National NCX3

[kc4umo]

Picked up a NCX3 with power supply along with a EICO 460 scope yesterday for 50 bucks.
Funny thing is both units work. Go figure....

Few questions about the NCX3.
How do they sound on AM?
I hear they had problems in the keying tube circuit, any mods to prevent this?

The rig looks pretty good for it's age.  There are a few rust spots on the cabinets but a light buffing removes it. It shows the signs of a radio that has been stored for a long time. Scratchy pots, s-meter does not move, bad connections on the rear jones plug due to oxidation.

One thing I did notice was I could not drop the carrier on ssb when I did a quick transmit test. I have not even looked at the manual yet so will do that today so I can get myself up to date on this rig.



Hoping I can clean it up because I want it as stock as possible. Going to order new caps for the rig and supply. There is bit of a AC hum on the receive.

My shack has been out in the shop for the last 15 years. Since all the kids have moved out I started a little shack in the house. Mostly old tube stuff. This rig should fit right in with my Swans, Siltronix, Yaesu's and Kenwoods.

[Pete, WA2CWA]

At one time I had two of these. Picked up the first one back in 69 or 70. Still have one here. Transmit AM is terrible. Transmits only on one sideband. Receiving AM is just as flaky. Have to tune off the center frequency for "decent" audio. Balanced modulator circuitry is not for the inexperienced. Weak 7360 in the circuit is common. This was National's first venture into an amateur transceiver. As such, they issued a number of service addenda, hints, fixes, etc. Transmit adjustments are critical and need to be done quickly. Those sweep tubes won't take much punishment. On many units, the PA TUNE can't make a complete 180 degree adjustment because the blades of the variable cap hit the top of final amplifier cage. Don't rely on the ground connection in the cable harness between the power supply and the rig. Run a separate ground buss between the two units. No RIT control, so on CW and SSB, you have the tendency to walk around the frequency to keep the contact in tune which then causes the other station to have to retune and on and on.

[kc4umo]

Hi Pete, pretty much what I expected to hear.
Fits right in with rest of my old gear lol.
Anyway it will be a keeper. I will restore it and sit it with rest of my junk.

Thanks for the tip on the ground and PA tune cap. I will check that out. Sounds like that would be nasty!

[w1vtp]

Agree with everything Pete said. We have someone who checks into the Green Mountain Net with one occasionally - way too much upper sideband component due to misalignment of the carrier oscillator and lots of distortion products. 

Be prepared to keep feeding finals to it. Be careful about tuning / loading and be good with the complete alignment.  I'm wondering if EICO was looking over National's shoulders when they designed the 753

Oh yeah, those balanced beam tubes are EXPENSIVE ($25 - $40) for what they are!

Al

[kc4umo]

Thanks for the conformation Al.
Looks like after the restore this will go on the shelf with some other unused equipment.
Maybe one day I will run across a decent AM rig.

BTW Pete I see what you mean about the PA tune hitting the cage. Really no way to solve that other than hacking it up. Which I will not do. 3/16 spacers will raise the cage enough to give clearance

[w1vtp]

Good winter project - fix the ole girl up.  Maybe you will run across a guy who wants it in his collection

a

[K4RT]

That's a nice looking transceiver and power supply/speaker. A high school friend had the NCX3. It was a reliable transceiver, and the only shortcoming I can recall now that he mentioned back then was that the NCX3 did not have CW side tone. I think he may have added a simple side tone circuit.

Since your transceiver is generally in good operating condition I wouldn't get bogged down with the minuses. Fire it up and make contacts. Try AM using one sideband if that's what it will do and find out if it sounds good or bad. If those sweep tubes are good, treat them well and they will last a long time. If the NCX3 manual doesn't provide a lot of info about loading the PA tubes, there's literature on the web and probably advice here on amfone about the proper care and feeding of sweep tubes in RF service. Pick up a few spares when you find them at a good price.

My Swan transceiver has some of the typical deficiencies of 70s SSB transceivers, and it needed some work when I bought it.  But it's a fun rig to use on air. It is not a CW man's rig, but I do use it on CW as well as SSB.  Like vintage AM transmitters, I think you have to appreciate SSB transceivers from the 60s and 70s for what they were at the time.

