[Milsurplus] AN/GRR-5 Power Supply Questions

[WA5CAB at cs.com]

Joe,

In a message dated 8/19/2006 7:44:19 PM Central Daylight Time, 
carolew at bellatlantic.net writes: 
>     Here are my questions:
> 
>     1. The high-voltage rectifer (V-102) is a CK1007. I understand that
> they are scare. Do people usually replace them with diodes? If so, what
> kind of diodes and how should I wire them? Will I need a dropping
> resistor? If so, any suggestions as to resistance and wattage?

Unless yours is bad (not common) or missing, I wouldn't worry about it.  They 
seldom fail.

> 
>     2. CR101 and CR-102 are the selenium rectifers. Are they normally
> replaced with diodes or bridge rectifiers? If so, what kind and how do I
> wire them? Will I need a dropping resistor? If so, what do you suggest
> on resistance and wattage?

As Richard already said, change these to silicon, mounted inside the power 
supply, not in the cabinet.  There's no need for an additional dropping 
resistor.  On the side of the power supply is a filament adjust pot and test jack.  
Before firing it up after you've changed the rectifiers, turn the pot to 
minimum, and then do the adjustment.

> 
>     3. E-101 and E-102 are the vibrators. Any suggestions as to where I
can get spares?

I have some of the HV vibrators but the filament vibrators are rare.

> 
>     4. C101, C110 and C111 are 1,200 mfd/15 WVDC caps used as filters.
> Can I use 2,200 mfd/50 WVDC? How about 1,000 mfd/50 WVDC?

If those are your choices, I'd try the 1,000's first.

> 
>     5. C104 through 108 and C115 are .047 mfd/200 WVDC hash filters. I
> don't see them on any of the pictures of the set. Are they inside the
> relay (K-101)? If not, where are they?

Maybe someone else knows the answer to that off the top of their head.  My 
entire set is temporarily over in my storage building.

> 
>     6. Are there any wrinkles, tips, mods, suggestions that I should
> know about when I tackle the power supply?
> 

The PP-308 is known for eating power transformers.  As Richard said, change 
the buffer capacitors and also check and probably change the filter capacitors. 
 I've also encountered a couple with bad loudspeakers, but I can't recall any 
preventive measure for this.

Robert Downs - Houston
<http://www.wa5cab.com> (Web Store)
MVPA 9480
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