[R-390] A vs non A

[Raymond Cote]

Now you all are going to have me checkup books again although I don't have my original lesson plans. I use to teach alignment and I remember a little about staggering for increased BW by setting the first of a little sly of 455 and the others on center and a little high. I wonder where this procedure
 originated. 

Randy!  Did you do any staggering on the tender?


Raymond Cote
1466 Townline Rd
Steward Ill 60553
808-341-8213
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Human beings are passionately attached to their beliefs by interests  
that have nothing to do with the truth. 

On Oct 14, 2012, at 23:38, "Charles P. Steinmetz" <charles_steinmetz at lavabit.com> wrote:

> Ed wrote:
> 
>> I also just finished looking through the R-390 manual to see what it 
>> said about alignment and confirmed there is no reference to 
>> sweeping.  To be fair, the description of transformer coupling to 
>> achieve the passband is correct, but unless there is a means to 
>> adjust the coupling then the best you can do is to align all at the 
>> center frequency, and sweeping won't make it any better.
>> 
>>     *     *     *
>> 
>>> The Alignment procedures are in TM 11-5820-357-35, 9 March 1962.
>>> This begins on page 91.
> 
> Peaking works to get the undercoupled stages on center frequency, but 
> not the overcoupled stages.  If you peak an overcoupled stage, you 
> will end up with one of its two peaks at the IF center frequency and 
> an asymmetrical overall response.  If I had to do this in an 
> emergency without sweep facilities, I'd try peaking the overcoupled 
> stages on a good strong broadband noise source like a noise diode 
> rather than at a single frequency, and I'd do those stages last, 
> after peaking the undercoupled stages.  It's been a long time since I 
> fiddled with a 390 IF, but ISTR there is one overcoupled stage.
> 
> Regarding the alignment procedures given in the 390 TMs, as I said in 
> my 10/9 post:
> 
>> Note that the IF alignment
>> procedures given in the TM-11-5820-357-35 (1962) and TM-11-856 (1955)
>> manuals do NOT stagger-tune the IFs -- if you read carefully, they
>> both state "Perform the procedure outlined . . . below only when the
>> transformer cores have been displaced greatly from their normal
>> positions within the cores."  In other words, "This procedure will
>> get you back on the air, but will not return the radio to its proper
>> IF alignment."
> 
> This is at TM-11-5820-357-35 p. 93 paragraph e(2) and TM-11-856 p. 
> 118 paragraph d(2).
> 
> So yes, there is a procedure given in the TMs to align 390 IFs.  But 
> the authors were clear that it was not a routine procedure.  Rather, 
> it was to be used "only when the transformer cores have been 
> displaced greatly from their normal positions within the cores" due 
> to damage or previous gross misalignment.  The reason, which the 
> authors clearly knew but did not see the need to explain, is that the 
> procedure given will not return the IF to its factory alignment 
> condition but could restore basic functionality.
> 
> Best regards,
> 
> Charles
> 
> 
> 
> 
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