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 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 Subscriber 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 Subscriber 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.

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