[R-390] R390-A/URR Cam alignment. A question

[billriches]

-----Original Message-----
From: billriches [mailto:bill.riches at verizon.net] 
Sent: Monday, January 19, 2015 9:01 AM
To: 'Pierfrancesco Mengacci'; 'R-390 at mailman.qth.net'
Subject: RE: [R-390] R390-A/URR Cam alignment. A question

H Franco,

Your first if cam setting is correct - bottom only on #11 and #22 at 500
khz.  When you start alignment if you only get one peak on variable
capacitors on variable rf and if coils the mica caps in the coils have
changed value and must be replaced. It is a common problem with Stewart
Warner RF decks - not much of a problem with EAC decks.  

73,

Bill, WA2DVU
Cape May, NJ

-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of
Pierfrancesco Mengacci
Sent: Monday, January 19, 2015 6:13 AM
To: R-390 at mailman.qth.net
Subject: [R-390] R390-A/URR Cam alignment. A question

Dear Sirs!

I enjoyed the impressive manual "The 21st Century R390-A/URR Technical
Reference" but I can't catch the authors!

My Problem:

Did anyone notice that, in the section dealing with cams alignment
(paragraph 6.2.5.2 point 5, revision 9 of the manual), it is not specified
at which of the 32 bands the receiver must be set to check that "the cam
follower on first variable IF Z213 is near the valley of the cam when
Kilocycle Change indicates 500 Kcl"?

In my R390-A/URR (a Stewart-Warner make) the cam follower on rear cam of
17.5-25 Mc IF reaches the valley,  for a 500 Kcl reading,  only if I select
the bands 11 and 22.      IS IT NORMAL ???

I have not yet aligned my receiver, sensitivity is poor. 

Mechanical synchronization is perfect, I think, with the only exemption of
the rear cam of the above IF (in all the front cams, the reference lines
bisect exactly the cams ref. holes (at 07 +000)   and, in addition,
crystals & range coils selectors are correctly switching at required
positions.  PTO frequency and range are OK, also  (3.455 Kcl at 000 odometer
reading   and 2.455 Kcl at +000)..

 

Can you kindly help me and tell me if the above  circumstance is relevant,
before I proceed in electrical tuning?

 

Dear salutations, 

Franco Mengacci

Via XX Settembre 33 

15121 Alessandria, ITALY

 

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