1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Browning MKll 180

Discussion in 'Amplifiers' started by 238, Feb 15, 2020 at 12:40 AM.

  1. 238

    238 New Member

    Joined:
    May 20, 2019
    Messages:
    35
    Likes Received:
    2
    i need to know about the little trimmer by the relay. I have read, i think, it is the grid adjustment not sure. Also have been told it was for the input. Need to know the correct way to adjust. 238


     

  2. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    3,220
    Likes Received:
    3,327
    In theory, you put a SWR meter and coax jumper between the radio and the input jack of the amplifier.

    Key the radio and amplifier, tune for best modulated power.

    Now set the SWR meter's calibrate side and switch to read SWR.

    The trimmer should reduce the reading, but won't get it very low in my experience.

    The 180 was designed to use with tube-type radios that don't care too much about SWR when driving an amplifier.

    This post shows a rebuild, including a small coil we add to the input trimmer cap. Serves to bring the input-side SWR better than the trimmer can do it alone.

    https://www.worldwidedx.com/threads/browning-180-linear-back-from-the-funeral-pyre.238820/

    That's the short version.

    73
     
  3. 238

    238 New Member

    Joined:
    May 20, 2019
    Messages:
    35
    Likes Received:
    2
    DSC00810.JPG DSC00812.JPG DSC00809.JPG DSC00813.JPG DSC00810.JPG DSC00812.JPG DSC00809.JPG DSC00813.JPG Thanks a lot.I have had so much trouble finding info on a MKll 180. So i included pics of mine. The only things that look to be changed are the caps & it has 6KV6 tubes. All the resisters check ok. Could not check the two 1M resisters, i changed them. Can you buy new carbon resisters or are they all NOS? Thanks again. 238
     
  4. 238

    238 New Member

    Joined:
    May 20, 2019
    Messages:
    35
    Likes Received:
    2
    Well i hooked it up and with meter between my 2340 & amp it would peg the meter, Tuning the did not change anything. Trimmer might be bad. 238
     
  5. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    3,220
    Likes Received:
    3,327
    Don't know how long those two 450-Volt filter caps will last. Original parts were rated at 500 Volts.

    Years ago had trouble with using 450 Volt-rated parts, failing prematurely. Been using 500-Volt types ever since.

    The input-tune trimmer might be bad, but the circuit they used is the real culprit.

    I'll see if I can find some pics that will do a better job of explaining how we add the coil to that input circuit to get the input SWR below 2 to 1.

    73
     
  6. 238

    238 New Member

    Joined:
    May 20, 2019
    Messages:
    35
    Likes Received:
    2
    I am going to order some 500 volts caps. When i go back in to it i will change them & the diodes. 238
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!