I ended up with this & it's separate power supply in a package deal,
couldn't buy what I wanted without taking it. It looks better than
average but doesn't have the original S-meter. Both are rack mount
units in cases with a heavy interconnecting cable, and they are heavy!
It covers 1.25 to 40 Mc in 5 bands. Both units have aluminum tags with
serial numbers and the Rx is stamped Type O with a 40,000 serial.
I've heard that they have terrific audio but with only a portion of BCB
it's a bummer.
I'd like to know a bit more about it and if they have any value as
collectors items or are they true boat anchors? Is it a BC-794 A or B
or a SP-210-SX or what? Why did they make the power supply so heavy?
Thanks

--

73
Hank WD5JFR

I own one. Has little collector value - they made too many. Certainly
a very good boatanchor receiver for AM - in a class with R390,
HRO50/60 IMHO. No product detector so not good for SSB without an add
in prod detector.

Terry
W8EJO

Hi Terry
Got any idea which model I might have? Back in the 50s when I was a kid
I would have given anything to have one. And I only saw one real one,
the rest were in pictures!

--

73
Hank WD5JFR
"Nomad" wrote in message
...
I own one. Has little collector value - they made too many. Certainly
a very good boatanchor receiver for AM - in a class with R390,
HRO50/60 IMHO. No product detector so not good for SSB without an add
in prod detector.

Terry
W8EJO

"Henry Kolesnik" wrote in
message ...
I ended up with this & it's separate power supply in a
package deal, couldn't buy what I wanted without taking it.
It looks better than average but doesn't have the original
S-meter. Both are rack mount units in cases with a heavy
interconnecting cable, and they are heavy! It covers 1.25
to 40 Mc in 5 bands. Both units have aluminum tags with
serial numbers and the Rx is stamped Type O with a 40,000
serial. I've heard that they have terrific audio but with
only a portion of BCB it's a bummer.
I'd like to know a bit more about it and if they have any
value as collectors items or are they true boat anchors?
Is it a BC-794 A or B or a SP-210-SX or what? Why did
they make the power supply so heavy?
Thanks

--

73
Hank WD5JFR


There were three versions of the SP-200/210 made and
offered as both civilian and military receivers. The
difference was mostly in the frequency range covered. The
ranges we
540 Khz to 20 Mhz, 1250 Mhz to 40 Mhz, and an LF version
where two of the bands covered 100 Khz to 200 Khz and 200 to
400 Khz plus 2.5 Mhz to 20 Mhz. The 100 to 400 Khz bands
were used for aircraft communication. This LF model is the
BC-779, the other ranges had other military designations
(which have now escaped me).

The standard model has resistors in the RF sections of
the broadcast band to broaden out the bandwidth and allow
for high fidelity reception. I think the BC-779 may have
also have these in the two LF bands. The 1250 Khz to 40 Mhz
model has shunt-fed RF sections rather than series fed to
narrow their bandwidth and improve image rejection
especially on the highest band. Other than these variations
in the RF sections the receivers are identical.

You may have the 25hz version of the power supply, it
has a huge power tranformer and is very heavy. It was
intended to work also on 50/60Hz power. Many parts of the
world had 25Hz power when these receivers were made (and
some still do).

These guys are not collector's items and were made by
the thousands. The version you have is the most desirable
one as a ham receiver. I think you are not missing much by
not having the broadcast band, most AM stations now use so
much processing that a wide band receiver will sound very
unpleasant.

I used a BC-779 (with 25 hz supply, ugh) as my station
receiver many years ago. I tried all sorts of modifications
to the RF stages but wound up restoring the original
circuits. They are bulletproof and the relatively high
receiver noise is of no concequence on the HF bands,
especially in the big city. The RX is, however, vulnerable
to voltage drift. I installed a voltage regulator for the HF
oscillator, otherwise the thing will change frequency as the
RF gain changes. With regulation its quite stable.
There is no temperature compensation in the Super-Pro
so for good stability it should be run continuously. When
that is done, and with voltage regulation, it is
surprizingly stable. Because the RX has three IF's and an
isolated and amplified AVC the skirt selectivity is quite
good and its possible to increase BFO injection without
upsetting the AVC. They are actually pretty good sideband
receivers.
Don't know if original meters are available. The
original is illuminated by a screw base lamp projecting into
the meter.
When these were made they were the best receivers
obtainable. One military handbook I have in storage
somewhere shows comparison charts of spurious responses for
several common military receivers c.1945. The Super Pro is
very clean showing essentially only one image response. In
comparison the SX-28 graph looks like a cornfield.
I have not worked on mine for a very long time but
probaby remember some hints and kinks if you ask. Actually,
I want to dig it out and put it back in service.
Another note: most of the military Super-Pros were rack
mount versions with a shrowd type covering. This is probably
good for shielding but has no ventillation so the chassis
gets very hot. I drilled perforations in mine, maybe a
mistake, but that was more than 40 years ago.
I eventually found a couple of table type rack cabinets
for the RX and PS. Because the PS is separate, unlike the
SP-600, both will fit into any standard table cabinet.
There are several downloadable manuals for all versions
on the web. BAMA is a good place to start but there are
higher res versions available elswhere.


