[R-390] R-390A and the SP-600

Fri Jan 12 16:04:50 EST 2018

Hi Tim, Bob, others.

I had several inquires once I fixed the misunderstanding that this is paper
and not film!
Anyway, I brushed the document off and started looking through it again
after many years collecting dust.

I have been working on an active tuning preselector and there is an
excellent treatment of broadband varactor tuned networks which is worth
posting. That said, I think I will look at the cost of scanning the
document or just scan it myself and send a pdf to the 390a reflector. Not
sure how large a file it would be, but certainly much less than a Y2K
manual! Alan

On Fri, Jan 12, 2018 at 12:19 PM, Tim Holzheimer <timholz59 at hotmail.com>
wrote:

> Alan
>
> I would like a copy of the RADC-TR-67-216 document.
>
> Let me know.
>
> Thank you.
>
> Tim Holzheimer
>
> 73 de N6DIY
>
>
> ------------------------------
> *From:* r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> on
> behalf of Alan Victor <amvictor at ncsu.edu>
> *Sent:* Thursday, January 11, 2018 2:47 PM
> *To:* Tisha Hayes
> *Cc:* R390A
> *Subject:* Re: [R-390] R-390A and the SP-600
>
> If any interest prior to the land fill or other Earth friendly paths.
> .
> I have an excellent copy from microfiche from the Rome Air Force
> Development Center
>
> *Preferred-circuit Techniques for Receiver Applications*
> Over 1000 pages Tech report no. RADC-TR-67-216.
> Date June 1967.
>
> Covers every conceivable circuit technique at the time for wideband
> receiver techniques; 1 MHz-10 GHz.
>
> Any interest, email me direct. 73' Alan
>
> On Sat, Jan 6, 2018 at 7:16 PM, Tisha Hayes <tisha.hayes at gmail.com> wrote:
>
> > I have had a chance to compare "a few" receivers. Presently I own;
> >
> > R-390A (three of them so there is some general opinions)
> > R-390
> > R-392
> > SP-200
> > HQ-129
> > SP-600 (JX17)
> > RF-590A (Harris)
> > R-3030 (Cubic)
> > CDR-3250 (Cubic)
> > RA-6790 (Racal, four of them)
> > WJ-8718 (Watkins Johnson)
> > 5650 (Telefunken, three of them)
> >
> > - It may seem like "a bunch" of radios but that is just the premium
> stuff.
> > I have a tendency to chase after perfection. (it may seem weird but I am
> > for-real, ask Perry, he knows me personally). Here is my opinion on the
> > Hammarlund family in comparison to the R-390A;
> >
> > The SP-600 was a fantastic radio that came out when AM and CW were king
> > around 1951. The design is reminiscent of the pinnacle of "knob turner"
> > radios and is a pleasure to use for SWL or BCB-DX listening. The JX17 is
> > really not the "best model" of the receiver, it was designed to support
> > diversity pairing with another radio and some changes in the circuitry
> and
> > voltages were made. If the crystal filter is close to the IF frequency it
> > can be a decent radio but often the crystals have changed frequency or
> the
> > radio was mis-tuned somewhere along the line. It also has a big problem
> > with BBOD (black beauty of death) oil caps and the electrolytic (the cans
> > and the bathtubs) capacitors.
> >
> > I have tried a bunch of things on an SP-600. Taking B+ ripple down to the
> > single millivolt level with filtering changes, building the "Nuvistor
> first
> > RF" plug-in instead of a 6BA6 and fighting (the never ending) battle
> > against drive slippage between the frequency disk and the knob
> >
> > The SP-600 is "drifty" for the first few hours and it is definitely not
> > frequency stabilized but if you leave it on for a long night of listening
> > to SWL it is a pleasing radio to listen to. The sound is very full and
> > sometimes I just listen to AM-BCB at night for the background noise while
> > doing something else in the house. As has been said it is a pretty
> > "intuitive" radio except for the IF bandwidth that can be a little
> > confusing unless you read up on it first.
> >
> > -----------------------
> > The R-390A is almost a generation newer than the SP-600 and is meant to
> get
> > on a frequency and stay there. Probably more than a few people on this
> list
> > spent their times wearing green or tan, wearing boots and eating
> K-rations
> > while they maintained racks full of R-390's in RTTY service. It works
> great
> > for data, is not as deaf as the SP-600 at higher frequencies and can be
> > passably good with SSB with an external converter.
> >
> > The R-390A is not a knob spinner (we all know that) and I invested
> > significant time in to smoothing out the drive mechanisms, playing with
> > synthetic oils and tungsten disulphide to make it less straining on the
> > wrists. It has a better tube line-up in the RF deck and the advantages
> (and
> > disadvantages) of mechanical IF filters. I have added roofing filters
> > between the RF and the IF and rather than butchering the audio deck I
> just
> > pick off the audio and feed it in to the AUX input on a Telefunken 5650
> > receiver (fantastic audio quality).
> >
> > By itself the R-390A can be "tiring" to listen to all evening long. It
> has
> > a hard to describe "robotic" sound. One receiver does not have that
> effect
> > but it is a rare R-390A variant with ceramic filters in the IF.
> >
> > How I wish the R-390A had an SSB mode.. it might be another reason from
> > keeping me away from the Harris RF-590A that I have been increasingly
> using
> > for dial hunting to listen to the chatter on the geritol-net on 80
> meters.
> >
> > -----------------------
> > In the past six months or so I have been buried in Telefunken rebuilds
> and
> > while I read the postings on this list I do not contribute as much as in
> > the past.
> >
> > *Ms. Tisha Hayes*
> > *AA4HA*
> >
> > *Sr. Engineer, 4RF USA.*
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