On Sun, 20 Dec 2009 04:01:16 -0600, Lostgallifreyan
wrote:

Bob wrote in
:

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


3.5mm, not 2.1mm

"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."


I know that, it was the first thing I found, but it doesn't answer any
questions about impedance, especially if the radio you buy is second hand and
doesn't have the antenna wire with it.

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.


Agreed, which is why I don't assume it's 50 ohms, and I start looking for
answers. I think you're likely right that it might not make enough difference
to worry about though. If using coax can get the SNR higher I'm in business
so long as the signal is strong enough for the input's gain to use.

You might shoot an email to tech at C.Crane Co. -- a lot of their
branded radios are actually customized Sangeans...they might be able
to tell you the most effective antenna and/or the impedance of the
thing.

bob
k5qwg

Bob wrote in
:

You might shoot an email to tech at C.Crane Co. -- a lot of their
branded radios are actually customized Sangeans...they might be able
to tell you the most effective antenna and/or the impedance of the
thing.

bob
k5qwg


Nice, I saw their page, didn't check that far though, and it is worth a try.

Bob wrote in
:

You might shoot an email to tech at C.Crane Co. -- a lot of their
branded radios are actually customized Sangeans...they might be able
to tell you the most effective antenna and/or the impedance of the
thing.

bob
k5qwg


I got a reply, but Sangean didn't tell them that either. But he says what
many here do, that it doesn't matter that much, and that 50 ohm line should
be ok.

One thing that keeps coming up is the need to make my own transformer for the
far end, whatever scheme I use, and in that context I often see mention of a
ferrite co Amidon FT-114-75 (AL about 3000, permeability u=5000, about
1.14 inch outside diameter as described on one page). Cheap but apparently
not easy to find in Britain. Does anyone know a current source of something
equivalent to it? It's beginning to look like I should get a small handful of
them. Another thing that might be better fetched locally is something like
the broadband preamp for LW to 30 MHz sold by Kiwa Electronics. If anyone
knows of one, please point me to it.. It's a Norton balanced input amp with
gain of around 10 dB. Even if I don't need it I'd like to know where to find
such things locally. I can likely build something based on the Dallas design
in a PDF I found but a good picture of the construction would help, as I
can't easily visualise the coil and former arrangements from the schematic.