I'm the proud owner of a nice SP-600, unfortunately it is without tags, can
someone help me to identify wich version I have?
Here below some details:
-Non-mil radio no yellow anti-fungus varnish at all;

-Disc capacitors, no black beauty;

-The antenna connector looks to have been factory modified to an SO-239
style to accept coax cable;

-Crystal deck with crystals

-Dial lock

-Gray front panel, white letters engraved.



thank you



Claudio

"moreradio" wrote in message
.. .
I'm the proud owner of a nice SP-600, unfortunately it is
without tags, can someone help me to identify wich version
I have?
Here below some details:
-Non-mil radio no yellow anti-fungus varnish at all;

-Disc capacitors, no black beauty;

-The antenna connector looks to have been factory modified
to an SO-239 style to accept coax cable;

-Crystal deck with crystals

-Dial lock

-Gray front panel, white letters engraved.



thank you



Claudio

This is not enough information. There is a great deal
of information on the web, do a Google search for sp 600 jx
to find it.
There were more than twenty variations of the SP-600
made, most nearly alike. The total production was on the
order of 25,000 units. Your description fits most of the
receivers with exception of the VLF special, the JX-17 (has
two extra switches and three small red knobs) and those made
without the fixed frequency crystal unit. All have very
similar circuitry.
The receivers should have a name plate on top of the
tuning capacitor cover with serial number and version type
on it. These are somtimes missing.
The disc capacitors were used in receivers built after
the mid fifties but a great many earlier receivers built
with Sprague Black Beauty caps were modified due to the very
high early failure rate of these caps. Also many receivers
were modified to have the SO-239 connector rather than the
balanced coax connector originally used. All of the JX-17s
had these from the factory.
I am pretty sure the anti-fungus treatment was applied
after market and not all receivers have it. Actually this is
an advantage if you have to work on the thing because the
anti-fungus is very difficult to get off and often glues
things together.
At least one of the web sites has a list of versions
although its not quite complete.



--
Richard Knoppow
Los Angeles
WB6KBL

"Richard Knoppow" wrote in message
m...

"moreradio" wrote in message
.. .
I'm the proud owner of a nice SP-600, unfortunately it is without tags,
can someone help me to identify wich version I have?
Here below some details:
-Non-mil radio no yellow anti-fungus varnish at all;

-Disc capacitors, no black beauty;

-The antenna connector looks to have been factory modified to an SO-239
style to accept coax cable;

-Crystal deck with crystals

-Dial lock

-Gray front panel, white letters engraved.



thank you



Claudio

This is not enough information. There is a great deal of information
on the web, do a Google search for sp 600 jx to find it.
There were more than twenty variations of the SP-600 made, most nearly
alike. The total production was on the order of 25,000 units. Your
description fits most of the receivers with exception of the VLF special,
the JX-17 (has two extra switches and three small red knobs) and those
made without the fixed frequency crystal unit. All have very similar
circuitry.
The receivers should have a name plate on top of the tuning capacitor
cover with serial number and version type on it. These are somtimes
missing.
The disc capacitors were used in receivers built after the mid fifties
but a great many earlier receivers built with Sprague Black Beauty caps
were modified due to the very high early failure rate of these caps. Also
many receivers were modified to have the SO-239 connector rather than the
balanced coax connector originally used. All of the JX-17s had these from
the factory.
I am pretty sure the anti-fungus treatment was applied after market
and not all receivers have it. Actually this is an advantage if you have
to work on the thing because the anti-fungus is very difficult to get off
and often glues things together.
At least one of the web sites has a list of versions although its not
quite complete.



--
Richard Knoppow
Los Angeles
WB6KBL


FWIW;
I have an SP600 with the JX17 designation on the the tuner cover.
It has the balanced coax antenna connector, and coverage from 540 kHz
to 54 mHz, and no red knobs. Of course, there's always the chance
of a swap of tuner covers...
Nelson

"Nelson" wrote in message
...

"Richard Knoppow" wrote in
message
m...

