"New" SWAN 500CX and CLIPPERTON L, together.Please help.

Discussion in 'Amateur Radio Amplifiers' started by K2JPV, Sep 13, 2014.

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  1. K2JPV

    K2JPV XML Subscriber QRZ Page

    I have been lucky to get these two like new beauties. The 500 has been gone over by the Swan Dr, and she is really nice,no probs..I Just got the Dentron,orig tubes..looks very low hrs on orig tubes. I would Like to use these two oldies together( I know i would have to drive the swan lower pwr) but what about the connections? keying grid currents? etc ? With all the experience out here Im expecting to learn alot here...be gentile ,THANK YOU ALL IN ADVANCE.
    Clipperton L serial number 99..and Swan 500 CX..Compatable ?
     
  2. W9GB

    W9GB Ham Member QRZ Page

    John -

    WATCH the Difference in RF INPUT and RF Output Specifications.
    DIVIDE the RF INPUT numbers by 2 (50% efficiency) for approximate RF Output.

    This usage of RF INPUT, in the manuals,
    was due to changes in FCC requirements and specifications, since 1960s.

    The Swan's RF drive would have to be "cut back" (~ 70-100 watts RF OUTPUT) for the Dentron Clipperton "L".

    Swan 500CX Operations and Maintenance Manual
    http://bama.edebris.com/download/swan/500cx/swan500.pdf

    The Swan 500CX using two 6LQ6 sweep-tubes in PA provides this RF INPUT:
    550 watts P.E.P. on SSB
    325 watts on C.W.
    125 watts on AM

    Dentron Clipperton L, using four 572-B tubes provides RF INPUT ~ 2 kW P.E.P on SSB; 1 kW on CW.

    Dentron Clipperton "L" Manual
    http://www.n4brf.org/PDF/Dentron Clippertom L Manual.pdf

    W2XC notes
    http://www.w2xc.com/Clipperton_Notes.htm

    ===
     
    Last edited: Sep 13, 2014
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Re the 500CX power ratings, those are actually "DC input" numbers, not RF output ratings. It can't run 550W PEP output from a pair of sweep tubes, and the power supply (117XC) can't deliver enough current for that.

    Its actual output power is in the 250W PEP range on SSB and about 175-200W on CW. If "tuned up" too long, the tubes fail and output drops down very quickly.

    I think these two are compatible, generally. The 500CX can definitely overdrive the Clipperton-L, though. When using such a pair together, it used to be pretty common for guys to add a 3 dB 50W resistive attenuator inside the Clipperton to reduce the drive (I know I did that, even driving it with a TR-4 which also ran a bit too much drive for the amp).

    The pad also improves the input match by 3 dB, which is a good thing and helps the transceiver achieve better IMD.

    The Swan relay can key the Clipperton-L directly so no outboard buffers are needed.
     
  4. K2JPV

    K2JPV XML Subscriber QRZ Page

    Thank you both. Tubes in the Swan now are peaking 330 easy speach ssb now. Not going work hard for little gain. Another 600w for what? Havin a blast with Swan solo. Will use the Clipperton w my icom 735 out at the desert qth..no more 100w "qrp" . 73's all.
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    330W out on SSB, I think you're overdriving the PA (sweep tubes). Unfortunately, the Swan doesn't monitor PA grid current or anything useful to indicate that.:p

    The 6LQ6 PA tubes are rated 30W plate dissipation each. Continuous output should be ~4x that (120W), PEP about 8x that (240W) for reasonable tube life (based on two tubes).

    The 500CX includes a transmit ALC circuit but it's difficult to tell just by looking at meter readings if it's actually working properly. It is supposed to limit cathode current to 225 mA, which at 800V B+ would only be 180Wdc input power (see manual, Page 11, "voice transmission"). That's where the rig operates "most cleanly" and is really neighbor-friendly. They warn about not using too much microphone gain and trying to drive that up higher. I'd follow that advice.:eek:

    But it's a cool rig. I used to be a Swan service/warranty repair center in NJ back in the early 1970s and had "factory training" in Oceanside on that rig as well as the 250C, 350C, 350D, 500C, 700CX, 600T, 600R, etc. It was fun.
     
  6. AF6LJ

    AF6LJ Ham Member QRZ Page

    I love my Swan 350, Full Contact Amateur Radio at it's finest. (or close to it.)
    :)
     
  7. KM1H

    KM1H Ham Member QRZ Page

    The L doesnt monitor grid current either.

    Altho 200W drive wont normally hurt the four 572B's it will likely blow the power transformer and possibly the bandswitch. Dentron said 150W maximum but that would be only for SSB without a compressor. AND run a fan on the transformer.
    Considering that 75W will drive a pair of as new tubes to full power, then 150W isnt out of line for 4 of them. Much more just gets passed thru.

    Carl
     
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