[kc4umo]

Good winter project - fix the ole girl up.  Maybe you will run across a guy who wants it in his collection

a

Yep, good idea. The only other National rig I have is a 98 receiver. Works ok. Restored it a bit ago. So maybe  good idea to find someone that loves these.

As far as projects? I have plenty along with repair work. I have a few more Swans and FT-101's to finish. But it is very relaxing working on these old things.

So are there any decent AM transceivers out there I should be looking for? Separate's are ok for the shop but for the house I like a transceiver. My old Apaches are just too big for the wife to look at Plus I never found a receiver yet.

[Pete, WA2CWA]

Agree with everything Pete said. We have someone who checks into the Green Mountain Net with one occasionally - way too much upper sideband component due to misalignment of the carrier oscillator and lots of distortion products.  

Be prepared to keep feeding finals to it. Be careful about tuning / loading and be good with the complete alignment.  I'm wondering if EICO was looking over National's shoulders when they designed the 753

Oh yeah, those balanced beam tubes are EXPENSIVE ($25 - $40) for what they are!

Al

The NCX-3 was introduced into the market in December 1963.

The NCX-3 uses 6GJ5 finals. Tube Depot sells them for about $10.
The 7360 typically sells from $40 to $60 each.
However, if you're willing to do a little re-wiring, the 6JH8 will work as a replacement and typically sells for around $7.

I had this in my notes from somewhere a number of years ago:

The 6JH8 can be retrofitted into any transceiver employing the 7360 tube. There are no circuit changes other than the tube socket pin wiring (see chart below) all other components remain the same. This requires all pins except the two filament pins rewired.

7360     FUNCTION              6JH8
PIN 1    CATHODE               PIN 7
PIN 2    SCREEN GRID           PIN 3
PIN 3    CONTROL GRID          PIN 6
PIN 4    FILAMENT              PIN 4
PIN 5    FILAMENT              PIN 5
PIN 6    PLATE #1              PIN 8
PIN 7    PLATE #2              PIN 9
PIN 8    DEFLECTOR #1          PIN 2
PIN 9    DEFLECTOR #2          PIN 1


The rig has no CW sidetone but, depending on the power supply, you can sometimes listen to the power transformer as you key the rig.

[Pete, WA2CWA]

So are there any decent AM transceivers out there I should be looking for? Separate's are ok for the shop but for the house I like a transceiver. My old Apaches are just too big for the wife to look at Plus I never found a receiver yet.

The majority of the 60's and 70's transceivers were designed with SSB and CW only in mind. With some work, some of these rigs can be made to sound somewhat "decent" on AM. I believe ER had some articles on making some Drake rigs sound "decent" on AM. Then there's the Yaesu FT-101 series that many use with some modifications on AM.

The best sounding AM 70's rig that I still own is the Kenwood Twins (R-599D and T-599D). The R-599A and T-599A are the same rigs except for some cosmetic changes. And, stock, they come with AM, CW, and SSB filters in both the receiver and transmitter. If you're lucky, you can find them with the correct cable to turn them into a transceiver. They pop up for sale from time to time.

[MikeKE0ZUinkcmo]

The NCX-3 wasn't intended as "the final solution", its a basic entry level transceiver and certainly from today's perspective, it shows.   It only has one filter, so AM audio response isn't HiFi, and only one sideband is transmitted.  Many "better" SSB/CW receivers of the era also had narrow "SSB" I.F.s with the same tune in one sideband at a time AM issue.

Many companies used sweep tube finals because they could get good sideband PEP output with cheep tubes, and constant carrier AM output levels suffered as a result.   You have to pay a little more attention to plate current during tune-up, but thats it.   Keep in mind most "everybody" thought AM would be dead soon, so why accommodate it.

Engineering notes/mods, and there aren't all that many, are on the web and google will find them.    Go through it, incorporate the changes, make sure all is OK, and use it.

In addition to the 599 twins Pete mentioned, Gonset's "twins" are another small, though AM only pair to  consider.   They are well designed and reliable classics.

[kc4umo]

The NCX-3 wasn't intended as "the final solution", its a basic entry level transceiver and certainly from today's perspective, it shows.   It only has one filter, so AM audio response isn't HiFi, and only one sideband is transmitted.  Many "better" SSB/CW receivers of the era also had narrow "SSB" I.F.s with the same tune in one sideband at a time AM issue.

