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Reviews Categories | Transceivers: HF Amateur HF+6M+VHF+UHF models - not QRP <5W | National NCX-5 Mark II Help

Reviews Summary for National NCX-5 Mark II
National NCX-5 Mark II Reviews: 9 Average rating: 4.4/5 MSRP: $549
Description: 80 thru 10 meter transceiver.
Product is not in production.
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N8FVJ Rating: 5/5 Oct 4, 2015 20:32 Send this review to a friend
High Output Mod  Time owned: 0 to 3 months
Change that NCX-5 into a fire breather...

The National NCX-500 is rated 125 watts AM, 500 watts PEP SSB and 390 watts CW output. The PI network parts in the National NCX-500 are the same as the NCX-5.

The power supply for the NCX-500 is the National NCXB and the power supply for the NCX-5 is National NCXA. The transformer part number is the same for both power supplies. The only difference in-between the power supplies is the HV 2-25HY swinging choke input filter in the NCXA is removed in the NCXB HV circuit and adds another 450 volt capacitor in series for 1350 volts rating. Removing that input choke increases the high voltage from 700 volts DC to 1100 volts DC. (Same voltage used in the small sweep tube amps). Also, remove the HV bleeder resistors in the NCXA power supply. These resistors are not required to meet Crit for the HC choke during receive.

The NCX-5 makes use of two 6JB6 RF amplifier output tubes. The NCX-500 uses two 6LQ6 RF output tubes. Some NCX-5 owners have replaced the 6JB6 with 6LQ6 for a heavy duty design. It is a drop-in 'plug & play' replacement and the new tubes are re-neutralized. The extra filament load of the 6LQ6s is no problem. Filament voltage holds up well due to the hefty power transformer. And, the NCX-500 uses the same transformer with a few less small tubes having a 150 milliamp 12 volt filament current.

Plenty of room exists under the power supply chassis for new capacitors. Todays capacitors are smaller for same value of vintage capacitors. I installed three 680uF @ 450 volt DC 'snap-in' type capacitors for an effective 227uF @ 1350 volts. Place a 75K @ 7 watt resistor across each 680uF capacitor. The resistors balances voltage across each capacitor & also act as a safety bleeder. Lower value balancing resistors are not needed on the new manufactured capacitors due to the leakage current is lower vs vintage capacitors.

The best RF amplifier tubes are 6MJ6 with the black anode cap. The tubes are rated 40 watts plate dissipation. However, I have no concern using 6LQ6. Due note some 6MJ6 tubes have a shiny chrome cap. These tubes are not the real RCA design 6MJ6 with a 40 watt plate dissipation.

The NCX-5 new high power output does make a difference on 75 meters at night. Use a Turner Plus 3 microphone with a built-in audio compressor for higher average SSB output. Frankly, a linear is not required in most band conditions with this NCX-5 modification. And, that Turner with audio tube amplification sounds great.
KE0ZU Rating: 5/5 Jul 16, 2012 21:52 Send this review to a friend
Great Radio  Time owned: more than 12 months
I've had two of these fine looking radios over the last ten years and as most others, wish I'd kept the first one. I've had all of National's tranceivers except the NCX 1000 and the NCX-5 was the best I've owned. I found a copy of the external VFO, and it made the first rig a real nice setup. The mechanical dial is a marvel, right up there with Nixie tubes :), and pretty darned accurate as well. Not much else to add to the comments of others, but it is a pleasure to use with the NCL-2000.
W9MT Rating: 4/5 Jul 7, 2012 11:02 Send this review to a friend
Wistfully remember mine from the mid-1970's...  Time owned: more than 12 months
It was my first "real" 80-10m xcvr prior to going to a Heathkit SB-102 in the late 70's, a Drake C-Line in the 80's and solid state in the 1990's and forward.

Loved the mechanical digital readout. You could achieve sub 500Hz accuracy over a 500KHz band segment by opening the vfo housing and forking the finned segments of one of the tuning cap's rotor segments. This would non-linearly vary the mechanical change of the tuned capacitance very slightly as you cranked the vfo. This mechanical position non-linear change nicely cancelled any of the electrical design's capacitive tuning non-linearities. It was the next best thing to a Collins PTO. You just needed to make sure you didn't twist any fin enough to short to the adjacent stator plate. (Receive and transmit would disappear until you fixed that, but it didn't kill anything permanently.)

The Mk-II replaced the Mk-I's 7360 balanced modulator tube with a solid state BM. It was a big improvement. You really don't see any Mk-I's turning up on the used market anymore.

Most NCX-5's had a heat problem which would build up and drop your power output on 15 and especially 10m down to only about 80W carrier. You had to be using the radio with a lot of transmit over a number of hours of operating to notice this, though.

My unit used the 6GJ5 sweep tubes in its PA. I'm not sure if the pinout is the same as the 6JB6, but I do like the fact that 6JE6's can be substituted for the 6JB6 variants. TungSol and GE branded 6GJ5's lasted the best. RCA's would go soft very quickly. They'd still test strongly good in a tube tester and work in the rare TV that used them as the horizontal sweep amplifier, but they were no longer any good for amateur RF amp usage.

Notice the external vfo in eHam's photo. It's a rare item. I never owned one. Nice examples sell for what the hen's teeth Heathkit SB-640's do nowadays. It would leech power from the octal plug on the back of the transceiver and a coaxial output would feed from the external vfo thru the grommet on the cabinet back and feed an RCA jack at the internal vfo.

