I have 2 R2000s and a DX398. Radios not known for their wide
danamic range. I use a ~70' wire antenna, with a 9:1 tranformer,
(with another 1:1 for ground noise isolation) and I have very little
problem with overload. A ham who operates at(or beyond) legal
power lives about 2 miles form me and when he fires up, I do
have to leave the band he is operating on. But I used to own a
R390/URR and a R392/URR and both suffered the same problem.
I borrowed a R5000, and a PCR1000 and the R5000 was
slightly better. The PCR1000 was a POS joke. The DSP was nice,
but I guess I'm a "horse drawn man", and a radio must have knobs.
My Heath GR64 doesn't have any overload issuses, but given it
is a deaf as a post, I am not shocked.

I supect that with a decent antenna, a good matching overload
maybe on over blown issue.

Terry

TERRY,
..
The RadioShack DX-398 / Sangean ATS-909 is 'noted' for being the
exception to the rule; that most 'portable' AM/FM Shortwave Radios
have a tendancy to OverLoad with a very long (+100) Wire Antenna.
..
Conversely, some complain that the RadioShack DX-398 / Sangean
ATS-909 is some what deaf on it's Whip Antenna when compaired
to other 'portable' AM/FM Shortwave Radios.
..
jm2cw ~ RHF

I am happy to learn the DX398 is above par in that regards.
I thought that I had read somewher that it was fairly prone to
overload.
I have used my R2000 with about 800' of wire up in a nature
preserve and had no noticable problems. We camped out,
in a VW transporter, and I listened on and off for 2 days.
BTW your antenna site if a very well organised place and
full of interesting info.

Terry

wrote:

I have 2 R2000s and a DX398. Radios not known for their wide
danamic range. I use a ~70' wire antenna, with a 9:1 tranformer,
(with another 1:1 for ground noise isolation) and I have very little
problem with overload. A ham who operates at(or beyond) legal
power lives about 2 miles form me and when he fires up, I do
have to leave the band he is operating on. But I used to own a
R390/URR and a R392/URR and both suffered the same problem.
I borrowed a R5000, and a PCR1000 and the R5000 was
slightly better. The PCR1000 was a POS joke. The DSP was nice,
but I guess I'm a "horse drawn man", and a radio must have knobs.
My Heath GR64 doesn't have any overload issuses, but given it
is a deaf as a post, I am not shocked.

I supect that with a decent antenna, a good matching overload
maybe on over blown issue.

Terry


As I understand it, it is the front end transistor(s) that are being
overloaded when somebody talks about "antenna overload". This problem
occurs mostly with cheap portables. Since they are built cheaply, the
front ends are also cheap and do not have the selectivity of a better
quality receiver. Clipping a length of wire to the whip of one of these
portables will pick up images mostly of AM and FM stations that are in
the vicinity of the receiver. For example, I have a cheap Radio Shack
AM/FM radio that is easily overloaded. Just pointing the whip antenna in
the direction of the nearest FM station (about two miles away) is
sufficient to produce images of that station all over the dial. The
problem is not with the whip, it is the front end.

RD,
..
Replace "front end transistor(s)" with Front End RF Circuitry.
..
YES - You are right many low cost 'portable' AM/FM and Shortwave
Radios are poorly designed and have various images and signal
products that can be hear all over their tuning range. As much
as nearby AM/MW Radio Stations can be a problem. So too, as
you point out nearby FM Radio Stations can be a very real signal
'overload' problem for these cheap portable and table top Radios.
..
Fortunately for Us as Radio Enthusiast for every dozen or so of
these low cost poorly designed Radios. There are a few well
designed Radios that are 'quality built' like the: Sony ICF-2010,
Sangean ATS-909, Grundig Yacht Boy 400 PE, to name a few.
..
CHECK-OUT - DXing.Com's "Modern Shortwave Receiver Survey List"
DXING COM = http://www.dxing.com/rx/rxindex.htm
For some of the better 'portable' AM/FM Shortwave Radios
and some outstanding Table Top Shortwave Receivers.
..
jm2cw ~ RHF

In article .com,
wrote:
I have 2 R2000s and a DX398. Radios not known for their wide
danamic range. I use a ~70' wire antenna, with a 9:1 tranformer,
(with another 1:1 for ground noise isolation) and I have very little
problem with overload. A ham who operates at(or beyond) legal
power lives about 2 miles form me and when he fires up, I do
have to leave the band he is operating on. But I used to own a
R390/URR and a R392/URR and both suffered the same problem.
I borrowed a R5000, and a PCR1000 and the R5000 was
slightly better. The PCR1000 was a POS joke. The DSP was nice,
but I guess I'm a "horse drawn man", and a radio must have knobs.
My Heath GR64 doesn't have any overload issuses, but given it
is a deaf as a post, I am not shocked.

I supect that with a decent antenna, a good matching overload
maybe on over blown issue.

When you've got a quarter of a million watts of medium wave transmitters
blinking their tower lights on your horizon, it's a problem. And I'm
5-7 miles away.

Especially with a Kenwood R-1000 which uses diode switched bandpass
filters in the front end. Since I got a portable to tote around,
I found that If I want to use another receiver in the house, I have
to turn on the R-1000 to bias the diodes on or off, (or disconnect the
antenna), otherwise the spectrum is filled with intermod reradiated from
the antenna.

[Diety] help any radio buff who lives in Federal Way/Vashon Island or near
any other large metro area's medium wave transmitter patch. I heard a
story about a MARS operator/ham there who was having problems with
an on frequency harmonic on a MARS channel around 4 MHz. The FCC guy he
talked to said (words to the effect), Yup, it's right on your frequency,
a couple of miles away, 100 milliwatts, and within the legal limits. Sorry.

Mark Zenier Washington State resident

running dogg wrote:

As I understand it, it is the front end transistor(s) that are being
overloaded when somebody talks about "antenna overload". This problem
occurs mostly with cheap portables. Since they are built cheaply, the
front ends are also cheap and do not have the selectivity of a better
quality receiver. Clipping a length of wire to the whip of one of these
portables will pick up images mostly of AM and FM stations that are in
the vicinity of the receiver. For example, I have a cheap Radio Shack
AM/FM radio that is easily overloaded. Just pointing the whip antenna in
the direction of the nearest FM station (about two miles away) is
sufficient to produce images of that station all over the dial. The
problem is not with the whip, it is the front end.

Correct, which includes the first mixer too. Either the front end needs
better preselection using some kind of LC circuits and/or the active
componants (transistors) need to be operated at higher voltages to
provide more 'headroom' from overloading. A good receiver uses both
methods in conjunction with well designed RF amp's and mixers'.


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Mark Zenier wrote:

When you've got a quarter of a million watts of medium wave transmitters
blinking their tower lights on your horizon, it's a problem. And I'm
5-7 miles away.

Especially with a Kenwood R-1000 which uses diode switched bandpass
filters in the front end. Since I got a portable to tote around,
I found that If I want to use another receiver in the house, I have
to turn on the R-1000 to bias the diodes on or off, (or disconnect the
antenna), otherwise the spectrum is filled with intermod reradiated from
the antenna.

You could try replacing the standard switching diodes with a hot carrier
PIN type like the 1N5711.


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