"moreradio" wrote in message
.. .
I'm the proud owner of a nice SP-600, unfortunately it
is without tags, can someone help me to identify wich
version I have?
Here below some details:
-Non-mil radio no yellow anti-fungus varnish at all;

-Disc capacitors, no black beauty;

-The antenna connector looks to have been factory
modified to an SO-239 style to accept coax cable;

-Crystal deck with crystals

-Dial lock

-Gray front panel, white letters engraved.



thank you



Claudio

This is not enough information. There is a great deal
of information on the web, do a Google search for sp 600
jx to find it.
There were more than twenty variations of the SP-600
made, most nearly alike. The total production was on the
order of 25,000 units. Your description fits most of the
receivers with exception of the VLF special, the JX-17
(has two extra switches and three small red knobs) and
those made without the fixed frequency crystal unit. All
have very similar circuitry.
The receivers should have a name plate on top of the
tuning capacitor cover with serial number and version
type on it. These are somtimes missing.
The disc capacitors were used in receivers built
after the mid fifties but a great many earlier receivers
built with Sprague Black Beauty caps were modified due to
the very high early failure rate of these caps. Also many
receivers were modified to have the SO-239 connector
rather than the balanced coax connector originally used.
All of the JX-17s had these from the factory.
I am pretty sure the anti-fungus treatment was
applied after market and not all receivers have it.
Actually this is an advantage if you have to work on the
thing because the anti-fungus is very difficult to get
off and often glues things together.
At least one of the web sites has a list of versions
although its not quite complete.



--
Richard Knoppow
Los Angeles
WB6KBL


FWIW;
I have an SP600 with the JX17 designation on the the
tuner cover.
It has the balanced coax antenna connector, and coverage
from 540 kHz
to 54 mHz, and no red knobs. Of course, there's always
the chance
of a swap of tuner covers...
Nelson

The JX-17 was intended for diversity operation and has
connectors for the IFO (second conversion oscillator) with a
switch on the front and the BFO, also with a switch and aso
a connector on the fixed frequency assembly to use an
external HFO. This has an additional position on the
crystal-VFO switch. It has some other minor changes to the
circuitry: a different BFO circuit and fixed crystal
circuit, and the BFO injection level is fixed so it does not
have the injection pot on the back. These receivers were
made with the coaxial antenna connector rather than the
balanced connector used on other models, however many
receivers were modified to use the coax connector. Its not a
difficult mod but requires a lot of work.
Evidently, a lot of receivers were modified for
diversity reception with unsatisfactory results so
Hammarlund decided to offer a factory version. Most JXs,
however have means for more simple diversity work, namely an
IF output and access to the AVC and Detector lines.
If you want very high quality audio connect an
external amplifier to the detector terminals (needs a DC
blocking capacitor and is rather high impedance). The
detector itself has quite low distortion. However, note that
the normal AVC time constant is so fast that the level will
vary with low frequency modulation. The cure is to run it in
manual RF gain or to hang a rather large cap (a couple of
microfarads) across the AVC terminal on the back. This is
why the RF level meter bounces with modulation, it is
measuring carrier level.
A last note: The SP-600 is a very good receiver but I
think a lot of them are working but sick. The freqency
calibration and RF tracking should be very good but I think
the mechanical alignment of the tuning capacitor drifts with
time so a lot of them are not longer properly aligned. The
stators are held onto the frame with three clamp screws. The
stators should be exactly parallel to the rotor and exactly
centered. Also vertical alignment should be exact with the
edges of the rotor and stator plates in line when the cap is
closed. NEVER bend plates. Even though the end plates are
slotted they were never meant to be adjustable that way.
Once they are bent it is extremely difficult to ever get
them straight again and the stress will eventually break the
plates off the shaft.
Proper mechanical alignment requires removing the
tuning cap. This is a lot of work but not really difficult.


--
Richard Knoppow
Los Angeles
WB6KBL

In om on Sun, 1 Nov
2009 15:08:24 -0800, in rec.radio.amateur.boatanchors, 'Richard Knoppow'
wrote:

The JX-17 was intended for diversity operation and has
connectors for the IFO (second conversion oscillator)

Just out of interest, how long has diversity encoding been around? I
thought of it as relatively modern, and I've only read about it from the
POV of digital signals. Is there anywhere anyone'd recommend for a bit of
research? Something semi chronological would be nice.

