[R-390] Gear train rebuild..

[Craig]

Hi Pete,

No doubt, a gear train rebuild of a R-390/A is a test of one's mechanical aptitude. The current version of the Y2K R3 is a great document. Scott Seickel's "Gear Train Rebuld" in that version made the task easier for me.

Placing the parts in a logical order on a clean work bench while disassembling helps. An uninterrupted 12 hour work period for the rebuild should be set aside............plus several 6 packs of adult beverage.

Regards,
Craig  

-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Pete Williams
Sent: Wednesday, July 13, 2016 7:15 PM
To: r-390 at mailman.qth.net
Subject: [R-390] Gear train rebuild..

​A  couple of  tips from experience..... not  extensive but having relied
on the   Y2K-3  reference, thought this might be a useful  addendum
Also saves  a   great volume of cussing.
1. Before   reassembly set the Geneva drive to the  07 +007 position per
drawing in manual. Check the  wafer  contacts on the  band  switch to agree with the pics for the  7 Mhz  position.
2. Keeping the    8-16Mhz shaft in position  when  fitting the   other
gears is a pain.  I've  used a  small bolt ,washer  and  nut thru the cam hole at the  rear of the  RF  module  holds it in place for the duration and on its  mark.  ---Check tho'
3. Fitting the other  gears  while  maintaining the  2  tooth   stretch of
the  split gear also  a pain.  I do the 2 tooth  stretch  and use a  short
piece of fine   wire thru' and  around the  teeth and  twist to  hold the
alinement. Keep the clamps positioned  for  ease in  tightening  when doing the  final  check/cam setting. The wire  can be  cut off  at this time too.
4.Fitting  and mating the  gears while  tied  now is  much easier. Don't
tighten the  clamps on the   shafts but  just enough to  stop  gears
moving from their  adjacent  alinement  setting. Don't  try to  hold  the shafts  to their marks--- sort this  at the  end.
RF MODULE  ... T 204  4 - 8Mhz    antenna   xfmer/assy
With   a seeming increase in these  radios  and  assemblies  coming on the
scene, it would be  wise to  check that  front end  coil....  For  what
ever reason,  previous  users    either private , mil/navy managed to get
large   amounts of  RF  into the
 front  end.
The  most recent one  I  did  had the primary  fibre  former and  wire completely carbonised.  This  would make it the  4'th  I've  encountered over the years so  apparently  that  frequency  range the  most popular in high power  circles.
Thanks to  those  who  have gone this route before  and  authored   such a
fund of  knowledge.
Cheers
Pete  VK3IZ
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