On Sat, 19 Dec 2009 09:14:46 -0600, Lostgallifreyan
wrote:

Does anyone know what the Sangean ATS-909's external antenna input impedance
is?

The Sangean external antenna input is a 2.1mm jack which would
acommodate a high impedance long wire, as per the instructions:

"ANT-60 PORTABLE SW ANTENNA
Included with the ATS-909 is the Sangean ANT-60 Portable SW Antenna.
The antenna is plugged into
jack (26) labeled EXT AM ANT. When fully extended this antenna should
improve SW reception. For
maximum performance this antenna should be placed as high as possible
above the ground and in an
unobstructed area if possible."

Your idea of attaching the antenna via 50 ohm coax would probably be
below the impedance range of the jack, tho' I'm not sure you would
really hear much difference.

If the Sangean external antenna input were designed for 50 ohm coax,
it would probably have a coax jack, not the 2.1 mm jack.

bob
k5qwg



I searched for days for documentation on that radio and found plenty, mods,
schematics, service manuals, reviews, but no straight word on the impedance
of that input! (Not even in the service manual specs). The only reference I
found was a from a guy on a 7-page set of ham reviews, and all he said was
that it was a mystery!

Maybe the only way to know is to start from the schematic but I don't know
how, but here's the best schematic I could find:
http://eric.horsemensociety.info/TEC...chematic_A.gif
(Antenna input is near top right).
(Link appears to be dead, 403, forbidden. I'm sure it worked last week..)

What I really want to know is whether the ATS-909 will work ok with a
long(ish) wire outside feeding a 50 ohm coax via a 9:1 transformer, or if
that would cause more bother than connecting a wire directly to it and
putting up with local noise picked up from nearby buildings.