[Milsurplus] questions re early Stabilized Master Oscillators

[David Ross]

Ray -

   The 18Z-3 & 18Z-4 are equivalent to early ARC-58s -  the May 1 1958 
18Z-4 manual shows the saturable reactor and has no newer schematics.  
See photo from that manual here:
<http://www.hypertools.com/70H-13.jpg>

   The 70H-13 PTO is the leftmost 40% of the schematic, in the dotted 
line box labeled MASTER OSCILLATOR.  SMO drive circuitry is shown to 
it's right.

   Yow a servo-driven variable cap to correct an SMO?!?!

73
Dave Ross    N7EPI



On 7/9/2010 12:10 PM, Ray Fantini wrote:
> My ARC-38A uses varacaps hung external of the PTO for tuning correction so they were around for a while also the regular ARC-38 used a small variable capacitor and a servo system driving a syncro motor for frequency correction of the SMO. I never ran across the satutrable reactor, can you point to a diagram online?
> Ray Fantini KA3EKH
>
> -----Original Message-----
> From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of David Ross
> Sent: Friday, July 09, 2010 1:53 PM
> To: milsurplus
> Subject: [Milsurplus] questions re early Stabilized Master Oscillators
>
>     Before varicaps came into common usage, Collins used saturable
> reactors to electrically adjust the frequency of PTOs in their
> Stabilized Master Oscillators, specifically in early ARC-58s&  TRC-75s&
> URC-32s.  (Similar function to a varicap in modern VCOs.)
>
>     I have never seen a Collins SMO that used a saturable reactor -  my
> guess is that as soon as varicaps became available, all SMOs with
> saturable reactors were removed from service and replaced by SMOs with
> varicaps.
>
> Question 1    -    Did Collins use saturable reactors in any other
> SMOs?  (that is, other than early ARC-58s&  TRC-75s&  URC-32s)
>
> Question 2    -    Did any other manufacturers use saturable reactors in
> SMOs or other PLLs?
>
> Dave Ross    N7EPI
>
>