It's called a counterpoise.
When all else fails, sometimes this works wonders.
Cut a length of wire (any kind, it doesn't matter) to the half wave
length for the band you wish to operate, and stretch it out on the
floor, zigzag if necessary.
Attach one end to the ground screw on the rig.
This was another of the tricks my Elmer suggested for my 2nd floor
shack, right under the antenna mounted on the roof.
On 10/31/2010 9:48 AM, Tim Ellison wrote:
Laptops are problematic in this regard. You can try to use the screw posts on
one of the back connectors, like the video connector. Or use a lot of split or
solid core ferrite beads on the Firewire cable to start with.
Jim's advice is very good too. Removing the common mode RF currents from the
antenna coax shield using a choke balun before they get back to the radio
hardware is the best way eliminate RFI problems.
-Tim
-----Original Message-----
From: Russell Magnuson [mailto:r...@resultsdirect.com]
Sent: Sunday, October 31, 2010 9:16 AM
To: Tim Ellison; flexradio@flex-radio.biz
Subject: Re: Flex-3000 freezing up on transmit
Tim, I am using a notebook computer so a more formal ground technique eludes me
(short of drilling holes into it in order to connect to its internal ground
plan...). I'm not sure it even has a grounded metal shell type connector on it
that I could connect to. So any advice you have would be appreciated. I am
assuming that currently my best path to the Flex-3000 ground is through the
shield in the firewire cable.
- Russ, KFiK
On 10/30/10 3:44 PM, "Tim Ellison"<telli...@itsco.com> wrote:
Do you have the PC grounded to the radio?
Also you may need more ferrite beads on the Firewire cable
http://kc.flexradio.com/KnowledgebaseArticle50370.aspx
-Tim
-----Original Message-----
From: flexradio-boun...@flex-radio.biz
[mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Russell
Magnuson
Sent: Saturday, October 30, 2010 3:00 PM
To: flexradio@flex-radio.biz
Subject: [Flexradio] Flex-3000 freezing up on transmit
Hello all,
I have been fighting a problem with my Flex-3000 setup (or one that it
is a victim of) which I believe... is related to RF getting back into
it and freezing it up (Problem: display wave form freezes on transmit
after modulation, Flex-3000 requires a power cycle/PSDR needs to be
restarted on my notebook PC).
At first I thought it was a problem with my firewire card and all
that, but eventually got to try transmitting into a dummy load and
under this scenario the rig does not freeze up when transmitting (all
the way up to full power out/100w).
Other details:
* 50¹ of LMR-400 feeding a Radiowavz OCF DX 80 ( replaced RG-8X with
the
LMR-400 as part of my debug process here)
* Insertion/use of an external tuner does not seem to change the
symptoms or prevent freeze up
* Increasing output power (and Mic gain to drive it) beyond a few
watts into the antenna causes it to crash
* Problem seems to be worst on 40m, but I have had it crash on 20m as well.
Higher bands seen less prone to crashing
Grounding:
I have been trying different grounding things but to no avail. I DO
NOT currently have a 8¹ rod handily pounded into the ground nearby. I
have tried the incoming copper water pipe in addition to normal A/C
house ground (I also tried a 50¹ run of RG-8x to that incoming water
pipe, with the C/S shorted on the pipe end and a .01uf ceramic cap
between the center and the shield on the other end, where I then connected the
center to the GND on the Flex-3000).
Other rigs:
Prior to purchasing the Flex-3000 I have been running my FT-897D into
this same antenna setup with no known (or detected) issues related to
ground or RFI, etc.
Thoughts? Ideas? Theories? What am I missing here? Is there anything
in the
Flex-3000 that maybe is futz in some way that would make it
hypersensitive to some RF(???) in the shack? Or am I missing some other angle
here?
Thanks in advance,
Russ, KF1K
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--
---------------------------
A man who lives in a glass house should change in the basement.
---------------------------
Bill H. in Chicagoland
webcams at http://w9ol-towercam.webhop.org
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