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Discussion in 'Amateur Radio Amplifiers' started by VE6KBA, Mar 22, 2012.

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  1. VE6KBA

    VE6KBA Ham Member QRZ Page

    to all tech forum: my question , did anyone or anybody modified the tank circuit in NCL-2000 , i am tired of reparing and searching for the band swich for this amp . it is good design butt the weakest point is the band switch ,did anyone change design or finde solution for this cheep, weak, cheeze, miniature band switch in this amp , almost imposibile to find new one , it is the shame that National with such good design put in so small switch wich burn contacts soon you are out of proper resonance , i just wonder if is different solution (tecnical ) to this problem , perhaps to redisigne PI circuit, new coil different capacitor and stronger heavy duty switch , i would appriciate any info and help. thank you sincerely VE6KBA Kruno Bugar in Calgary Alberta Canada, please let me know at my e-mails or
  2. K0BG

    K0BG Platinum Subscriber QRZ Page

    The truth is, the NCL-2000 was not much more than a 6 on a 10 scale when it was brand new. The bias circuitry leaves a lot to be desired. If you try to use the amp on the WARC bands, you run the chance of not only arcing the band switch, but smoking the plate choke as well. And finding working 8122s is nearly impossible. Best relegate it to the Archive Shelf.
  3. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I think Carl KM1H was involved with that amp when he was with National, and might have a better bandswitch suggestion.

    I put my old NCL-2000 on six meters more than ten years ago and the bandswitch has never failed, since now it doesn't have one!:p:eek:

    While I was in there I changed the T-R relay arrangement also, and just went to a Dow Key coaxial double pole relay in lieu of the bus wires and open frame stuff that was in there, and modified the relay keying circuit to be 12V at 5 mA or so, so just about any transceiver in the world could key it.

    Other than that, it's worked and worked and worked and worked and worked.
  4. KM1H

    KM1H Ham Member QRZ Page

    The most common reason for switch failures is cockpit error. I have 4 and the switches are all original. They dont like high VSWR or half a**ed tuning that has knobs going in all directions. The switch is the same construction as most all similar power amps of that era and I get tired of people blaming the switch for their own ineptitude.

    If you cant learn to tune it then start with the manual settings, have someone set it up and write a tuning chart for you. Or fix the external problem that is causing the repeated failures.

    Of course the bias circuit works very well unless somebody does something stupid such as blowing out the screens and the big bang blows the transistors and zener. Germanium SS was all that we had back then to work with. There are under $3 modern substitutes available.

    The original design was idiot proofed with fault trips and screen regulator but the puke in the VP of Marketing office had it yanked due to cost.

    Another one here is a prototype Ive had since 64 and has been modified to cover 160 and WARC and the stock choke is OK on 17 but not 12. I used a B&W 802 when I did this in the 80's and ran it many years from the 60's in heavy contesting. It now loafs at a vintage SSB setup here with a HT32B and SX-115.

    Another prototype has been on 6M since I built it during several lunch hours in 1964 and I finally replaced the 1966 date code tubes 2 years ago when the power was down to 600-700W. A conversion to Svetlana 4CX400A's or a single 3CX800A7 isnt that difficult.

    Last edited: Mar 23, 2012
  5. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

  6. VE6KBA

    VE6KBA Ham Member QRZ Page

    to Mr. Alan K0BG thanks for suggestion , to be honest i was thinking same as you ,after time i owe this amp for allmost a year ,i could not use a few times , this is it , good show piece!!!!
    Last edited: Mar 23, 2012
  7. VE6KBA

    VE6KBA Ham Member QRZ Page

    to WB2WIK thank you for e-mail , when i got this amp allmost a year ago it was mint condition with new tubes , still it is . , in the first place was my fault for switch to burn , not knowing much about inspite reading manual from top to botom you still can make mistake and that was it one small error and swich was burnt , than i fix switch with changing contacts it was working good for a while untill i sold this amp but other guy did same error and amp comme back to me again , returning the money , so i have now white elephant in my shack,I newer think to modifie for 160 or 6 meter bands not much interess on those bands .eventualy i will finde new switch and than get rid of it for good , but anyway thank you so much for responding to my quest e-mail .sincerely K.B. VE6KBA
    Last edited: Mar 23, 2012
  8. VE6KBA

    VE6KBA Ham Member QRZ Page

    To Mr. Carl KM1H
    thank you for responding to my request, i understand you where involved with design of this amp at National and understandebly so you get iritated when somebody criticize design that product you work with; you,r right when you said problem start in cookpit & pilot but you have to admit that switch is weak link of entire amp, you can not belive that small tiny contacts on that swich can carry 1KW of RF energy,(i learn my trade in Radio industry where we build broadcasting transmiters & !KW transmiter is 50 times biger than this litle amp) even most seasoned radio operator can make mistake and it takes only a second and swich is gone, in design like that must be included some margin for error in design and size of components. 9remember amps from 5-10 years before this amp or military equipments) You mentioned yourself about cost cutting measures in company at that time , and band switch is another part of that. Anyway, one another gentelman on E-bay has whole bunch of NOS NCL-2000 spare parts,(Iassume he was working at National as well ) i will buy new swich and get rid of a problem amp.Thank you sincerely for your opinion and sugestions K.B. VE6KBA
  9. W9GB

    W9GB Ham Member QRZ Page

    Kruno -

    IF you are that concerned about the band switch, then why are you replacing it with the same OEM switch?

