Metal roof sections are usually fastened together to the roof structure with sheet metal screws.  If you could possibly fabricate a custom steele base plate.... with perhaps considerable spread at the base for stability,  and having legs with holes that would line up with pre-existing roof screws,  you might be able to put up a 10 or 20 foot aluminum mast perhaps.

Ed   K7AAT

  I'm glad to see Tisha above mentioned the possibility of inductive pickup on the antenna line from the overhead power lines.   While I don't think 950 feet would provide a hazardous potential,  it would be interesting to know what measured AC voltage would be at the end of that antenna.

  Ed   K7AAT

  There is a rather inexpensive ultra-sound device with small parabolic dish available for tracking down such power pole issues you describe as cracked insulator and hardware arcing.  They advertise occasionally either in QST or CW magazine.   

  Or you could build your own:  http://www.arrl.org/power-line

  or     http://www.midnightscience.com/ultrasonics.html

  or     http://www.exergia.info/books/analog_nonlinear/hanson.pdf

  Ed   K7AAT

  A picture of the radio and head would probably help me here,  but almost certainly that white lead from the control head is the ignition sense lead.  You can either hook it to the battery plus terminal for an always on condition,  or hook it to an ignition switched hot connection so that it goes off when you turn the car off.

  Ed   K7AAT

  In strict accordance to your question,  I would have to say that the MFJ 12W SSB  single band radios would likely be one of the easiest to repair.

   There are probably other companies marketing simple HF Xcvr kits which you might look for.  Anything you build yourself should be considerably easier to diagnose and repair.
Ed   K7AAT

   What you need is here: 

    http://www.k7mem.150m.com/Electronic_Notebook/antennas/shortant.html

   Ed   K7AAT

  Despite the numerous suggestions already posted here,  I believe your best bet for alignment tool source is:  http://www.gcelectronics.com/      On the Left click on Tools,  then select  Alignment Tools.

  Ed    K7AAT

  Don't understand your question, fully.   Why are you changing anything regarding your TV antenna?  Leave it alone.   Add a length of 50 ohm coax from your room to the J Pole....  RG213 or RG-8 would be best ... lowest loss,  but if your length is 50' or less it probably doesn't matter is you were to use RG8X,  which you did not list as a choice.   RG-58 is NOT recommended .... quite lossy.   don't forget the cost of appropriate connectors .... and an adapter for the coax connector at your station end to allow it to connect to your HT.   Good luck and have fun.

 Ed   K7AAT

  Please go back up and read Richard, K4KRW's response  ( #7 )  .   His is by far the most accurate and pertinent to this problem.   

   I have certainly been guilty to the social blunder which he clearly explains.   I do try to make sure no one is left out,  but sometimes it happens for the reasons he states.

   Best solution is to get to know the hams you speak to better.   Personal visits help a LOT.  They put a face to an otherwise unknown callsign .

   Good luck.

   Ed   K7AAT

They were the first thing that popped up on Google when I searched. 

Ed

  KB3KWJ is correct.  There is a "soldered in" memory battery in the FT757GX and it is probably dead.  The preferable replacement method would be to get a new battery from Yaesu  ( if still available )  and remove the old one.    The 'tabs' on those batteries are spot welded on.  I had not heard before of KB3KWJ's  suggestion of prying those spot welded tabs off the old battery and simply re soldering them to a new one, but it might be easier since otherwise you would have to remove the PC board to access the bottom to unsolder the old battery.

  Regarding your second problem,  this rings a dim bell .... I seem to recall VFO mechanism failures in some Yaesu radios in the past....  I would be strongly hesitant to put any kind of lubricant on that shaft .... I don't think it would help the problem, and it might make things worse if the lubricant worked its way into the opto-isolator tuning mechanism at the end of the shaft.  The best thing would be to replace the mechanism.... but may not be possible, or parts may no longer be available.   If I were you I'd Google and search for this specific problem in the FT-757.... there might be better help available out there on this specific issue.

  Good Luck  That's a nice radio ... I had one for several years long ago.

  Ed   K7AAT

  One more thing, Ron.  Bear in mind that due to the extremely weak beginning of this sunspot cycle,  propagation at the higher frequencies such as 10M tend to be lousy at present.   Don't expect to hear a lot of stations .... much of the time.

  But when things DO pick up, you might also consider 6M SSB ....   if your radio covers that.  Just replace your 10M whip with a   ~  55 "  whip.   Hurry up and upgrade, too !

  73
  Ed   K7AAT

  Which is it?    Your first post stated you were on a "quiet site " ... " with no desense ".   Now you claim there are numerous other radio sites in the vicinity.   

   Considering this new information,  I would not find it odd at all that you are getting poor audio on weak signals .  I surely would not blame it on the Kenwood  TKR-750.  Good luck in dealing with the RFI.

  Ed   K7AAT

  Yes, Jim,  that should work fine.   I assume you realize that you can feed both Inverted V antennas with the same coax ..... just solder or connect per your plan  both antennas to the coax.   The non resonant one will have negligible effect on the one you would be transmitting on.  You might consider running the two antennas perpendicular to each other,  but I don't believe it is very important that you do so.

Ed   K7AAT

  I am surprised you are having difficulty with receive on weak signals.  Our TKR-750 is superb...  brand new it measured around .23uV basic receiver sensitivity @12dB Sinad.   We added an Advanced Receiver Research  20dB gain low noise pre-amp to the front end and had to pad half the gain out to keep sensitivity above .10 uV.  I did not want to subject the front end to potential overload.   The copy-ability on extremely weak signals is outstanding.  No distortion what so ever. . .  and our TKR-850 performs every bit as well as the 2M repeater.  I would take those reports you hear about distorted weak signals with a grain of salt.   Every TKR-750 I've worked with has been excellent.   Apparently you have a problem which should be addressed before you pursue other work on that station.  Sorry I can't help you with that.  Good luck.

Ed   K7AAT