so hmble opinion - Unless I
have a published life expetancy of the capacitor or the dilectric you are
asking for a recall or burned out components when that capacitor evenually
dries up, shorts or burns up.

There are a lot of paper capacitors underside. They are dipped in some
plastic like coating. But that does not stop the deterioration of the
internal paper. Here again, I think it is best just to "shot gun" them out.

I have a habit of resistor replacement as well. This is a bit on the edge
of needs to be done or not. My lesson came from an RCA AA5. I replace all
caps and aligned. It played for a day and failed. I put it on the bench
and found the out of tolerance resistor. It measued good along with all the
rest. I repeated these steps three more times before I just decieded to
shot gun the carbon composition resistors. No more problems. If I find any
out of tolerance reisstors in this chassis I will go ahead and shot gun
these too. The chalenge is not to uses inducive carbon film resistors in
high frequency (relative to the resistor) circuits like the oscillator and
mixer section. I found that in radios that recieve less than 18 mhz all is
ok. Any thing above that then non inducive resistors must be maintianed.

More later, and thanks again to all whom contributed.

If you want to follow along I will be posting my progress on the web site at
www.ppinyot.com. It is not there yet.

Paul P.

National NC300 restoration hints needed.
 

"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote in message
news:7RWvk.507$sq3.375@trnddc07...
Thank you all for the replies.

I printed out the BAMA schematics and the BAMA
http://bama.edebris.com/manuals/ mods for the NC300. The mods are
numerous.
This chassis has none of them. This can be good or bad depending on the
collectors desires. I would think the factory mods like replacing an
unshielded wire with shielded wire would be totally collector acceptable.
The mod is fixing a design flaw identified by the factory.

I dim bulb (a kin to a variac) tested and opened up the NC300 today to
start
the restoration. I was able to receive station but the dial is way off
and
was unable to clarify SSB. All tubes tested good save one. The mixer is
bad. I cleaned the chassis with Clorox clean up, a tooth brush and a rag.
Now it is nice and shiny.

There is plenty of room under the chasssis for new Electrolytics. Since
this restoration will not have restuffed wax/paper caps I see no harm in
the
underchassis installation. If a collectors want a "museum" level
restoration to show off the underside of the chassis then all new
components
would be hidden inside origonal container, wrappers or what have you.
Reformation of the eletrolytic can is out of the question. There is dried
eletrolyte harded on the vent hole. In my not so hmble opinion - Unless I
have a published life expetancy of the capacitor or the dilectric you are
asking for a recall or burned out components when that capacitor evenually
dries up, shorts or burns up.

There are a lot of paper capacitors underside. They are dipped in some
plastic like coating. But that does not stop the deterioration of the
internal paper. Here again, I think it is best just to "shot gun" them
out.

I have a habit of resistor replacement as well. This is a bit on the edge
of needs to be done or not. My lesson came from an RCA AA5. I replace al
l
caps and aligned. It played for a day and failed. I put it on the bench
and found the out of tolerance resistor. It measued good along with all
the
rest. I repeated these steps three more times before I just decieded to
shot gun the carbon composition resistors. No more problems. If I find
any
out of tolerance reisstors in this chassis I will go ahead and shot gun
these too. The chalenge is not to uses inducive carbon film resistors in
high frequency (relative to the resistor) circuits like the oscillator and
mixer section. I found that in radios that recieve less than 18 mhz all
is
ok. Any thing above that then non inducive resistors must be maintianed.

More later, and thanks again to all whom contributed.

If you want to follow along I will be posting my progress on the web site
at
www.ppinyot.com. It is not there yet.

Paul P.


I hadn't tried Clorox before. I would worry about salts appearing. Do you
flush with distilled water after that?

National NC300 restoration hints needed.
 

JB wrote:


I hadn't tried Clorox before. I would worry about salts appearing. Do you
flush with distilled water after that?

Not Clorox bleach, Clorox Cleanup. It is a spray cleaner similar to 409.

If you use Clorox bleach on aluminum, it will etch it and eat it away.

-Chuck