    The Kenwood TL-922 Amplifiers had a similar issue, BUT the Kenwood rotary switch was no longer available from Kenwood or the Japanese OEM supplier,
    SO the radio amateurs at Multi-Tech Industries adapted their "off the shelf" Model 80 Rotary Switch; P/N R802G1130003

    They have sold 32 of these replacement Kenwood TL-922 switches just on eBay, seller name: multi-tech-industries

    You can e-mail Multi-Tech Industries with your inquiry (if they can adapt an "off-shelf unit" to your National) at:
    BTW, such as part is ~ $180 USD. Quality costs $$.

    Multi-Tech Industries, Inc.
    P.O. Box 159, 64 South Main St.
    Marlboro, New Jersey 07746 USA
    Tel: (732) 431-0550
    Fax: (732) 409-6695

    ECONOMICS. Carl has already commented about National management .. and any engineer working for a North American company knows about the constant battle
    between the financial (cost accounting) and enough engineering ....

    Broadcast radio/TV industry is whole another animal from amateur radio.
    I grew up near the Gates/Harris broadcast equipment plant in Quincy, IL (building SW transmitters for African countries & broadcast O&O operations in NYC, Chicago and West Coast).

    Yes, high quality components are used with broadcast transmitters, but the AM/FM/SW/TV broadcasters of the 1950s - 1970s had big $$$ ..
    knew how to spend it .. and wanted high relibaility (~ 24 hour. 7 day week operation) to keep those advertising (revenue) $$ coming in the door.
    The maintenance windows at those stations were usually only 5 to 6 hours each week, between Sunday Midnight and Monday at Sunrise (or 6:00 AM).

    BTW, that industry rapidly changed in the mid-1970s to early 1980s .....
    Sony Walkman, Satellite TV channels, Home Video pulled that captured revenue market away!! Many Harris competitors left broadcast market or were acquired.
    Last edited: Mar 23, 2012
  10. KM1H

    KM1H Ham Member QRZ Page

    Its NOT an undersized switch for its use. The same size is in the SB-220, Clipperton L, all the AL-80 series and others...over 50 years of amp applications.

    If it keeps blowing its cockpit error or an external problem....period.

    Geting it away from you is a good thing and hopefully a new owner will enjoy it.

  11. VE6KBA

    VE6KBA Ham Member QRZ Page

    thanks to W9GB for sugestion ,i will do that!! contact MultiTech industrie for custom made switch , 73 and have great weekend K.B.
  12. VE6KBA

    VE6KBA Ham Member QRZ Page

    to KM1H , thanks Carl you are right , amp is mint cond. and I am not giving up that ease!!!when it works it is great amp. K.B.
  13. W9GB

    W9GB Ham Member QRZ Page

    K -

    IF you call by telephone, ask for "Skip" and tell him details about the switch.
    They MAY request that you ship the old switch to them -- for proper fit, and clearances.

  14. KM1H

    KM1H Ham Member QRZ Page

    Its Skip Coleman and be ready for sticker shock, Ive been dealing with him since the 80's when it was still Radio Switch Corporation. He will make anything you want thats based on one of their standard products and what you want is a Model 78.

    A cheaper alternative is the senior series Ameritron switch which still is expensive plus either one will have to be adapted. Both are clones of the old Centralab JV-9000 series (Electroswitch bought the Centralab ceramic switch division over 20 years ago) and is what I use in my modified NCL.

  15. W9GB

    W9GB Ham Member QRZ Page

    Quality parts are not cheap !


    That is ElectroSwitch's D9 series ??
    Provides up to 24 positions with a frame less than 3 inches

    2010 Yonkers Road
    Raleigh, NC 27604

    Telephone: (888) ROTARYS or (919) 833-0707
    Fax: (800) 909-9171 or (919) 833-8016
  16. W1QJ

    W1QJ Ham Member QRZ Page

    I always enjoy Carl's frankness :)
  17. VE6KBA

    VE6KBA Ham Member QRZ Page

    I wish to sincerely thank to all of you out there who helped me with your advises and sugestions to solve my problems with NCL-2000 , have great sunday and all the best to you and yours . K.B. VE6KBA
  18. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    I second that.
  19. KU3X

    KU3X Ham Member QRZ Page

    When I got my General ticket (1977) I purchased and NCL-2000. Being new in the hobby I knew I had to read the manual when I put that amp on line.
    I ran that amp for many years and .....other than taking a lightening hit that took out the tubes and power relay, I never had any issue with that amp.
    I replaced the tubes and power relay and it worked as good as new. I sold it to a friend of mine and he also never had an issue with amp.
    I always, and still do, use only resonant antennas. I never every heard a spark in that amp. I ran contests with that amp and was able to change bands on the amp in 20 seconds.
    The band switch may or may not be a weak link, but it never failed on my. It was a tame amp and did exactly what the manual said it would.

    The band switch must be able to carry a certian amout of current and voltage. If it does it without failing, it can't be that much of a weak link.
    Bottom line, if you run the NCL-2000 by the manual and use resonant antennas, you should not have any problems.
    Barry, KU3X
  20. AG6K

    AG6K Ham Member QRZ Page

     As I recall the bandswitch in the NCL-2000 has open contact (OC) spacing similar to the bandswitch in the SB-220. Since the 220's bandswitch has an OC breakdown potential of c. 4900v at sea-level, the bandswitch in a NCL-2000 should be more than adequate for HF RF since it has lower HV than the 220. However, VHF has more ability to arc than HF, so it's possible that your NCI-2000 had an intermittent VHF parasite. To find out, unsolder one end of each parasitic suppressor R and measure the ohms. If the resistance has increased more than 50% odds are that it had an intermittent parasitic oscillation. To reduce the ability for VHF oscillation, reduce the VHF-Q of the VHF suppressors. This will lower VHF amplification.
    - note - on my Web site there is a diagram that shows circuit improvements for the NCL-2000.
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