[time-nuts] Sayrosa 607B Frequency Synthesizer

GandalfG8 at aol.com GandalfG8 at aol.com
Sun Nov 25 15:31:48 UTC 2012


Hi Mike
 
I haven't seen too many of these in the wild so can I  assume this was the 
unit recently sold on Ebay?
 
If so you got an excellent drive unit at a very good price, even if it  
isn't working at the moment:-)
 
FCO standard equipment with these was the HCD-1519 1MHz frequency  
reference and whilst they are specified to run from 1, 5, or  10MHz I've not run 
them from anything else so not sure offhand whether  these frequencies are 
automatically accepted, which I suspect they were, or  whether internal 
selection is required but I should be able to check on  that.
 
As you suggest, the output is inhibited whilst the fault indicator is  
illuminated.
Is there a number showing on the display to go with your "Fault"  
indication, and are any other of the indicators illuminated?
 
It's possible a link may be required on one of the rear  connectors to 
enable stand alone operation but again I can't remember offhand so  will check 
and come back to you on that too, but there shouldn't be any  significant 
wiring needed.
 
Like much equipment from that era though these units suffered the dreaded  
tantalum capacitor disease and it's quite possible that one or more modules 
may  be afflicted.
 
First thing to check is the power supply.
 
There are 5 separate supply rails with two each of plus and minus  12 Volts 
and one of plus 5 Volts, each using an appropriate 78xx or 79xx  regulator. 
If any are at zero this obviously indicates a possible failure but  also 
perhaps a shorted supply line so this needs to be checked.
Whatever the results here you though you should still check each  of the 
internal modules.
 
Where the supply rails attach to the circuit boards in the modules the  
first component in most, if not all cases, is a small series inductor which is  
followed by a 10uF tantalum capacitor to ground. If this or another 
capacitor  has failed short circuit, which is the common failure mode, it could 
either be  pulling the rail down or it's possible that the inductor will have 
burnt  out which will restore the external supply but leaving part at least 
of the  module non functional.
 
If this does turn out to be the case and proper replacements aren't to hand 
 a short term fix, although not recommended in the longer term, is to use  
standard electrolytics for the caps and wire links to replace the  inductors.
 
Good luck:-)
 
Regards
 
Nigel
GM8PZR
 
 
In a message dated 25/11/2012 09:39:11 GMT Standard Time,  
mike.millen.uk at gmail.com writes:

This  unit is a part of the UK's Diplomatic Wireless Service's "Piccolo" HF 
RTTY  network.

I have acquired one of these & am trying to get it  working. 
It accepts a 10MHz (or 1 or 5) reference & the output can be  set to any 
frequency between 3MHz & 29,999,900Hz, in 100Hz  steps.

My unit is showing a "Fault" LED on the display, which I believe  is 
inhibiting the output. I can see a varying frequency at the o/p socket, but  only 
a few mV, not the 1v into 50R as is normal.

I suspect that the  fault indication is because there's nothing plugged 
into either the "Keying  Frequency Control Input" nor the "Carrier Frequency 
Control Input"  sockets.  (There's also a "V.F. Inputs" & "Carrier Output 
(BCD)"  sockets.)

Can anyone help with a manual or connection details for the 2  input 
sockets, please?

Many  thanks,
Mike
M0MLM
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