[Milsurplus] [RCA] SRR-13 Article, more

[Kenneth G. Gordon]

On 2 Aug 2016 at 16:58, antqradio at sbcglobal.net wrote:

> Ken
> My test was only for 6 hours with a modified power supply using the FRR-23 as a 
> test bed.  With 60 VA ac power input, the temperature reached and stabilized at 
> 107 degrees internally and the top of the case was just barely warm.  I can 
> imagine that a rack of stacked receivers with unmodified power supplies with 
> about 100 VA ac power input would be a bit different.

Well, I am not convinced that that is the only reason. But, as I said, it was a long time ago.
 
> I have made two sets of brackets so that the FRR-23 and the working SRR-13A 
> can be rack mounted.

I have a number of the original rack-mount adapters for these receivers. They are VERY 
heavy steel! I can send you a set if you would like to have them. At least you could use them 
as models. ;-)

>  This makes working on rhe receivers much easier than 
> struggling with a receiver that is table mounted.  One interesting problem that 
> popped up with the SRR-13A is that when in the case and rack mounted, it 
> started tripping the shop GFCI.  

Hmmmmm....not good....

> Since the GFCI only trips when the SRR-13A power switch is turned ON, 
> perhaps there is an issue with leakage in the power supply?

Well, as you know, there are very extensive filters in the back-plane of those receivers. I 
would suspect bypass capacitors right at the AC input. This is a common problem with 
R-390s for instance.

>  But the receiver 
> operates correctly on the bench with a direct connection for ac power to the rear 
> connector.  Anyway, using a constant voltage ferroresonant isolation transformer 
> cured the problem.  Now I have to investigate why there is a difference between 
> the SRR-13A and the  FRR-23 which does not have this particular issue.  Always 
> something to look into!

Oh, yes. This is what makes this stuff fun! :-)

> 
> I did notice that the back apron of the SRR-13A has one less BNC connector 
> then the FRR-23.  This extra BNC connector allows the FRR-23 to have a 
> remote First Oscillator.  I guess this is for the diversity setup that allows the LO of 
> one of the FRR-23 receivers to be slaved to the other.  While the SRR-13A is 
> also capable of diversity reception, each must evidently use independent local 
> oscillators.

Yes.

> More to come after I do some housekeeping in the shop!

Boy! Me too!!! :-(

Ken