[R-390] Cosmos Dis-assembly

[wa3frp at aol.com]

Hi Bob, 
Sorry that I was not clear.  The PTO works but now that I've removed a turn on the midpoint adjustment coil, the PTO tunes 1000 Hz in slightly less than 10 turns. So, I tried to turn the adjustment screw counterclockwise only to find that the core turns but is not coming back toward me as I face the screw slot in the coil from the front of the PTO.  In checking further, I see that I am turning the slug (why does this have to be slightly behind the transformer?) and with a light and some extra magnification, it looks to me that the screw is past the screw track or at least that it what it looks like to me. So, I figure the next step is to remove the midpoint adjustment coil by unsoldering the two attached wires and then backing off the locking nut and removing the entire coil to see if I can get a better look at what is happening and to see if I can get the screw back in the screw track. Except for this problem, the PTO is in excellent condition. Thanks and 73 Russ WA3FRP





-----Original Message-----
From: rbethman <rbethman at comcast.net>
To: R-390 Mailman <R-390 at Mailman.qth.net>
Cc: wa3frp at aol.com
Sent: Sun, Apr 18, 2010 2:14 pm
Subject: Re: [R-390] Cosmos Dis-assembly


Russ,

I'm confused!

How can you use the PTO if the slug is off its track?

It may be that the PTO was turned too far while NOT installed.

Please enlighten us.

And YES, I put US back on the group.  Group "wisdom" is better in the details than only one person!

This is where Roger "Flowertime" is extremely helpful!   

< I defer to THE Expert in the fine details! >

Bob - N0DGN

On 4/18/2010 2:08 PM, wa3frp at aol.com wrote: 

Hi Bob, Thanks for your message.  I've been inside, tried some adjustments but was not successful as the tuning slug looks to be damaged.  It appears to be off its track and too far down in the endpoint adjustment inductor. So, I've close things up and put my R-390A back in use temporarily. I need a nice solar flare, something that knocks the HF signals off the air for a few hours, so that I can go back in and unsolder the two leads on the endpoint adjustment inductor and see what it will take to get the variable inductor to vary. 
 
While things were opened, I did unscrew the cap to see what the screws looked like associated with linearizing the PTO.  They sure are tiny!  First things first. Once the endpoint adjustment has been completed, I do plan to take a look at linearization.
 
Thanks and 73
Russ WA3FRP 




-----Original Message-----
From: rbethman <rbethman at comcast.net>
To: r-390 at mailman.qth.net
Cc: wa3frp at aol.com
Sent: Sun, Apr 18, 2010 11:46 am
Subject: Re: [R-390] Cosmos Dis-assembly


Russ! 
 
Okay! Now the "original" post finally got the can off. 
 
Now - How is it going? 
 
Any reall issues with the endpoints? 
 
How about all the "intermediate" alignment screws? ( Yes - they ARE a pain! ) 
 
Don't worry about pressurizing it after you are done. BTW - it is an everyday schrader valve, just like on the car tires. 
 
Talk to us! 
 
Bob - N0DGN 




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