[R-390] A vs non A

[djed1 at aol.com]

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.  I've tried sweeping my Hammarlund, which does recommend sweeping the crystal filter.  I found that it wasn't much different than aligning by ear. 
Speaking of Hammarlund- they incorporated variable coupling to provide an effective variable IF bandwidth, so the technology was known in 1936.

Ed  W2EMN

 

 

 

-----Original Message-----
From: rbethman <rbethman at comcast.net>
To: r-390 <r-390 at mailman.qth.net>
Sent: Sun, Oct 14, 2012 9:57 am
Subject: Re: [R-390] A vs non A


The Alignment procedures are in TM 11-5820-357-35, 9 March 1962.

This begins on page 91.

Test equipment utilized/specified:

Electronic Voltmeter TS-505*/U.
Signal Generator AN/URM-25(*)
Voltmeter, Meter ME-30(*)/U
Insulated Alignment tool.

Note that *NO* sweep generator is specified NOR used.

So the whole Sweep Generator methodology is exactly as Roger states.

Following the U.S. Army procedures will not screw up your R-390.

N0DGN

On 10/11/2012 12:14 PM, Roger Ruszkowski wrote:
>   
> R390 IF's are no more complex than the R390/A
> Either can be done very well with a simple signal generator and volt meter.
>   
> The Sweep generator myth is in with moster gold plated Audio cable.
> Can I sell you some old bridge stock? I have original paper certificates.
>   
>   

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