One could never find the 100KHz crystal calibrator on the used market. I cannibalized a Heathkit HD-20 chassis, put it in a minibox and used an octal pin plug on the box to connect it to the NCX-5. Simply rectify and filter heater voltage and the HD-20's circuitry runs quite happily, giving you 100KHz markers all the way up through the top of 10m.

The blue cabinet color was also quite pleasing from a Feng Shui standpoint.

Overall, a nice nostalgic rig, but more modern stuff blows it away.
W7CPA Rating: 4/5 Feb 14, 2010 05:23 Send this review to a friend
This Old Dog Still Hunts  Time owned: 3 to 6 months
I recently restored a 1967 vintage Nataional NCX-5 MKII and a NCL-2000. The receiver is suprising good when doing simple A-B weak signal comparisons with a FLEX-5000A, KWM2-A and TR-4CW RIT. I was quite suprised. The design had a few flaws but it has many positives features like styling and quasi accurate mechanical digital dial.
K7UA Rating: 5/5 Jan 15, 2009 13:27 Send this review to a friend
First digital readout I ever saw  Time owned: more than 12 months
Our county EOC had one of these in about 1970. I was the county ARES emergency coordinator. For a few years I got to use it during drills. It was incredible at the time to have a digital readout. As a struggling student I could have never afforded such a prize, but it sure was wonderful to use. It was a very fine rig during its time.
NY4O Rating: 5/5 Jan 10, 2008 04:10 Send this review to a friend
Great first rig!  Time owned: more than 12 months
I owned the NCX-5 in the mid-seventies (or as best I remember). It was my first rig as a novice, purchased used from one of the mail order Ham stores. I remember well the things pointed out by the previous reviewers as well as a few other items. First, the finals/matching network: I had no trouble with them. Due to misreading the HyGains poorly printed 18AVT instructions I connected the radials to the driven element. No problem (!) the NCX-5 loaded the ground rod and I made several contacts showing 599, as far away as Texas! My "Elmer" caught the error and the rig performance improved greatly.
Secondly: The rig had a tendency to "FM" the audio. I got several reports of bad audio. An on the air contact with expertise in "Nationals" told me that the wiper contacts on the main tuning capacitor were dirty. Contact cleaner and a contact file (extra fine sand paper) fixed the problem. I had to do this periodically while I had the rig.
Finally traded the rig about 1979 for a TenTec 544...what a difference! Still have the TenTec, wish I had the National too!
K7NG Rating: 4/5 Sep 26, 2002 01:57 Send this review to a friend
Nice rig for its' day  Time owned: more than 12 months
I had one of these in the 1975 - 1985 timeframe, with the NCXA supply/speaker unit. I carefully aligned mine when I got it since it had been sitting around for some time. (It was in like-new shape). I never had a gripe about its' performance or reliability - within its' limitations. It does require a fairly good match to the antenna or it may not tune up properly - and the sweep tube finals will get slagged if you ignore the proper tuning. I did the best I could with the VFO calibration, and without resetting via the optional crystal calibrator it's digital (mechanical wheels) readout would be within 2 KHz across any 500 KHz band segment. That's what originally intrigued me about the rig - the digital readout. It tickled me to be able to go to a sked freq and just zip over there with the dials clicking away...I eventually replaced the original 6JB6 sweep tube finals (same as Drake used in rigs of similar vintage) with 6LQ6/6JE6's which was no effort other than having to re-neutralize. Gave me a little more output if I wanted it (I didn't) and a BIG margin in plate dissipation which made operation into some of my more unwieldy antenna projects a little safer.
It was marginal on CW (no CW filters and klunky semi-VOX circuit controlling the TR changeover)but I made a heck of a lot of CW and SSB QSO's with it. I sold it to a ham I worked with, along with a Collins 75A4 I had and he may have it on the air to this day for all I know.
W4UDX Rating: 4/5 Apr 1, 2001 13:30 Send this review to a friend
Good for it's age  Time owned: 6 to 12 months
Surprisingly good performance. Easy to repair if it fails. Also easy to re-align. Mechanical digital readout is very accurate. Receiver lacks features but SSB filter is adequate to compensate. Only odd thing I noticed: T/R relay stays energized during receive, and de-energizes during transmit. This causes the relay to get magnetized after some extended use and then it hangs and acts up. I had the matching external VFO and PS/Speaker. The external VFO was also right on the money accurate. I received lots of compliments on my transmit audio using a Turner +2 desk mike. Sometimes I miss this radio. It was alot of fun
JAMES_BENEDICT_EX_N8FVJ Rating: 4/5 Dec 22, 2000 23:37 Send this review to a friend
Excellent  Time owned: 6 to 12 months
The National NCX-5 Mark II transceiver features 200 watts PEP SSB, 200 watts CW and 100 watts AM input on 80 thru 10 meters. The dial calibration resolution is 1 Khz with a mechanical digital readout. The tuning rate is 10 Khz per knob revolution and is identical on all bands. The receiver is a double conversion type with a xtal controlled HF oscillator on each band. The VFO is transistorized for high stability. The selectivity is obtained with an eight pole xtal lattice filter. The shape characteristic is 1.7 and at -60 db is only 4.76 Khz wide. The -6 db passband is 2.8 Khz for excellent SSB listening quality. The balanced modulator provides -50 db suppression, unwanted SSB suppression is -50 db and third order distortion products are -30 db down. The NCX-5 includes a 5 Khz RIT.
The NCX-5 is very selective and stable. The digital display is very accurate and frequencies are easy to find. The receiver does not drop off much in sensitivity on the 15 and 10 meter bands. The NCX-A AC input matching power supply is very rugged and heavy! I recommend this radio which is a 'cut above' the Tempo, Galaxy, Swan and others from the same era.

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