Dave J

On Sat, 7 Nov 2009, Dave J. wrote:

In om on Sun, 1 Nov
2009 15:08:24 -0800, in rec.radio.amateur.boatanchors, 'Richard Knoppow'
wrote:

The JX-17 was intended for diversity operation and has
connectors for the IFO (second conversion oscillator)

Just out of interest, how long has diversity encoding been around? I
thought of it as relatively modern, and I've only read about it from the
POV of digital signals. Is there anywhere anyone'd recommend for a bit of
research? Something semi chronological would be nice.


It goes back to the thirties, at least. Hallicrafters had a diversity
receiver back then, I have no idea how many were sold.

There was an article in "Ham Radio" decades ago about diversity and
specifically about that Hallicrafters radio. Looking at an accumulated
index, I think it was the April 1980 issue. But, there was a history of
Hallicrafters in the same issue, and that one (from the same accumulated
index) is supposed to be in the Nov 1979 issue, which makes more sense
since for a long time the magazine devoted the November issue to
receivers.

Michael VE2BVW

Dave J. wrote:

Just out of interest, how long has diversity encoding been around? I
thought of it as relatively modern, and I've only read about it from the
POV of digital signals. Is there anywhere anyone'd recommend for a bit of
research? Something semi chronological would be nice.

Back to the thirties at least. Earlier diversity systems were comparatively
crude, though, normally just looking at two antenna systems separated in
space or in polarization and picking the one with the higher AGC voltage.
This can give a remarkable improvement in dealing with ionospheric fading,
though. Was standard practice for remote shortwave links on broadcast
networks.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Scott Dorsey" wrote in message
...
Dave J. wrote:

Just out of interest, how long has diversity encoding been
around? I
thought of it as relatively modern, and I've only read
about it from the
POV of digital signals. Is there anywhere anyone'd
recommend for a bit of
research? Something semi chronological would be nice.

Back to the thirties at least. Earlier diversity systems
were comparatively
crude, though, normally just looking at two antenna
systems separated in
space or in polarization and picking the one with the
higher AGC voltage.
This can give a remarkable improvement in dealing with
ionospheric fading,
though. Was standard practice for remote shortwave links
on broadcast
networks.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Space diversity is indeed that old but there were some
fairly sophisticated methods such as the Bell Labs MUSA
Multiple Unit Steerable Antenna which could be varied in
vertical angle electrically. RCA was using triple space
diversity receiving systems at the Riverhead N.Y. receiving
station in the 1930s. I suspect one could find a lot of
literature in the old Jornal of the IRE and probably also
the Bell Labs Technical Journal and RCA Review although I
don't have specific citations.
Around the 1950s Leonard Kahn and others worked out
means of combining the sidbands of a conventional AM or
double sideband suppressed carrier signal using a
synchronous detector. In effect this was a sort of frequency
diversity. It also reduced distortion due to selective
fading since it regenerated the carrier locally.

--
Richard Knoppow
Los Angeles
WB6KBL

On Sat, 7 Nov 2009, Richard Knoppow wrote:

Around the 1950s Leonard Kahn and others worked out
means of combining the sidbands of a conventional AM or
double sideband suppressed carrier signal using a
synchronous detector. In effect this was a sort of frequency
diversity. It also reduced distortion due to selective
fading since it regenerated the carrier locally.

Wasn't it Webb at GE that was doing the work on DSB? That's the name on
the synchronous detector article in "CQ" in the late fifties, and that was
either preceeded or followed by an article about DSBsc in general.

And John Costas of course came up with the Costas Loop for receiving AM,
and I see he was at GE in the fifties when he came up with the Loop.


Michael VE2BVW

Diversity is certainly not a new concept. It was present in the RCA AR88
designed about 1938-9!


"Dave J." wrote in message
...
In om on Sun, 1 Nov
2009 15:08:24 -0800, in rec.radio.amateur.boatanchors, 'Richard Knoppow'
wrote:

The JX-17 was intended for diversity operation and has
connectors for the IFO (second conversion oscillator)

Just out of interest, how long has diversity encoding been around? I
thought of it as relatively modern, and I've only read about it from the
POV of digital signals. Is there anywhere anyone'd recommend for a bit of
research? Something semi chronological would be nice.

Dave J