[Central-Electronics] 100V AF phase shifter

[Russ WQ3X]

The modules are easy to work on. You can just pull one out a night (in your 
spare time!)  Inspect for broken or cold solder joints or just suck out and 
redo all the joints with wires going down to the plug at the base. I bent 
the wires 90 degrees after putting them thru the board to make a better 
mechanical connection to the pads instead of just sticking the wire in the 
hole like they did originally. I used small ty-wraps to nearby components to 
reduce pull on the joints. Also resolder the plug ends. I like to use liquid 
rosin flux for this (sticky and messy) but I make sure the pins are washed 
off well with alcohol and dried when done. I'm sure you will find some bad 
connections. Find some heavy plastic or thin blank PC board material and use 
it as an insulator against the can to prevent shorting when reassembling. 
Try it out after each module is done to see if you've improved things or 
possibly made it worse.

Russ


----- Original Message ----- 
From: "K6JEK" <k6jek at comcast.net>
To: <central-electronics at mailman.qth.net>
Sent: Sunday, December 03, 2006 12:42 PM
Subject: Re: [Central-Electronics] 100V AF phase shifter


> Great stuff.   I intend to follow everyone's advice and look for simpler 
> solutions first.   I replaced the mod caps when I first resurrected this 
> long abandoned 100V.  I doubt they are the problem.   Who knows?   Maybe I 
> just need to tweak a couple of pots.    Or maybe it will be at the other 
> end of the spectrum like Russ's and I'll have to take apart the cans and 
> look for weird little things.
>
> Thanks, everyone, for the suggestions.
>
> Jon, K6JEK
>
>
> On Dec 3, 2006, at 9:16 AM, Russ WQ3X wrote:
>
>> Most of the time the components are fine. The biggest problem on my own 
>> 100V was broken solder joints where the stiff wires from the socket plugs 
>> connect to the single-sided PC boards inside the module cans. Also there 
>> can be shorting of the PC board solder-side component leads to the metal 
>> can bodies. I found 11 different problems all because of this stuff on my 
>> 100V when I got it causing poor unwanted sideband suppression. This was 
>> in addition to an unsoldered joint from the factory on the mode switch. 
>> The previous owner had paid well over $1000 to have this unit "restored". 
>> Evidently the cans had never been taken apart by this expert. It was a 
>> mess in there and sure didn't work!
>>
>> I would not worry all that much about the .1% accuracy. Chances are the 
>> component is either fried or not, and normal ham test equipment should 
>> find the problem if any exists.
>>
>> I use a 2-tone generator and spectrum analyzer to check and adjust 
>> sideband suppression. (It came with the 100V when I got it and turned out 
>> to be very useful!)
>>
>> 73, Russ WQ3X
>>
>>
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