The AM Forum

While I am waiting on parts for my pine board project build I figured I'd climb into a simple receiver repair and semi rebuild. I found this little NC-33 I found on e-bay for around 35 bucks in non working condition. I also picked up the photo-fact sheet for it. the set was DOA so i tested the tubes and believe the 35Z5 is done for, also the Power/AF gain control knob is froze up and the one of the dial cords is broken. It looks like someone has worked on it in the past, but man it looks even worse than some of my work. I've ordered some new cord, a tube set, New Caps and a new switch/pot but then i took the old one apart and was able to free it up with some good cleaning and a spot or two of deoxit.
  What I thought was a "black beauty cap" turned out to be a resistor so i replaced it too. did some re-soldering work and general cleanup to the set and now i need to replace the speaker and I found what i hope wont be too big of an issue with the main tuning air-cap. It appears that it was bumped at some point and two of the fins were making contact pretty hard. I straightened out the fin and used a xacto knife to carefully remove the burrs that were left behind. one of the fins has some pretty good scratches but i thing they are all clear from making contact with each other.
   The speaker is a Quam 5A15 with a transformer attached to it. It's a 3.4 ohm speaker and is rotted out pretty good. i have a new 5" speaker but its 8 ohm. I can use a resistor to bring it down to
3.8 ohm but I'm not sure what the transformer is for? It can be mounted on the deck as there is plenty of room.
   The case is in pretty good condition, but will need the plastic screen replaced. I really like the look of the national radios, kind of a 30's machine look. I know this thing has a floating ground and that needs to be fixed. I saw somewhere a small simple circuit to get the voltage off of the case.(maybe someone can point me to it).
  I will stop rambling on now, but i gotta say what a great way to waste a day. I started tinkering with this thing about 9 am and before I knew it most of the day was gone...

Resistors are not the way to change speaker impedance.  In your case, an 8-Ohm will work just fine.

There are several schools of thought about 'converting' an AC-DC radio to a three-wire power cord.  I won't go into that, however I've had no problems with just a polarized 2-wire cord.  Make sure all your outlets are wired correctly.

73DG

cool radio.