That's good...........it sounds like you are really in a strong signal area.
Up here at our new location, things are pretty good. I think that the worst
area in Illinois in in the Barrington area. WBBM, WMAQ, and WGN are so
strong that external mixing spur occur in rusty rain gutters, etc. I realize
that these are MW frequencies we are talking about vs. the FM band image
responses that you are dealing with. As you get higher in frequencies, those
gremlins can become harder to tame.
I've still yet to do your audio mod to my FRG100................too many
receivers. I might be picking up a
McKay-Dymek DR-33. It depends when my friend gets bored with it.
Pete
wrote in message
oups.com...
My FM receivers seem to be OK although one of the stations has an image
due to the signal strength. Both the Palstar R30 and HF-150 that I had
in the past had the same FM pickup problem but it was no where near as
bad as the FRG-100 and it was only on a couple of frequencies if I
remember correctly. The interference could only be detected when the
antenna was disconnected and one manually scanned the bands. By using
the additional connector on the I put on the FRG's back panel along
with some toroidal filters on the 12V power cable I've reduced it to a
tolerable level that only seems to be present if the antenna is
disconnected. I also added a few additional toroids at equal places on
the power cable and that helped even more because they apparently broke
the cable into smaller effective electrical lengths instead of the full
physical length, which is, by the way a half-wavelength in the lower
part of the FM band.
Frank
Pete KE9OA wrote:
A McIntosh MR78 can handle that kind of environment. One of the tests
that
McIntosh used to do was to inject a 12V interfering signal at a 10MHz
offset
to make sure that it didn't cause an increase in distortion at the
frequency
of the desired signal. It works very well in the Chicago area. A
Luxman
T-110 was also good, as was a Nakamichi Model 430 tuner. There are
several
good FM tuners on the market, including the Onkyo units that do the
trick.
The early Magnum Dynalab FM tuners that had the discrete front ends
were
also pretty good, but some of the models are using one of the Philips
auto
radio chipsets, including the RF/Mixer section.
Whereas the FRG100 had those images breaking through on some of the
MW
frequencies in my area, the AOR7030 didn't exhibit that
characteristic. The
Lowe HF-150 doesn't have this problem either; nor does the Palstar
R30. The
latter three units do have a 45MHz 1st I.F.
Nice work, Frank.
Pete
"Stephan Grossklass" wrote in message
...
schrieb:
Believe me this problem drove me crazy for a while. My QTH is
essentially "bathed" in the FM rf from 3 100 kW FM towers that are
within a 6 mile radius and line of sight with the house. This
problem
seems to only occur in receivers with a 45MHz 1st IF.
Which would make images from +90 MHz possible, putting you straight
into
FMBCB. Signals would only need to find a way around the 30 MHz
lowpass
filtering, and there you have it. Your signal levels seem to
uncover the
limits of the PCB layout and grounding, pretty hardcore if you ask
me.
It would be interesting to know how a '7030 behaves in that kind of
environment. BTW, what kind of FM tuner can handle that kind of
"bath"?
It would take at least something along the lines of an Onkyo
T-4700, I
assume.
Stephan
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