--

--
Richard Knoppow
Los Angeles
WB6KBL

On Oct 22, 1:43*pm, "Henry Kolesnik"
wrote:
Hi Terry
Got any idea which model I might have? *Back in the 50s when I was a kid
I would have given anything to have one. *And I only saw one real one,
the rest were in pictures!

--

73
Hank WD5JFR"Nomad" wrote in message

...

I own one. Has little collector value - they made too many. Certainly
a very good boatanchor receiver for AM - in a class with R390,
HRO50/60 IMHO. No product detector so not good for SSB without an add
in prod detector.

Terry
W8EJO

See this site for model ID:
http://www.skywaves.ar88.net/commrx/...-Pro_Data.html
and
http://www.radiomuseum.org/forum/cro... ceivers.html

and this site for info:
http://www.skywaves.ar88.net/commrx/...Pro_SP-10.html

If you need a manual they are also available online.

On Wed, 22 Oct 2008 11:33:14 -0500, Henry Kolesnik wrote:

I ended up with this & it's separate power supply in a package deal,
couldn't buy what I wanted without taking it. It looks better than
average but doesn't have the original S-meter. Both are rack mount
units in cases with a heavy interconnecting cable, and they are heavy!
It covers 1.25 to 40 Mc in 5 bands. Both units have aluminum tags with
serial numbers and the Rx is stamped Type O with a 40,000 serial. I've
heard that they have terrific audio but with only a portion of BCB it's
a bummer.
I'd like to know a bit more about it and if they have any value as
collectors items or are they true boat anchors? Is it a BC-794 A or B
or a SP-210-SX or what? Why did they make the power supply so heavy?
Thanks

Yours should be a SP-210-SX or BC-794-B (1.25 - 40 MHz)

More info at:

http://www.roveroresearch.org/sp200/bc779.html

"PJR" wrote in message
news:XpmdncIb_cmzlJzUnZ2dnUVZ_rmdnZ2d@metrocastcab levision.com...
On Wed, 22 Oct 2008 11:33:14 -0500, Henry Kolesnik wrote:

I ended up with this & it's separate power supply in a
package deal,
couldn't buy what I wanted without taking it. It looks
better than
average but doesn't have the original S-meter. Both are
rack mount
units in cases with a heavy interconnecting cable, and
they are heavy!
It covers 1.25 to 40 Mc in 5 bands. Both units have
aluminum tags with
serial numbers and the Rx is stamped Type O with a
40,000 serial. I've
heard that they have terrific audio but with only a
portion of BCB it's
a bummer.
I'd like to know a bit more about it and if they have any
value as
collectors items or are they true boat anchors? Is it a
BC-794 A or B
or a SP-210-SX or what? Why did they make the power
supply so heavy?
Thanks

Yours should be a SP-210-SX or BC-794-B (1.25 - 40 MHz)

More info at:

http://www.roveroresearch.org/sp200/bc779.html

An interesting site. There were more military
variations on the Super-Pro than shown, for instance, there
was a modification that allowed the use of crystal control
for fixed frequency operation. The crystal unit was mounted
behind the main tuning dial with two knobs projecting above
the dial, one for crystal selection and the other for fine
tuning just as in the SP-600. These were evidently used in
diversity operation with two or three receivers being linked
together.
While most of the drift will be over in half an hour it
really takes many hours for the receiver to stablize,
perhaps 12 hours. They were meant for continuous operation
and will not drift much when so operated.
It has been a puzzle to me that Hammarlund did not use
voltage regulators for the later Super-Pro's not even the
SP-400, even though they did use them in the comtemporaneous
HQ-100 and had the knowledge. The HQ-and its later versions,
also had temperature compensation. Perhaps the temperature
compensation would have required too much redesign of the
very complex tuning unit but voltage regulation would have
required little and is easily applied to existing receivers.
Some of the war time receivers, notably the
Howard-built ones have some other variations, probably due
to shortage of parts. For instance toggle switches are used
for the BFO switch instead of a rotary switch. Makes no
difference to operation but doesn't look as nice.
One somewhat obscure effect of the high quality audio
circuit is that static and interference are less bothersom
because the audio circuit is not exagerating them with
distortion. Most tube communication receivers have very
simple, single-ended, pentode output stages with no
feedback. The are big time distortion producers. The
difference is easily heard in a direct comparison. For
instance, for a receiver like the SP-600 which has a
detector output listening to this output on a good quality
external amplifier in comparison to the receiver's own
amplifier is night and day. Its interesting that the
original ads for the SP-600, based on a developmental model,
indicate it had push-pull audio. I rather think that the
desire to put the entire receiver, including the power
supply, on a single chassis required some serious
compromises including dropping the push-pull circuit. The
two chassis arrangement of the older Super-Pro's allows room
for the quite large audio stage, comprising three tubes and
two rather large transformers.
Some other receivers of the time also had push-pull
amplifiers, notably the SX-28 and SX-32, SX-27, SX-36 and
the National NC-100, NC-200 and later versions, and the
HRO-50 and 60. Even though the National receivers have
rather narrow IF's the lack of distortion makes a difference
as noted above. This is not an exhaustive list, there were a
number of other receivers with high quality audio stages.
Many had a jack for a crystal phonograph pickup in order to
get double duty from the audio stage.
The Super Pro is a favorite of mine as you can probably
tell:-)




--
Richard Knoppow
Los Angeles
WB6KBL

What's an easy way these days with limited audio xfrmrs around to get
the 600 ohm spkr output to 4 or 8 ohms?

