Pages: [1]   Go Down

Author Topic: KWM-2 Tune Up Question  (Read 331 times)

W2JJV

  • Member
  • Posts: 158
KWM-2 Tune Up Question
« on: March 11, 2023, 03:30:14 PM »

When I go through the load and dip tune up I've noticed on my digital power meter that output starts to drop off slowly when I leave it in Lock mode for a few seconds (probably more than I should).  When I switch back give it a few seconds and switch it back it usually increases but again begins the drop off.  Is this due to tube or component heating, or should I be thinking about looking under the hood.  Grid current seems adequate and power output on 40 meters is between 95 and 100 watts across the band. 

Any advice would be appreciated.

David, W2JJV
Logged

VK6HP

  • Member
  • Posts: 1222
Re: KWM-2 Tune Up Question
« Reply #1 on: March 11, 2023, 08:09:07 PM »

David,

I would not be unduly worried if the transceiver is still giving full SSB output (and, of course, you don't want to be doing CW with a KWM-2). If it gets worse I'd first check the driver tube (by substitution), and the ~800 V and ~250 V supplies.  If you're using a 516F-2 it'd be worth looking at the rectifier tubes if there's much droop under load.  My 32S-3 transmitter is a little prone to the effect and, from past experience, it's most likely the driver tube past its prime.

73, Peter.
Logged

N8NK

  • Posts: 179
    • N8NK QRP
Re: KWM-2 Tune Up Question
« Reply #2 on: March 12, 2023, 09:34:39 AM »

Hi there..
Although not a KWM-2, my old Heathkit SB-101 has done this a couple times in the past, and each time, it was the driver tube checking out, as mentioned by Peter above. In my case, that tube is being run pretty hard, and hot.
For me, the resolution was to grant the old man his well-deserved retirement and to buy myself a Yaesu FTdx-3000 as my own retirement gift. lol. 'Problem' solved.
Be well..
Chuck, N8NK
Logged

W2JJV

  • Member
  • Posts: 158
Re: KWM-2 Tune Up Question
« Reply #3 on: March 12, 2023, 09:40:43 AM »

Thanks gentlemen, got a couple of 6CL6's on order to swap out.  Wish they weren't in the cage, be a bit easier but need to do a thorough inspection and clean up some switches so I'll wait till June when the weather here in Tucson will be conducive to staying inside.  Typically 100F+.  And BTW Chuck, the KWM-2A was my retirement gift to the OM!  The rig I lusted after in my teens!
« Last Edit: March 12, 2023, 09:57:01 AM by W2JJV »
Logged
Pages: [1]   Go Up