NC-400

[W3SLK]

One of the many items I acquired from Joe, N3IBX(SK)'s estate was  his NC-400. I have always enjoined using a National receiver and he had both the -400 and an HRO-500. I never used either so I was rolling the dice sort of speak. I read where the HRO suffered from issues of transistors coming out of their sockets so I opted for the -400. I can say with much fanfare that this is a premium player when it comes to receivers. The example I will cite here: Last night while listening on 160M Don, K4KYV was strapping as usual on 1885. At the same time, the 'boys from NE' were on 1880. 2 powerhouse QSO's going on with exceptional fidelity at both frequencies. I was able to discern both the QSO's without interference or hetrodyning from the other. Although I just put this box into service 2 days ago. I am pleased with its performance. I saw where John, W3JN had complimented it well and that was the reason to see for myself. Any other interesting input I will gladly entertain.

[WQ9E]

I have a NC-400 also and it does a lot of things extremely well.  Selectivity is excellent for all modes and the only issue I have found is they can suffer some frequency instability on 15 and above.  It was primarily intended for service in a diversity setup with an external oscillator so maybe stability of the internal HFO was less of a concern.  I understand the fix is to drill out all of the rivets in the front end area and replace with screws, lock washers, and nuts.  Since mine is dead stable on 20 and below and rarely jumps on 15 meters I am not going to that level of invasive work.

The HRO-500 is also a neat set, I have a couple of them and both required some parts replacement but only one transistor was problematic.  But I think the NC-400 is easier to work on (unless you want to try to re-ground the front end) and it plays very well.

Rodger

[W3SLK]

Rodger said:

I have a NC-400 also and it does a lot of things extremely well.  Selectivity is excellent for all modes and the only issue I have found is they can suffer some frequency instability on 15 and above.  It was primarily intended for service in a diversity setup with an external oscillator so maybe stability of the internal HFO was less of a concern.  I understand the fix is to drill out all of the rivets in the front end area and replace with screws, lock washers, and nuts.  Since mine is dead stable on 20 and below and rarely jumps on 15 meters I am not going to that level of invasive work.

The HRO-500 is also a neat set, I have a couple of them and both required some parts replacement but only one transistor was problematic.  But I think the NC-400 is easier to work on (unless you want to try to re-ground the front end) and it plays very well.

Hi Rodger! First, I don't know why Steve moved the thread here from the 'Receiver' section but hey, what the heck! I can't remember the last time I did any AM work above 40M so like you I will leave a sleeping dog lie. I am impressed like you with the overall response of the unit. I will say that I never worked with the HRO-500 so I am a little prejudiced. The one thing I couldn't help but note is that the NC-400 seems to be in the same cabinet as the NC-300 only with a slightly different paint scheme. I have a HRO-50 that I resurrected from the dead. I have to re-align it but it is a good player if you can get past swapping out coil sets. I have a-183D that was my favorite until the power transformer went. I still have to find a replacement.

[WQ9E]

When you find a replacement transformer for your 183D, make sure that if the .1uf from one rectifier plate to ground is still in there to clip it out.  Its only use is to companies who sell or rewind transformers because it will take out a transformer before the fuse has a chance to open.

And I have yet to work on a NC-183D that didn't have badly drifted 47K resistors in the RF and IF sections which kill gain and sensitivity.  I found that issue with my NC-183D along with one I repaired for another ham and with the NBS and diversity modified (by Northern Radio) NC-183D variants I own.  Most of those resistors end up in the 200K plus range.

Rodger

[Pete, WA2CWA]

From the AM Handbook - RECEIVERS - Forum - How to Use This Section - Read Before Posting - dated January 17, 2011:

Please direct comments, questions, and other technical discussion to the Technical Forum. The Handbook Forum is for sharing complete, ready to use information, modifications, building projects, etc. If in doubt, post it in the Technical Forum. The AM Forum Administrators will gladly move posts from the Technical Forum into the Handbook Forum, if deemed appropriate.

[Steve - K4HX]

Not to beat a dead horse but I see this fairly often - questions posted in the Handbook section. Not the end of the world but the Handbook section is for reference, that is, I have a question about the NC-400. Oh, I see, W3JN did a write up in the Receivers section, let me check that out.