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.

On Dec 19, 3:14*pm, Lostgallifreyan wrote:
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.

just hook it up with the coax even without the transformer and it
should be fine.

Dave wrote in news:f119aab9-3597-4cba-ac75-
:

On Dec 19, 3:14*pm, Lostgallifreyan wrote:

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.

just hook it up with the coax even without the transformer and it
should be fine.


Really? Wouldn't that be 'matching' a fairly high impedance in the wire to
the low 50 ohm coax, then risking further loss in unknown input impedance
mismatch? I like the idea though, if I thought it would be that easy I might
have tried it. If it's really ok I'll do it. I haven't got scope for a
really long wire so I do need to try to minimise losses, I imagine..

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

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.

There's a 1K0 pot across the input which is used as a cheap and cheerful
RF gain control. So i'd assume about 1K. You wouldn't have a problem
with the wire attached direct, but you'll get lots of front end
intermod, as it's wide open - just a low pass filter (presumably 30MHz
cut off)before the RF amp. A bit of preselection is pretty necessary for
an external wire of any size.

Gaius wrote in
:

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

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.

There's a 1K0 pot across the input which is used as a cheap and cheerful
RF gain control. So i'd assume about 1K. You wouldn't have a problem
with the wire attached direct, but you'll get lots of front end
intermod, as it's wide open - just a low pass filter (presumably 30MHz
cut off)before the RF amp. A bit of preselection is pretty necessary for
an external wire of any size.



Front end intermod? Do you mean pickup from local active gain stages or other
RF subcircuits in the receiver being picked back up by the wire antenna and
makign sum/difference signals or similar effects?

Also, I see that pot now, (and noticed that it also affects the telescopic
inbuilt antenna's pickup on SW (not FM as far as I know)), but I also see a
lot of other parts associated with that part of the circuit. I don't know
enough to be sure but it seems they might complicate the picture. If not, I
don't know why the impedance seems to be a mystery. If it were well
established I know my searches would found it so in triplicate by now...

Lostgallifreyan wrote:
Gaius wrote in
:

Lostgallifreyan wrote:

Also, I see that pot now, (and noticed that it also affects the telescopic
inbuilt antenna's pickup on SW (not FM as far as I know)), but I also see a
lot of other parts associated with that part of the circuit. I don't know
enough to be sure but it seems they might complicate the picture. If not, I
don't know why the impedance seems to be a mystery. If it were well
established I know my searches would found it so in triplicate by now...

I've just found a schematic JPG - 475Kb. It claims to be a "RK777", but
I think that's one of the 909's aliases. I can send it - mail me at john
at aultmore dot net.

Gaius wrote in
:

Lostgallifreyan wrote:
Gaius wrote in
:

Lostgallifreyan wrote:

Also, I see that pot now, (and noticed that it also affects the
telescopic inbuilt antenna's pickup on SW (not FM as far as I know)),
but I also see a lot of other parts associated with that part of the
circuit. I don't know enough to be sure but it seems they might
complicate the picture. If not, I don't know why the impedance seems to
be a mystery. If it were well established I know my searches would
found it so in triplicate by now...

I've just found a schematic JPG - 475Kb. It claims to be a "RK777", but
I think that's one of the 909's aliases. I can send it - mail me at john
at aultmore dot net.


Thanks, but I'm ok, I got a schematic.. It just appears that those links
became forbidden access in the week or so since I found them. Might even be a
local error, thogh as I no longer do HTML or User-Agent filtering or similar
things I can't see what the cause might be.

"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.

"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.