Many companies used sweep tube finals because they could get good sideband PEP output with cheep tubes, and constant carrier AM output levels suffered as a result.   You have to pay a little more attention to plate current during tune-up, but thats it.   Keep in mind most "everybody" thought AM would be dead soon, so why accommodate it.

Engineering notes/mods, and there aren't all that many, are on the web and google will find them.    Go through it, incorporate the changes, make sure all is OK, and use it.

In addition to the 599 twins Pete mentioned, Gonset's "twins" are another small, though AM only pair to  consider.   They are well designed and reliable classics.

Thanks,
I am going to look around for the Kenwood twins and Consets twins.
 They look like they would be up my ally. Of coarse they would need to be fixer uppers. I buy nothing working. I always felt that getting to know your rig comes by having to repair it.

Still at mixed feelings over hte ncx3 but like my old Swans a lot of folks dont like them, but I do.

Thanks for the pointers guys.

[wb1ead]

I've never actually owned either the NCX-3 or it's big brother the NCX-5..however they both resided here for awhile in repair status and some on air time too..I sorta liked the NCX-5 better than the 3..probably because of the full band selection..both had the audio described by others here..transmit and receive..having said that I can tell ya about an even earlier trcvr that doesn't get mentioned much..I DID own this and it's matching supply..the NC-200..not to be confused with the rcvr that has the same number..it sported 6GJ5's also but the audio on both rcv and tx was way better overall in my opinion..and the feature I especially liked was the lower rcv noise floor..it would be worth investigating if if you can find one..why it differed I'm not sure..possibly a different design or I just got a gud one??..I love Al's comment and have to agree..I GAVE away my 753 in working order..not gonna run up and down the band with that..all the other comments too are spot on....have fun!!  73 de DAVE

[kc4umo]

Thanks Dave for that reply.

So I was thinking this morning. Scary huh?
I always loved tube gear and have all my life. But since I had my ham license I always have been a VHF guy. Mostly in satellites communications, actually before I have my ticket I helped a friend of mine for years during field day. When the Yaesu ft-736 came out I wanted one bad.  At the time I was running a 221r and an Echo 70cm transmitter. Later I got a FT-726 then finally found a 736.
With the lacking of satellites and HEO stuff I am thinking of putting my 736 up for sale or trade and find a decent AM station.
Just sitting on the shelf and has not been used in a year now since my interest has changed to HF.


I really like the looks of those Kenwood twins.... And yes, it is all about fun!

[Pete, WA2CWA]

I've never actually owned either the NCX-3 or it's big brother the NCX-5..however they both resided here for awhile in repair status and some on air time too..I sorta liked the NCX-5 better than the 3..probably because of the full band selection..both had the audio described by others here..transmit and receive..having said that I can tell ya about an even earlier trcvr that doesn't get mentioned much..I DID own this and it's matching supply..the NC-200..not to be confused with the rcvr that has the same number..it sported 6GJ5's also but the audio on both rcv and tx was way better overall in my opinion..and the feature I especially liked was the lower rcv noise floor..it would be worth investigating if if you can find one..why it differed I'm not sure..possibly a different design or I just got a gud one??..I love Al's comment and have to agree..I GAVE away my 753 in working order..not gonna run up and down the band with that..all the other comments too are spot on....have fun!!  73 de DAVE

The NCX-3 (3 band coverage) was announced in 1962 and hit the market in 1963. It was followed by the five band NCX-5. The NCX-200 came out some time in 1967. There was also the NCX-500. The 200 and 500 had pretty much the same physical cosmetic style. All of these rigs used sweep tubes in the final. In my opinion, of the four, the NCX-5 gave the best performance "bang for the buck". National also had the short-lived NCX-1000.

Note that initially, the NCX-200 was advertised as a NC-200. Evidently, someone in the advertising department dropped the "X" in the model number. And, to add to the confusion of this model, the tags on the transceiver just said "National 200". The NCX-200 transceiver uses 6JB6's.

The NCX-5 is by far one of National's best transceivers. With it's mechanical digital dial, solid-state VFO, 2 RF stages, and innovative features, it still plays quite well in today's amateur radio environment.

[Pete, WA2CWA]

I really like the looks of those Kenwood twins.... And yes, it is all about fun!

