Hi, whats the next step up in performance in a general coverage reciever? I am currently using a National NC-57 and I like it. Easy to work on, stable and performs nice. I'm curious on your opinions.

Doug

In the National line of about the same era it would probably be the NC-88. Similar qualities - easy to work on, inexpensive, etc. A bit more of a ham's receiver because it has a calibrated bandspread although its general coverage. Next would be the NC-98 which is starting to get into a quite respectable receiver.

For the same years it would be NC-173, NC-183. Both affordable, easy to work on and very good performance. The 183 audio will blow out the windows.

Im not fond of the NC-88/98 but the NC-125 is usually a sleeper on the market, all three are later than the NC-57.

A bit later still and the NC-109 is above average.

Carl

Thanks for the input. Here's another question, when does double conversion make a difference? Is it important under 30MC or just a selling point.

Doug

Makes a BIG difference. Lets take listening to hams on 20 meters, 14.0-14.3 Mcs. Most single conversion sets use a 455kc IF which means the images will fall 910kc below the fundamental. In this example there is the 19 meter shortwave broadcast band at ~15.0-15.4 Mcs. Very strong stations there will create interfering images across the 20m ham band.

Double conversion goes a long way in preventing this.

A set like the NC-57 doesn't offer much image rejection on the higher frequencies. If it were more sensitive it would be a bigger problem

Image rejection of the 57 is modest at 7mc and goes down as frequency goes up. By the time you get to 28mc the image rejection is about 12-15dB on a good day.

The NC-173 is a bit better due to the higher Q coils. And with the double preselection of the 183 its quite good.
The NC-109 can be looked at as an updated 173, it also has a product detector for SSB/CW.

Carl

The next step up in performance would be a receiver that has a crystal filter. An S-meter would be nice and so would calibrated bandspead but the improvement in selectivity that a crystal filter provides gives a huge boost in the ability to separate closely spaced stations.

Dave

I have had three NC-57's ofver the years. The third one which I own now(NC-57B) is going to be a winter project. First a recap, then replace the IF tubes with WE-717A's, fix the BFO injection level, and do a full alginment. Then plug in the SM-57 S-meter, and Selc-O-Ject. Once that's all done just sit back and tune around the bands. I must agree with all about the radio performace above 15 MC. If I were to use the radio up there a good RF preamp is called for. But a good converter would be a good choice as well. On my second radio I did a mod to the IF by adding a Mura filter. Made the IF sharp enough to copy SSB with the AF gain turned up and using the RF gain to keep the signal level in line with the BFO Level. Not the best, but for a fifteen year old fun. I am looking forward to many evenings in the shack looking at the glow of the dials and listening to the Short Wave broadcasts and the BCB.

Jeff N2LXM

Dont expect much besides distortion from the 717A's with strong signals.

With the 6SG7 and 6SB7Y front end they were the hottest of the octals. Since the 717A is a sharp cutoff any AVC applied will result in a real mess and if you eliminate the AVC control on the IF's the 6SG7 alone isnt enough. A good tuneable preamp is so much better.

Carl

I got an NC-109 based on your tips and you guys weren't kidding! A nice step up from the 57. I parked on some clubs SSB frequency around 7.1MHZ and left it there for a couple of hours and I didn't have to adjust anything except the sensitivity control as volume. Once it gets warmed up it it's nice and stable.

Thanks,

Doug

What's the audio quality out of the NC-109? I am looking for a shortwave receiver with good AM audio.
I am really spoiled with my NC-300 on AM and would like to find something that sounds as good or better
for shortwave.

thanks
Ken

Carl's suggestion about getting a NC-109 was a good one. I got mine at a hamfest from a seller who had a bunch of junk from a barn and the survivor of the group was a NC-109. I was pleasantly surprised at its post-restoration performance.

Another lower end National I like is the NC-125.

Although it is more practical to use a better receiver on the upper bands, if you are sentimentally tied to using a simpler receiver pairing it with a preselector (like one of the vintage RME DB series) will greatly improve the image rejection on the upper ranges.

Rodger WQ9E

I think the audio is good. I'm using an old four ohm Jensen R-10 field coil speaker in a box.

Hi i just about have my NC57 recapped the radio was preforming great no hum I wonder if you should not fix it unless it is broken i know that some of the paper caps could go at any time . i like the radio 73 Darryl

How do you like the NC-109 on AM? I am looking for a shortwave receiver with good audio.
Not to narrow, wide enough for good audio.

Thanks
Ken