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Restoring a Maverick 250 9 Tube Linear Questions

This is the place to ask questions about linear amplifiers, or power supplies

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743
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Joined: Monday, 09 December 2013, 12:46 PM
Radio: President McKinley
Antenna: Imax 2000
Name: Richard McDonnell
Home Phone: 623-322-1976
Location: Sun City, Arizona
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Restoring a Maverick 250 9 Tube Linear Questions

Post by 743 » Thursday, 26 July 2018, 16:47 PM

I haven't been able to post anything for a couple years due to 2 back injuries then a broken hip, and the slow demise of my wife due to Alzheimer's. Lots of Maverick 250 Posts I looked at but didn't find answers I need. I purchased a new President McKinley and traded my old Magnum 1 for this working Maverick 250 that gave me near 700 watts PEP on CH 38 (I only work SSB, no AM) and SWR went from 1.2 to 2.5. My questions follow. 1: There is a toggle switch in the back that is marked BTL. Is this a switch for turning on/off an RF pre amp? 2: Schematic from CB Tricks shows an ML250 and a MGL250. Don't know what those are?? 3: Schematic shows a 12AQ5 as the antenna relay driver and does other major things but mine is a 6HG5 so I suspect someone did a mod to make it 6V. Would you agree? The 6HG5 would be a sub for a 6AQ5 if one exists. All I'm doing is replacing the electrolytics, the plate choke to which was attached a 4.7nF 3KV Z5U ceramic plate capacitor and I broke off one lead. Made by RMC it's about 1 inch dia. Found lots of the same 4.7nF/3KV caps but none were called plate capacitors. 3: Any ideas (yes it did check mouser and purchased a couple different mfgrs) but I think plate caps have special qualities to assure temperature is high enough so value doesn't change over time. Agree yes/no? Not going to replace the tubes. Had a KL-203P which gives me 100W PEP so for one more S unit I need 400W. Any other ideas I sure would wellcome! Thanks, 743 "The Old Desert Fox" (Just sittin here with my toes in the sand watching the rabbits chase the coyotes)! Not now, I live in AZ and it is way too hot.


Former W6LZZ
743, the "Old Desert Fox" Operator Rick in Phoenix, AZ
Galaxy DX2517
Ranger RCI-2980wx with added R150 Linear and Fan Kit (Driver for Sweet 16)
Uniden 980SSB
Yeasu FT-840
MW RSP-3000-12 (13V/200 Amp DC Supply)
Texas Star Sweet 16 With Fan Kit
Imax 2000 Vertical Antenna


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