[R-390] Ultimate heresy answered

[Les Locklear]

If you were so worried about Dallas Lankford, perhaps you could have spelled 
his name correctly.

Les Locklear
Gulfport, Ms.
Professional Curmudgeon & Equal Opportunity Annoyer

----- Original Message ----- 
From: "Perry Sandeen" <sandeenpa at yahoo.com>
To: <aa9il at sbcglobal.net>
Cc: <r-390 at mailman.qth.net>
Sent: Monday, January 02, 2006 8:18 PM
Subject: [R-390] Ultimate heresy answered


> Wrote: The ultimate heresy? Has anyone attempted to completely rebuild the 
> modules or (entire?)
> R390 A radio with new low noise resistors, modern caps, wiring, etc.
>
>     Wrote: I to would like to know if anyone has done this, also add to 
> the list the trusty
> R388/URR.
>
> Mike & Ken; the short answer is kind of.
>
> I've been "hotroding" receivers for 50 years.  I started with a S20R. 
> I've done a ARR-15, several
> SP-600's as well as some R390's back in '65-'66 at Karamursel Air Station 
> in Turkey.
>
>     It is good science to replace all resistors and caps.  The low noise 
> metal film units are far
> quieter that any carbon comp type ever was, could be, or will be.  Modern 
> insulation  materials
> make the same true for capacitors. Teflon sub-miniature co-ax is manna 
> from heaven if you need to
> fix any receiver co-ax problems.  The 6DC6 can be replaced with a 7788 if 
> you want to put in a
> 9pin socket, re-bias and fiddle with the AGC.  This was the front end tube 
> that we used at
> Hallicrafters in the late 60's in special OTH receivers.
>
>     All BA's receivers will benefit from inrush current protected 
> electronically regulated power
> supplies.  This especially true of the R-388 and SP-600  which use PS's to 
> develop negative bias
> voltages and were designed for a lower nominal line voltage than most of 
> have today.  The noise
> filters on both the SP-600 and R-390 should both be replace with modern 
> low leakage units to avoid
> shock hazards.  R-338's can have much better audio.  0A2 regulator tubes 
> can be replaced with a
> six stack of TL431's for lower noise, better stability and at less expense 
> than using the 0A2.
>
> Sadly, your post will probably show the schizophrenic traits of a few 
> developmentally limited PC
> self-appointed ludites (from the Guardians of Art Society) who only write 
> to complain.  They will
> "allow" the idea of a resistor instead of a ballast tube, a new blocking 
> capacitor for the
> mechanical filters, the Langford AGC mod, accepting "GASP" solid state 
> rectifiers!  After that, it
> is almost total denial that R-390's can have major improvements other than 
> a product detector.
> And God help you if you propose mods with any new holes: torches will be 
> lighted.
>
>     Unfortunately, these vocal few have driven off the list Dr. Jerry and 
> Dallas Langford who
> have contributed to vast improvements for the R390 and R390A in particular 
> and other BA equipment
> in general.  Between them, they may have forgotten more about BA's than 
> most of us now
>
>    As soon as I can  I can get to them, my three R390A's, my three SP 
> 600's and three R388's will
> all work much better than when the rolled off the assembly line due to 
> replaced components and
> reworked circuits.  I have a Fluke 6080 signal generator, 200 MHz scope, 
> audio distortion analyze,
> audio power meter, and VTVM's  to calibrate and verify what I have 
> improved.
>
>     After stage one it's off to dual gate fet's for the IF, SS temp 
> regulated ovens and LMxxx
> series solid state audio outputs.
>
> Bon Voyage,  Perrier
>
>
>
>
>
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>
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