National Radio

NC-98 Ad

Here is an old ad from when the NC-98 was new.

Click on the image for a larger view.

NC-98 Ad

Restoration Resources


Tom's Top Picks

I've got some of my favorite radio restoration links here. Check them out!
Tom's Top Picks

Phil's Old Radios

Possibly the oldest antique radio web site on the internet. Phil has tons of great articles on how he restored vintage sets.There's lots of good info there, especially for newcomers to the hobby.

It is no coincidence that my restoration articles have a similar look and feel as Phil's. I love his site. If you do some exploring there, you'll be lost for days! Phil's Old Radios


Parts Resources

Usually, all an old tube radio needs to come back to life is a replacement of the old electrolytic and paper capacitors. A great source for these at good prices is WJOE Radio


Old Radio Restorations

Don't miss my other radio restorations - I have several listed on my "Projects" page. More…



National Radio Model NC-98

National NC-98 Receiver

I couldn't help myself...

When I saw this National Radio model NC-98 listed on EBay by a local ham, I couldn't keep myself from bidding on it. I already had an NC-125 and an SW-54, but this NC-98 had qualities of its own to appreciate. Besides, I'd been thinking about putting a little display of National receivers together for my collection. That collection just HAD to have an NC-98!

The National NC-98 is a general coverage receiver that tunes from 540 to 40000 kHz in four ranges. The amateur bands are all bandspread on a seperate dial - main tuning on the left and bandspread on the right. The band ranges are .54-1.6, 1.6-4.7, 4.7-14, and 14-40 MHz. Bandspread: 3.5-4, 6.9-7.3, 14-14.35, 20.4-21.5 and 27-30 MHz. Features include: S-Meter, Phono Input Jack, Antenna Trimmer, RF Gain, Pitch, Tone HI/LO, Standby, Dial Lamp, Sensitivity and Hinged Top Cover.

Although lacking the "Select-O-Ject" circuitry of the NC-125, the NC-98 sports a crystal filter which helps seperate close signals. The NC-98 is basically an improved version of the NC-88. It adds an S-Meter as well as the crystal filter, but does not have an internal speaker, as the NC-88 does.

This model does suffer a bit from mechanical instability - pushing on the case can shift the receive frequency a bit. Still, it is usable as a ham receiver and does very nicely as a general coverage receiver for AM broadcast and international broadcast listening.

Technical Details

The NC-98 is a nine tube, single conversion receiver with a 455 kHz. intermediate frequency. The tube lineup is as follows:

Tube	Type	Function

V1	6BA6	RF Amp
V2	6BE6	Mixer
V3	6C4	Oscillator
V4	6BD6	1st IF Amp
V5	6BD6	2nd IF Amp
V6	6AL5	Det/AVC/Limiter
V7	12AX7	Meter Amp/BFO/AF Amp
V8	6AQ5	Audio Output
V9	5Y3GT	Rectifier

If you want to work on one of these sets, service information is readily available from many sources. You can find schematics, parts, and alignment info in Photofact folder 264-14. These are commonly available through public libraries, or you can buy them from several EBay vendors. You can also download a copy of the schematic from the Boat Anchor Manual Archive (BAMA.) Get it here.

Restoration

If you are looking for a "boat anchor" type receiver to learn some tube receiver restoration basics, the NC-98 would be a good candidate. You'll want to change out the power supply electrolytics and the wax-covered paper capacitors. A lot of the caps in the NC-98 (at least in the model I restored) are ceramic disks. This type of capacitor rarely fails and should not need replacing. It is a good idea to check the resistors to see if they've drifted out of tolerance. As resistors age, they usually go up in value. On my NC-125 I had to change a lot of the resistors because they had drifted as much as 50% higher in value. I didn't have the problem with my NC-98 and left the resistors as they were.

Some Inside Views

It is always good to take a few pictures of the circuitry of any radio you are about to work on before you take a soldering iron to it. If you get interrupted in the middle of replacing components, you can always check the pictures to verify component location. Here are a few pictures of my NC-98 before I started in replacing caps:

National NC-98underside National SW-54 topside National NC-98underside National SW-54 topside National SW-54 topside

The main electrolytic caps are in a can mounted on top of the chassis. The can has 3 caps inside - all 20 uF 450 volts. I clipped off the connections on the underside of the chassis for the three cap connections and soldered a terminal strip by the old can so that I could mount new capacitors. It was fairly simple to move the old connections to my new tie points.

I've gotten most of my capacitors from three suppliers. In order of frequency:

WJOE.com
Just Radios
Bob's Antique Radio Supply

WJOE Radio has a nice assortment that you can get with or without a case. Just Radios is probably the slickest source and they have a wide variety of caps for radio restoration. Bob's Antique Radio Supply sells larger quantities of caps at good prices. You can also get them from major electronics suppliers like Mouser and Digikey.

Other Restoration Necessities

Spray some DeoxIT or other contact cleaner into the controls and onto all the switch contacts. Work them back and forth. Intermittent switches and noisy controls are easy to fix but cause many sets to be be deemed "inoperable." Do the same for the tube contacts. Most non-techie types always assume that a non-working radio is due to burned out tubes. They actually are rarely bad. Even if they are, there are millions of replacements available. The tubes in the NC-98 are not rare at all. If you find a bad one, it will be cheap and easy to replace.

In Conclusion

If you love the look of the old National receivers as much as I do, you'll have to add an NC-98 to your collection. Although not a super performer, it makes a pretty good receiver for casual listening.


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