"Ralph Mowery" wrote in
m:


"Lostgallifreyan" wrote in message
. ..
Does anyone know what the Sangean ATS-909's external antenna input
impedance
is?

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.

Who cares what the impedance is for that radio. Unless you plan on
putting up an antenna for one very narrow band of frequencies, the
impedance of the system will be all over the place. YOu can probably
run coax to the antenna and never have any problems.


Ok, so that's two people saying that could work, and sure, I won't be relying
on a single narrow range, I want to see what's out there and detectable. I
might want to limit peaks and troughs in sensitivity by using a 9:1
transformer though, as I read several times that it is a useful way to do
that for general SW listening via a long wire. That alone means I probably DO
need to care about impedance matching.

"Lostgallifreyan" wrote in message
. ..
"Ralph Mowery" wrote in
m:


"Lostgallifreyan" wrote in message
. ..
Does anyone know what the Sangean ATS-909's external antenna input
impedance
is?

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.

Who cares what the impedance is for that radio. Unless you plan on
putting up an antenna for one very narrow band of frequencies, the
impedance of the system will be all over the place. YOu can probably
run coax to the antenna and never have any problems.


Ok, so that's two people saying that could work, and sure, I won't be
relying
on a single narrow range, I want to see what's out there and detectable. I
might want to limit peaks and troughs in sensitivity by using a 9:1
transformer though, as I read several times that it is a useful way to do
that for general SW listening via a long wire. That alone means I probably
DO
need to care about impedance matching.

You need an impedance matching device otherwise incorrectly called
"antenna tuning unit". It doesn't tune the antenna, it only matches the
impedance
for a given frequency. The main loss will be with the aerial NOT being
resonant at your chosen frequency.
The only way you are going to find out is try what people have suggested,
then compare the results for yourself.

"IanT" wrote in
:

Ok, so that's two people saying that could work, and sure, I won't be
relying
on a single narrow range, I want to see what's out there and
detectable. I might want to limit peaks and troughs in sensitivity by
using a 9:1 transformer though, as I read several times that it is a
useful way to do that for general SW listening via a long wire. That
alone means I probably DO
need to care about impedance matching.

You need an impedance matching device otherwise incorrectly called
"antenna tuning unit". It doesn't tune the antenna, it only matches the
impedance
for a given frequency. The main loss will be with the aerial NOT being
resonant at your chosen frequency.
The only way you are going to find out is try what people have
suggested, then compare the results for yourself.


Thanks, that could be useful. I've heard of them, wasn't sure if I'd need
something beyond a means to reduce peaks and troughs in resonance or
sensitivity across bands while trying to match impedance though. I read some
old posts by John Doty (archived on web sites) that suggested that a single
device could be set and placed at the end of the antenna wire and grounded
there too, and then weatherproofed and ignored. It's an attractive idea.