[Fwd: Re: [Drake] T-4XB LSB Problem]

[Tony Sokol]

-------- Original Message --------
Subject: 	Re: [Drake] T-4XB LSB Problem
Date: 	Mon, 21 Feb 2005 18:05:23 -0600
From: 	Tony Sokol <tonysokol at sbcglobal.net>
To: 	drake at mailman.qth.net
References: 	<3rr9ri$nev96n at mxip18a.cluster1.charter.net>



Hi Larry,
    Well, it looks like it's time for a call to ICM.  Here is what I get:

SSB Mode:  5642.1 to 5644.3
CW Mode:  5.643.1 to 5645.0

I have been trying to find some information on the crystal filter center 
frequencies but so far no luck.  From this I am assuming that the 
frequency needs to go ABOVE 5654.0 to get centered in the LSB filter.  
Does sound like the way to go?

Thanks
   73
Tony

PS:  Do you have a source for the Greenish Blue filter material.  I saw 
the ones advertised on some web sites however they sure look pretty 
Blue...or is that what they were supposed to look like?



ltaft at charter.net wrote:

>Tony,
>
>Try listening with an accurate receiver to the 5645 osc and check the range of tuning of C2.  It should be approximately equal +/- around 5645.  I've repaired some 
>T-4XB sets with bad 5645 xtals.  If the osc is covering the range then it sounds like you have a bad filter. 
>
>I use a spectrum analyzer to check the filters and the overall operation of the Drakes I repair.  The sideband filters are like children....each one has its own set of lumps and bumps but if the slope edges cross at the carrier freq and the insertion loss difference isn't more than a few db then they will work fine.  
>
>The T-4XB IF system inverts the signal so if the front switch says LSB then the actual filter is a USB ie, above the IF carrier freq of 5645. I may also have a good filter for the actual USB position I can sell you.  I'll have to dig in the boneyard to see what it is.  
>
>73, Larry  K2LT
>drakerepair.com
>800-687-9161
>  
>
>>From: Tony Sokol <tonysokol at sbcglobal.net>
>>Date: 2005/02/20 Sun AM 01:51:01 GMT
>>To: drake at mailman.qth.net
>>Subject: [Drake] T-4XB LSB Problem
>>
>>Hi Gang,
>>    I just acquired a nice R-4B and T-4XB pair and have spent most of 
>>the weekend cleaning and aligning.  The R-4 is coming out pretty nice 
>>however the T-4XB seems to have a problem with much lower output on 
>>LSB.  I tried performing the "Carrier Oscillator, Filter Match & 
>>Balanced Modulator" adjustment procedure with out much luck.  It takes 
>>many turns to get the balanced modulator to unbalance much at all.  I 
>>get a very small amount of carrier unbalancing R4 (carrier balance) and 
>>when I switch to LSB I get nothing adjusting C2 as suggested.  I can 
>>adjust C2 to get quit a bit of carrier in LSB while in the TUNE position 
>>but I don't think I am really balancing the filters in this position.  
>>In fact, when I do this I can whistle up output on both sidebands but 
>>again, LSB is quite a bit lower.  Tuning in the USB position I can get 
>>around 120 watts or better on all bands except 10 where it's around 100. 
>>    I hope this sounds familiar to someone and I am also hoping that it 
>>isn't pointing to a bad LSB filter.  If it is, then I guess I am going 
>>to have to find a source for one.  I hope I am just be overlooking 
>>something simple in my haste to get these two cleaned up and on the 
>>air.  Any thoughts on the subject?
>>
>>    Thanks
>>Tony - W9JXN
>>
>>
>>
>>
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>>
>>    
>>
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