[Premium-Rx] Sherwood SE-3

[Guy Atkins]

Another external synchro-AM detection box to keep an eye out for is the Kiwa
"MAP" (Multiband AM Pickup). It is a competitor to the SE-3 from the early
ninties, but in my opinion it offers comparable performance with more
features and sturdier, more attractive construction. It was one of Kiwa
Electronics' first products, and Craig Siegenthaler over-designed it
physically (rounded-corner custom cabinet w/40+ case screws, high grade
powdercoat paint, etc.) so that it ended up too expensive to sell
profitably. The MAP's owners manual is a thing of beauty, with full
schematics, specs & information which rivals the best receiver manuals.

Features beyond synchro-AM detection in the MAP include dual bandwidths
(cascaded ceramics similar to Kiwa's current Filter Modules) that supplement
the receiver's own filters depending on the IF "pick-off" point"; a true
tone tilt control a la audiophile stereo gear; a tunable audio filter; 455
IF signal output & recording outputs; and a carefully-chosen internal
speaker matched to the enclosure (Craig tested lots of manufacturer's
samples before settling on a speaker). All front panel switching on the MAP
is done with soft-touch FET-controlled pushbuttons. The MAP uses either a
direct IF pickup either pre- or post- receiver filtering or to the product
detector in some receivers, or an indirect pickup using an IF "sniffer" coil
(recommended for any receiver with a DC voltage higher than 50v at the
pickup point).

Craig had his production MAP tested by the Hatfield & Dawson engineering
group of Seattle, to verify the performance specs. Each MAP included a
"Certificate of Performance with specific figures for each unit. Among other
data, mine shows the following:

Wideband filter response: +/- 2.0dB 50 Hz-3.0 kHz "OK"
-6dB point: 3.23 kHz
-60dB point: 4.27 kHz
Shape Factor -60/-6dB: 1.32
Ultimate Rejection at 6 kHz: -101 dB

The figures for the narrow bandwidth include a measured -6dB point of 1.47
kHz, and measured ultimate rejection of -108dB.

These bandwidths make for some useful additional selectiity when cascaded
with the receiver's own filters.

I recall one particular session with the MAP in 1991 or 1992. During a March
WA coastal DXpedition at Grayland, we monitored for minimum discernable
signal on 1566 kHz (HLAZ, Chenju, S. Korea). A JRC NRD-525 lost audio and
then eventually the het at 2 hours past local sunrise. However, switching in
the MAP restored weak audio when the signal was only a het with the NRD
alone. The het was finally lost on the 525/MAP combo an amazing 3 hours past
local sunrise.

The Kiwa MAP was only manufactured until 1992, but occasionally one shows up
on the used market. They were made extremely durable, so unless one has been
abused it should still perform very well. My current Kiwa MAP was recently
acquired as NOS, new in the box from Craig when he moved his business to
Minnesota. Evidently it is the last MAP made... serial #109.

Craig's plans for a "MAP II" never materialized, unfortunately. He had
planned rework the mechanical aspects to make it more profitable to produce,
and add a second, PLL-type synchronous detector for the user to choose from.

BTW, the MAP was reviewed by me in-depth for an early edition of the Fine
Tuning's "Proceedings" series of books; I think it was the 1991 or 1992
edition.


Guy Atkins
dx at guyatkins.com
Puyallup, WA USA



-----Original Message-----
From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org]On Behalf Of Dan Neves
Sent: Friday, April 04, 2003 10:35 AM
To: premium-rx at ml.skirrow.org
Subject: [Premium-Rx] Sherwood SE-3



	Hello everyone:

	Recently there has been a Sherwood SE-3 here in the shack and
perhaps a comments are in order. A couple of Racals are in use here with
the 455khz IF out required for the SE-3. I assume most of us know of
this item, it is an external phase locked detector that allows SSB and
PBT for AM only receivers and more...
<SNIP>