--
Thanks & 73
Hank WD5JFR
"Richard Knoppow" wrote in message
...

"PJR" wrote in message
news:XpmdncIb_cmzlJzUnZ2dnUVZ_rmdnZ2d@metrocastcab levision.com...
On Wed, 22 Oct 2008 11:33:14 -0500, Henry Kolesnik wrote:

I ended up with this & it's separate power supply in a package deal,
couldn't buy what I wanted without taking it. It looks better than
average but doesn't have the original S-meter. Both are rack mount
units in cases with a heavy interconnecting cable, and they are
heavy!
It covers 1.25 to 40 Mc in 5 bands. Both units have aluminum tags
with
serial numbers and the Rx is stamped Type O with a 40,000 serial.
I've
heard that they have terrific audio but with only a portion of BCB
it's
a bummer.
I'd like to know a bit more about it and if they have any value as
collectors items or are they true boat anchors? Is it a BC-794 A or
B
or a SP-210-SX or what? Why did they make the power supply so
heavy?
Thanks

Yours should be a SP-210-SX or BC-794-B (1.25 - 40 MHz)

More info at:

http://www.roveroresearch.org/sp200/bc779.html

An interesting site. There were more military variations on the
Super-Pro than shown, for instance, there was a modification that
allowed the use of crystal control for fixed frequency operation. The
crystal unit was mounted behind the main tuning dial with two knobs
projecting above the dial, one for crystal selection and the other for
fine tuning just as in the SP-600. These were evidently used in
diversity operation with two or three receivers being linked together.
While most of the drift will be over in half an hour it really
takes many hours for the receiver to stablize, perhaps 12 hours. They
were meant for continuous operation and will not drift much when so
operated.
It has been a puzzle to me that Hammarlund did not use voltage
regulators for the later Super-Pro's not even the SP-400, even though
they did use them in the comtemporaneous HQ-100 and had the knowledge.
The HQ-and its later versions, also had temperature compensation.
Perhaps the temperature compensation would have required too much
redesign of the very complex tuning unit but voltage regulation would
have required little and is easily applied to existing receivers.
Some of the war time receivers, notably the Howard-built ones have
some other variations, probably due to shortage of parts. For instance
toggle switches are used for the BFO switch instead of a rotary
switch. Makes no difference to operation but doesn't look as nice.
One somewhat obscure effect of the high quality audio circuit is
that static and interference are less bothersom because the audio
circuit is not exagerating them with distortion. Most tube
communication receivers have very simple, single-ended, pentode output
stages with no feedback. The are big time distortion producers. The
difference is easily heard in a direct comparison. For instance, for a
receiver like the SP-600 which has a detector output listening to this
output on a good quality external amplifier in comparison to the
receiver's own amplifier is night and day. Its interesting that the
original ads for the SP-600, based on a developmental model, indicate
it had push-pull audio. I rather think that the desire to put the
entire receiver, including the power supply, on a single chassis
required some serious compromises including dropping the push-pull
circuit. The two chassis arrangement of the older Super-Pro's allows
room for the quite large audio stage, comprising three tubes and two
rather large transformers.
Some other receivers of the time also had push-pull amplifiers,
notably the SX-28 and SX-32, SX-27, SX-36 and the National NC-100,
NC-200 and later versions, and the HRO-50 and 60. Even though the
National receivers have rather narrow IF's the lack of distortion
makes a difference as noted above. This is not an exhaustive list,
there were a number of other receivers with high quality audio stages.
Many had a jack for a crystal phonograph pickup in order to get double
duty from the audio stage.
The Super Pro is a favorite of mine as you can probably tell:-)




--
Richard Knoppow
Los Angeles
WB6KBL

"Henry Kolesnik" wrote in message
...
What's an easy way these days with limited audio xfrmrs around to get the
600 ohm spkr output to 4 or 8 ohms?

120 Volt to 12 Volt power transformer. Good at least down to 50 Hz or
better.

W4ZCB

Henry Kolesnik wrote:
What's an easy way these days with limited audio xfrmrs around to get
the 600 ohm spkr output to 4 or 8 ohms?

70V PA distribution transformers.

A 70V distribution transformer with an eight-watt input tap will give you
600 ohms input.

Old 70V equipment is usually available free for the asking from your local
installed sound company.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."