Ten or fifteen years ago, you could generally buy the "A" or "D" Twins for around $200 to $250 for the pair. Today, these same rigs are typically commanding $400 to $500 for the pair. Stay away from original Twins (the ones that have no "A" or "D" suffix) unless they're really dirt cheap. Kenwood made a number of improvements in the "A" and "D" models.

[MikeKE0ZUinkcmo]

Not much of a National guy, but I've owned NCX-3, NCX-5,  and NCX-500 National transceivers over the last decade or so, and have to agree the NCX-5 is the best of the bunch.   I've thought about modifying the NCX-5 with an additional wide filter for AM a couple of times, no burning desire to do so, but it might be an interesting project.   

[Pete, WA2CWA]

Over the years I've had 2 NCX-3's, 3 NCX-5's, 1 NCX-200 (it was a dog), 3 NCX-500's, and 1 NCX-1000 (lots of problems). All I have left is 1 NCX-3 and 1 NCX-5. Both with PS/Speakers, External VFO for the NCX-5, and walnut cabinets for the VFO, PS/Speaker, and either the NCX-3 or NCX-5.

[Opcom]

Is that set one of those that you can change a little to let both sidebands through with the carrier?

In that particular kind i refer to, a diode or switch selects one sideband filter or the other, and the carrier is re-inserted downstream for AM.  A buffer such as emitter follower or the like is used to present a load to each filter, then the outputs were combined. That way DSB+carrier AM was accomplished from the typical "AM Compatible" unit for RX and TX.

Just curious about that one.

[KA8WTK]

My first HF rig was a NCX-3, made my first CW contact on it. Sold it a while ago and then got the itch to have one again. Found one with supply/speaker in original box with all docs and mods documentation. It needs some TLC, but the nostalgia value is there.

Bill KA8WTK

[MikeKE0ZUinkcmo]

I buy nothing working. I always felt that getting to know your rig comes by having to repair it

I generally do the same, for the reasons you mentioned, and, its cheaper.  I've bought most all my test gear the same way.

Still at mixed feelings over the ncx3 but like my old Swans a lot of folks don't like them, but I do.

You won't know till its had a good rehab and honest audition, if you're underwhelmed, you might even make a little money selling a nicely refurbished properly operating BA.   

[kc4umo]

I buy nothing working. I always felt that getting to know your rig comes by having to repair it

I generally do the same, for the reasons you mentioned, and, its cheaper.  I've bought most all my test gear the same way.

Still at mixed feelings over the ncx3 but like my old Swans a lot of folks don't like them, but I do.

You won't know till its had a good rehab and honest audition, if you're underwhelmed, you might even make a little money selling a nicely refurbished properly operating BA.   

Yep, as soon as I can get more capacitors ordered I plan on getting this radio up to snuff. Going to give her a bath this week end and see how it turns out. once it is all fixed up I will play around with it a few weeks and see if it gows on me lol.  If not, down the road it will go. 

Been searching the web the last few days looking.  not seeing much out there for fixer uppers.
Time to take a drive to some of the older gents in the area and see what they have hidden.  There has to be a BA out there with my name on it

[kc4umo]

Well I decided for the time being I am going to set 2 of the 4 101's I have up for AM. I have 3 AM filters here. I am looking at setting up one with mods I found on the net and leaving the other stock. Just for comparison.

Also the National ncx3 is starting to grow on me. Think I may keep it. Hey, it was there first one on a ham tranceiver.

Anyway I hear a lot of good things about the 101's on AM.  At least that will get me on the air untill something better comes around.  In the process today of building shelves to hold rest of these rice boxes and a few other rigs, All tube so they will keep the room warm when it gets cold in a few months.

[MikeKE0ZUinkcmo]

I've been mildly interested in a 101 and am trolling for one on the bay.   this site has a fair amount of information on the various models/configurations.   I have an old Clipperton L sitting on the shelf that needs an exciter.

[kc4umo]

I've been mildly interested in a 101 and am trolling for one on the bay.   this site has a fair amount of information on the various models/configurations.   I have an old Clipperton L sitting on the shelf that needs an exciter.

That site has a lot of good info on it. There is another site that follows through  with transmit issues, just cant find it at work but very helpful.
They seem to be tough old radios for what they are.

That Clipperton should do a good job with it. Just be careful with the bay ones. I seen a lot of trashed one come from there.