[Moon-Net] FT-736R how to adjust 23cm frequency?

Laurent REINHARD laurent.reinhard at free.fr
Thu Nov 24 18:09:06 CET 2016


Hello Dirk, 
i confirm the idea of Curt. 
on the FT736, there is an "master clock" of 20.480 MHz 
This clock is delivered to any modules for drive the PLLs 
this lock is located on TX UNIT F2887102 and the distribution buffer is located on AF UNIT F2887103 

You can found any informations at page 53 of technical support PDF 

The signal 28.480 MHz is REF 


Hope to help you 
73 
Laurent F4GEV 


----- Mail original -----

De: "Curt" <radio.ku8l at gmail.com> 
À: moon-net at mailman.pe1itr.com 
Envoyé: Jeudi 24 Novembre 2016 16:17:21 
Objet: Re: [Moon-Net] FT-736R how to adjust 23cm frequency? 

Heloo Dirk: 

I have not done this on my 736 but have spent some time refurbing a 1.2 
Module. So don't take this as the last word, but my impressions only. 

I don't think there are any oscillators on the module. It gets LO input 
from off-board and uses that as input for its own PLL. There is a VCO 
but it will track the input. 

There is complete data on this module in the tech supplement that 
includes alignment info---other than setting the VCO levels, there is no 
"master" frequency adjustment. You may have to go thru a complete PLL 
alignment to figure out what is going on. Are you sure there are no 
RIT/XIT values being input that could cause that offset? Doesn't seem 
reasonable that a PLL controlled system could be stable and off that 
much on only one band unless the 1.2G PLL is malfunctioning in an 
unusual way. 

The Fox Tango site, among others has the technical suppllement. 

Hopefully other users will chime in here. 

KU8L 

Curt 

On 11/23/2016 3:20 PM, Dirk Reyners wrote: 
> Hi Group, 
> 
> This evening we tried to calibrate my FT736R on 23cm, the frequency is 
> 2,6KHz off. (if you watch the pictures we set 1296.300 and counter says 
> 1296.2974 
> 
> Very annoying in E.M.E.... 
> 
> The 144MHz and 432MHz transmitters are +/- a few Hz bang on frequency. 
> 
> I opened the optional 23cm module to find out which screw to turn but, 
> nope... no result 
> 
> these are photos from the module 
> 
> https://photos.google.com/photo/AF1QipOFOI3ghJ1kRXI8DoS1_qWZOSO5yigafyAirmlW 
> 
> https://photos.google.com/photo/AF1QipME0uD3er7_4qPN8_Emlgz2eFcE2HV5QbNp2xiw 
> 
> https://photos.google.com/photo/AF1QipPNDynDquUoT7_mUN2XRI2z0Y8BjCR9LplAINZO 
> 
> http://www.foxtango.org/ft-library/FT-Library/Eighties/FT-736R_Tech_supp.pdf 
> 
> anyone done this before? 
> 
> I tried Q14, nope 
> 
> TC01 caused a fast frequency drift of 300KHz downward so quickly put it back 
> 
> Would be soooo nice to have my rig on frequency 
> 
> Best 73! ON5GS Dirk 
> 
> 
> 
> _______________________________________________ 
> Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html 
> 

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