Thomas, I wished I knew an answer.  When I was living up in Arkansas, both 
my HF and VHF antennas were in close proximity to my instruments and 
connecting cables.  Either mode caused interference while transmitting.

Since then, I have moved back to Texas and have just recently got my 
antennas back up.  Now, I do not get interference on HF, but do when on VHF. 
The HF is a vertical mounted on a chain link fence about 75 ft away, but the 
dual-ban VHF/UHF antenna is loser mounted on the house.

From that experience, I can only assume that the closer the antenna, the 
more likelihood of RF interference!  Furthermore, I only have one vertical 
seismic instrument, located within the house, and shorter run of connecting 
cables.

Sorry that I do not have an answer, but possibly some clues.  Do you think 
that winding a coil in your seismic leads would act as a choke?

Regards,
Jerry  AB5R

--------------------------------------------------------------------------------

  ----- Original Message ----- 
  From: Thomas Dick
  To: psn-l@..............
  Sent: Saturday, February 20, 2010 11:00 AM
  Subject: Ham radio interference


  Anyone got some suggestions; experiencing interference while
  transmitting ---
                                 my ham radio setup; FT101, FT757 and Icon 
207
                                 low band filtering, torroids on in power
  and grounds -- ground uses 6 ft copper coated rods
  ...                            only about 20 ft from a lake
  antennas; vertical for 2 meters at 60 feet, ground plane for ten meters
  at 80 feet, 160 meter, 80-40 inverted V

  my seismic epuipment; two 20 sec Lehmans, AS1 with magnetic induction,
  Larry Cochrane Amp, AD converter(in metal cases and grounded outside
  again with a separate 6 rod), 4.5 HZ geophones .. with isolation and
  battery backup.


  When I transmit on any band. drifting of the base line display occurs
  and spikes appear. I used to run 400 watts on 29.6 mHz (a repeater) but
  abandoned that after 25 yrs when I couldn't cure this problem. I
  recently put up the 80-40 meter antenna and have a 1:1.2 SWR.... still
  the interference is there! Any suggestions?
  __________________________________________________________

  Public Seismic Network Mailing List (PSN-L)

  To leave this list email PSN-L-REQUEST@.............. with
  the body of the message (first line only): unsubscribe
  See http://www.seismicnet.com/maillist.html for more information.







Thomas, I wished I knew an answer.  When I was living up in =
Arkansas,=20
both my HF and VHF antennas were in close proximity to my instruments =
and=20
connecting cables.  Either mode caused interference while=20
transmitting.
 
Since then, I have moved back to Texas and have just recently got =
my=20
antennas back up.  Now, I do not get interference on HF, but do =
when on=20
VHF.  The HF is a vertical mounted on a chain link fence about 75 =
ft away,=20
but the dual-ban VHF/UHF antenna is loser mounted on the house.
 
From that experience, I can only assume that the closer the =
antenna, the=20
more likelihood of RF interference!  Furthermore, I only have one =
vertical=20
seismic instrument, located within the house, and shorter run of =
connecting=20
cables.
 
Sorry that I do not have an answer, but possibly some clues.  =
Do you=20
think that winding a coil in your seismic leads would act as a =
choke?
 
Regards,
Jerry  AB5R




  
----- Original Message ----- 
  From:=20
  Thomas Dick 
  
To: psn-l@.............. 
  
Sent: Saturday, February 20, =
2010 11:00=20
  AM
  
Subject: Ham radio =
interference
  

Anyone got some suggestions; experiencing interference =
while=20
  
transmitting=20
  =
---
           =
            &=
nbsp;      =20
  my ham radio setup; FT101, FT757 and Icon=20
  =
207
           =
            &=
nbsp;      =20
  low band filtering, torroids on in power 
and grounds -- ground =
uses 6 ft=20
  copper coated rods=20
  =

...           =
            &=
nbsp;   =20
  only about 20 ft from a lake
antennas; vertical for 2 meters at 60 =
feet,=20
  ground plane for ten meters 
at 80 feet, 160 meter, 80-40 inverted=20
  V

my seismic epuipment; two 20 sec Lehmans, AS1 with magnetic=20
  induction, 
Larry Cochrane Amp, AD converter(in metal cases and =
grounded=20
  outside 
again with a separate 6 rod), 4.5 HZ geophones .. with =
isolation=20
  and 
battery backup.


When I transmit on any band. =
drifting of=20
  the base line display occurs 
and spikes appear. I used to run 400 =
watts on=20
  29.6 mHz (a repeater) but 
abandoned that after 25 yrs when I =
couldn't cure=20
  this problem. I 
recently put up the 80-40 meter antenna and have a =
1:1.2=20
  SWR.... still 
the interference is there! Any=20
  =
suggestions?
_________________________________________________________=
_

Public=20
  Seismic Network Mailing List (PSN-L)

To leave this list email =
PSN-L-REQUEST@...............
=20
  with 
the body of the message (first line only): unsubscribe
See =
http://www.seismicnet.co=
m/maillist.html=20
  for more information.