This is a multi-part message in MIME format.
------=_NextPart_000_000C_01BE78F7.0DE02080
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
This is a restatement of a problem that a ham was kind enough to post =
for me ...
I have a lot of trouble with receiver overload on my FT-1000, apparently =
when I'm using physically large antennas. The antennas are a 195 foot =
long Marconi (52 foot vertical, 143 foot horizontal) and a 180 foot long =
dipole (c.f. zepp?) feed with twin lead.
These antennas present "reasonable enough" impedences so that the FT1K's =
ATU can load OK and transmit on several bands, but serious receiver =
noise from overload is a big problem. The AM station doesn't seem THAT =
powerful or THAT close to me: It's about 1 KW day and 500 W night and =
is about a mile or so away. I'm sure it's overload because switching in =
a few steps of attenuation will make it drop out completely while =
desired signals are merely attenuated as expected.
Questions: I read some years ago that some transceivers don't use their =
ATUs on receive. I wonder if this is the case with the FT1K. Or maybe =
with early S/Ns?
Also since these antennas aren't presenting a good 50 ohm impedence at =
the antenna terminals I assume using an outboard high pass filter might =
be a problem. (Filters need a good match, I'm told.) Maybe it would be =
possible to add one internally, ahead of the receiver section. It would =
degrade receiver performance below 160 meters but might be worth it. =
Anyone tried anything like this? Any other insights or ideas for me?
73,=20
Nick, WA5BDU
nkennedy@cswnet.com
------=_NextPart_000_000C_01BE78F7.0DE02080
Content-Type: text/html;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
<!DOCTYPE HTML PUBLIC "-//W3C//DTD W3 HTML//EN">
<HTML>
<HEAD>
<META content=3Dtext/html;charset=3Diso-8859-1 =
http-equiv=3DContent-Type>
<META content=3D'"MSHTML 4.72.3110.7"' name=3DGENERATOR>
</HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" size=3D2>This is a =
restatement of=20
a problem that a ham was kind enough to post for me ...</FONT></DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" =
size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" size=3D2>I have a =
lot of trouble=20
with receiver overload on my FT-1000, apparently when I'm using =
physically large=20
antennas. The antennas are a 195 foot long Marconi (52 foot =
vertical, 143=20
foot horizontal) and a 180 foot long dipole (c.f. zepp?) feed with twin=20
lead.</FONT></DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" =
size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" size=3D2>These =
antennas present=20
"reasonable enough" impedences so that the FT1K's ATU can load =
OK and=20
transmit on several bands, but serious receiver noise from overload is a =
big=20
problem. The AM station doesn't seem THAT powerful or THAT close =
to=20
me: It's about 1 KW day and 500 W night and is about a mile or so=20
away. I'm sure it's overload because switching in a few steps of=20
attenuation will make it drop out completely while desired signals are =
merely=20
attenuated as expected.</FONT></DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" =
size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" =
size=3D2>Questions: I read=20
some years ago that some transceivers don't use their ATUs on=20
receive. I wonder if this is the case with the FT1K. Or =
maybe with=20
early S/Ns?</FONT></DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" =
size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" size=3D2>Also since =
these antennas=20
aren't presenting a good 50 ohm impedence at the antenna terminals I =
assume=20
using an outboard high pass filter might be a problem. (Filters =
need a=20
good match, I'm told.) Maybe it would be possible to add one =
internally,=20
ahead of the receiver section. It would degrade receiver =
performance below=20
160 meters but might be worth it. Anyone tried anything like =
this? =20
Any other insights or ideas for me?</FONT></DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" =
size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" size=3D2>73, =
</FONT></DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" =
size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" size=3D2>Nick, =
WA5BDU</FONT></DIV>
<DIV><FONT color=3D#000000 face=3D"Times New Roman" size=3D2><A=20
href=3D"mailto:nkennedy@cswnet.com";>nkennedy@cswnet.com</A></FONT></DIV><=
/BODY></HTML>
------=_NextPart_000_000C_01BE78F7.0DE02080--
--
FAQ on WWW: http://www.qsl.net/k7on/yaesu.html
Submissions: yaesu@contesting.com
Administrative requests: yaesu-REQUEST@contesting.com
Problems: owner-yaesu@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|