Upgrading an MFJ-962 III 1.5 KW Antenna Tuner

1. Since the 90s I have owned a Yaesu FC-301 antenna tuner as a backup. At that time I was using a homemade T-match, made by another ham, consisting of kilowatt rated GE roller inductor and variable capacitors. The winds of change caused me to sell the T-match and store the FC-301. Have been back on HF for a few months now, and realize how much I miss that homebrew tuner.
   
   
   
2. The Yaesu FC-301 is a high quality parts and construction unit rated at 500 Watts, 160-10M.
   
   
   
3. But the design was really meant to be a station accessory for the Yaesu FT-301 transceiver, and did not quite "fit" with my newer radio, a Kenwood TS-850S.
   
   
   
4. Yearning the tuning action "feel" of a continuously variable control as opposed to the fixed switch of the FC-301 tapped inductor, I looked around eBay for a suitable roller inductor and got one for $53. It did not have a turns counter but I thought I would deal with it later as a project began to take shape.
   
   
   
5. Finally, I saw an older but reasonably priced MFJ 962 Versa Tuner III, rated at 1.5 Kw PEP, and although banged up a bit, it looked like a good candidate for a tuner upgrade project. Including shipping and tax, it came to $133.
   
   
   
6. These are pics from the eBay auction. I noticed a previous owner had already drilled holes on the front panel (I was going to do the same so what the heck!).
   
   
   
7. Once received, I proceeded to remove the tapped inductor and ceramic switch.
   
   
   
8. Here are the pieces for the transplant. Maybe I should have been a surgeon.
   
   
   
9. Fiddling with the new parts to find a good spot.
   
   
   
10. Deciding that using a multifunction single needle meter was a thing of the past, I entertained the idea of using dual meters from a CB SWR meter (hoping other hams would never see this).
    
    
    
11. Now we open the frontal cranial cavity so we can use the electric drill to make additional holes for the inductor shaft.
    
    
    
12. And PRESTO! We have installed the new inductor.
    
    
    
13. Since we do not have a turns counter (yet), copper sleeves were fashioned and installed at the end of the roller wheel to restrict travel at the ends. It actually works better than expected. If the roller wheel jumps out, it will remount by simply reversing the turning. We also installed flat copper strips for ground and other connections to reduce stray inductance and improve the overall RF path.
    
    
    
14. For now we hold the original meter with tape to conduct initial tests. The tuner worked. Turning the roller inductor for maximum noise was music to my ears (Ok, static is not classical music but am a ham).
    
    
    
15. After some deliberation, decided not to use the CB SWR meter (phew!) and looked for a suitable dual meter. It turns out that a Diamond SX-40C VHF unit was being auctioned on eBay and got it for $30.
    
    
    
16. The SX-40C meter was designed for VHF/UHF use and it had a "monimatch" RF sampler that dropped off sharply on 160 and 80M. It was not made for that low frequency. We had to do some reverse engineering and figure out how to use the new meter movement with the original Bruene Bridge the MFJ 962 came with.
    
    
    
17. Surprisingly, I had two needed additional adjustment potentiometers and a DPDT switch to replace the old multifunction one.
    
    
    
    
    
18. Had to fabricate holding brackets for the new meter. An old aluminum baking tray came in handy.
    
    
    
19. OK, so we had to whip out the electric drill again and make holes for the new meter switch holding hardware.
    
    
    
20. Also took out a can of spray paint to obscure the unused labels on the meter switch and the inductor position switch.
    
    
    
    
    
21. New dual needle meter detail.
    
    
    
22. The old "CAL" control is no longer of use because the dual needle meter does away with this adjustment so for now I taped a sign over the empty control hole.
    
    
    
23. We do still have extra holes from days past but is there a war wagon without bullet holes?