[R-390] Help with info on a STRANGE SP-600

[Sheldon Daitch]

Let me mention two other methods of diversity...

Frequency - using two (or more frequencies), not
  generally practical at HF, but can be done, provided
  the transmitters are at the same site and use the
  same "programming" audio.  One application that
  we used was for our WWV monitor, one RX was
  on 15 MHZ, the other on either 5 or 10 Mhz, so
  we did not have to worry re day or night time
  propagation.  Frequency diversity is really useful
  at microwave frequencies.

  We also used audio frequency diversity on HF RTTY
  with the Northern Radio tone units, using a high set
  of AFSK tones and low set of AFSK tones, in the
  audio channel, and the tone demodulators had a
  voting methodology to determine mark or space,
  if the two channels did not agree.  If I remember
  correctly, it was level driven.  (Remember,
  selective fading in the audio channel.)

Time - Generally related to data.  Barry Research
  had some RTTY products which used 7 tone channels
  for the same RTTY data, only each channel was
  shifted in time slightly on transmit, and the matching
  modem, reshifted them in time, and used a voting
  methodology to decide if it was a mark or space,
  depending on number of channels indicating that
  "time" item was a mark or space.  This way a static
  burst would take out different data bits, because of
  the time shifts.  This BR stuff was fairly high dollar
  gear, I think.

73
Sheldon
WA4MZZ

Michael Murphy wrote:

> Bob,
>
> Concerning Diversity operation at HF, R390A, SP600 or otherwise, you have
> the right idea. Using two different types of antennas should work OK.
>
> There are three ways to use Diversity at HF.
>
> 1. Simple Space Diversity - Here we need two identical antennas, that is the
> same polarization, gain, and arrival angle. These could be a couple of
> dipoles at 100 feet. They should be spaced out several wavelenths apart (!!)
> however for diversity to really work.
>
> 2. Polarization Diversity - This setup purposely uses two different kinds of
> antennas, like what you were suggesting, a Carolina Windom and an inverted
> L. The antennas should not have drastically different gains, or the system
> will not "vote" properly. Better choices might be a Marconi vertical or
> sloper dipole and a regular dipole.
>
> 3. Arrival angle Diversity - Requires the use of a receiving antenna with
> discrimination in the vertical plane. For this reason it does not appear to
> be a method that is in common use for HF. With a vertically steerable array
> comprising short vertical monopole or active loops, worthwhile improvements
> are possible by isolating the different ionospheric mode and using them in
> diversity.
>
> This was from a paper
> http://murray.newcastle.edu.au/users/staff/eemf/ELEC351/SProjects/Fitzsummon
> s/elec352.htm
> Composed by:
> Troy Morris
> Jay Fitzsummons
> Tony Parezanovic of Newcastle College
>
> Mike WB2UID
>
> ----- Original Message -----
> From: "John KA1XC" <tetrode at comcast.net>
> To: "R-390 reflector" <r-390 at mailman.qth.net>
> Sent: Tuesday, July 20, 2004 11:06 AM
> Subject: Re: [R-390] Help with info on a STRANGE SP-600
>
> > Bob,
> >  check out the Hammarlund Historian page (is that Les ?), there's a
> > paragraph about the R-450/FRR-28 towards the bottom.
> > http://www.hammarlund.info/sp600.html
> >
> > BTW looks like removing the ncr from the file name in the 3d link fixed
> it.
> >
> > 73 ,
> > John
> >
> >
> > ----- Original Message -----
> > From: "Rbethman" <rbethman at comcast.net>
> > To: <R-390 at mailman.qth.net>
> > Sent: Tuesday, July 20, 2004 9:46 AM
> > Subject: [R-390] Help with info on a STRANGE SP-600
> >
> >
> > > Fixed the THIRD link.  Have NO bloody idea why it didn't work.
> > >
> > > What's worse - I'm a computer freak!
> > >
> > > Try now.
> > >
> > > Bob
> > >
> > > Gang,
> > >
> > >     I've acquired a "peculiar" Hammarlund SP-600.
> > >
> > >     It is a Model J-11, s/n 9758. [No "X"]
> > >
> > >    Modified by Northern Radio Company for the Diversity Aspects.  NRC
> > > Type 159, Model I, S/N 740.
> > >
> > >    Tagged Receiver, Radio R-450/FRR-28.
> > >
> > >         <http://home.comcast.net/~rbethman/sp600j11front.JPG>
> > >         <http://home.comcast.net/~rbethman/sp600j11rear.jpg>
> > >         <http://home.comcast.net/~rbethman/sp600j11data.jpg>
> > >         <http://home.comcast.net/~rbethman/sp600j11.jpg>
> > >
> > > Bob - N0DGN
> >
> >
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