Richard
Having the dial up goes with the SP, hi hi. I did connect the 500 to
the fil xfrmr pri. I was a GCA tech in he air force, worked as a radio
and TV tech in high school and college and am a grad engr and have a bit
of experience. And I 've had a few SP 600s but this is my first Super
Pro 200. 1.25 to 40 Mcs, xtal filter, S-meter and 60 cps pwr supply and
stamped Type O after all the patents. It's kind of a neat boatanchor
that I've never played with before and for some unknown reason I keep on
playing with it. I wish it had the full BCB but it's nice on CW & SWL.
After being on all day I don't notice that much drift. It is just about
right on on all the WWVs, but all you know about other frequencies is
the first 2 digits. I don't need the manual as I have a copy of a copy
of copy and the TM 11-866 but neither is really clear on the model
number.
I was offered $75 at the last hamfest and maybe I'll be lucky and get
closer to the $150.00 I have in it or trade for some other beast.
73
Hank
"Richard Knoppow" wrote in message
m...
"Henry Kolesnik" wrote in message
...
Richard
The volume decreased with the filament transformer so I need to open
it up and see if someone made some mods. I downloaded the military
manual.
It seems to me that someone at Ham went nuts changing model numbers
for very insignificant reasons.
Note that the military type numbering was not done by Hammarlund.
The Super-Pro went through three versions, the SP-100, the SP-200, the
SP-400. The SP-100 was available in three versions with different
frequency ranges, the SP-400 in two ranges. The SP-100 was also
available with or without the crystal filter (I've never seen one
without) but evidently the filter could be retrofitted. All three were
also available in table or rack mount versions. There were at least
two power supplies, a standard and a 50 hz supply. The 50hz supply
will work on 60hz but not the other way. The last military versions
came with solid state power supplies.
There are some circuit differences between the different frequency
ranges. The standard version and the aircraft frequency version (100
to 400khz) have series fed RF stages with some loading on the low
frequency range and broadcast range of the standard version to broaden
out the RF bandwidth. The high frequency version (1250khz to 40Mhz)
has shunt-fed RF to keep the DC out of the RF coils. The coils have
ferrite cores so removing the DC sharpens them up a bit, which is
needed for a single conversion receiver operating a the higher part of
the frequency range. A similar arrangement is used in the SP-400 and
SP-400S (the last has the same 1250 to 40Mhz range).
The three frequency range receivers had different military type
numbers.
The SP-210 is the same as the SP-200 but came with a 10"
loudpeaker, there was also a SP-220, again the same chaissis with a
12" speaker. The standard version had an X on the end of the number
(SP-210X) indicating it had the crystal filter, the high-frequency
coverage version had an S on the model number as well as the X for
crystal, vis: SP-210SX.
The first versions, the SP-100 had glass multi-pin tubes with
external sheilds, the SP-200 was redesigned to use metal octal tubes
with do not need external shields. Otherwise the circuits are pretty
much the same.
The main virtue of the Super-Pro was the band switching
arrangement. This is a very complex system of knife edge switches
operated by cams, presumably to reduce lead length. National achieved
something similar with the plug-in coils on the HRO and the sliding RF
box on the NC-100, 101, and later NC-200 and 240 types. This may
actually be a better arrangement. Hammarlund caught up by using a
rotary turret on the SP-600 and Pro-310. But, except for Hallicrafters
version of the Super-Pro, which also has a turret, I don't know of
many receivers that used this good, but complex arrangement. One
virtue of the Super-Pro is its excellent interstage shielding and lack
of spurious responses, probably at least in part due to the RF stage
arrangement. It is also a relatively low radiation reciever.
Note that both the sliding coil method of adjusting the mutual
inductance of the IF stages (and hence bandwidth) and the type of
crystal filter circuit were Hammarlund exclusives. The IF bandwidth
arrangement allows symmetrical expansion of the response curve where
some other methods cause the bandwidth to expand only on one side. The
crystal filter is arranged to vary the Q of the loading coil and,
again, does not change the center frequency or gain as the bandwidth
is changed, plus it uses a butterfly capacitor to adjust the phasing
again so the center frequency does not vary with the notch position.
This is a much more satisfactory system than the original Lamb filter
used on National and Hallicrafters receivers until pretty late in the
game.
I have the civilian version of the instruction book and will post
it to you via private e-mail if you can't find it. I am still on a
dial-up and its pretty big but its yours if you desire. BTW, it has a
long list of the patents used (mostly RCA and Hazeltine Labs) some of
which are interesting to chase down.
--
--
Richard Knoppow
Los Angeles
WB6KBL