Hi,
I am pretty liberal in the use of chokes here... I have a single snap
on on each end of every jumper, (mix31), A large one made from 5
FT240/31 rings, at the input to the house, and at the base of every
antenna.
I also have many many smaller devices using the RG-8 ferrite, and use
the ferrite to take up all slack for all externally powered devices.
This always gets at least 5 to 10 turns on the RG-8 ferrite for the
power items... I also have 4 of 5 snap on's on the main power feed to
the shack, and a filter as well.
I have almost no RFI as a result of this. I am sure I could remove a
few, but they are cheap when you purchase in bulk. See Jim's papers on
use for ferrite for more info...
http://audiosystemsgroup.com/RFI-Ham.pdf
I have a small write up on a total shack rebuild at:
http://nk7z.net/rebuilding-the-shack/
--
Thanks and 73's,
For equipment, and software setups and reviews see:
www.nk7z.net
for MixW support see;
http://groups.yahoo.com/neo/groups/mixw/info
for Dopplergram information see:
http://groups.yahoo.com/neo/groups/dopplergram/info
for MM-SSTV see:
http://groups.yahoo.com/neo/groups/MM-SSTV/info
On Thu, 2015-02-26 at 18:46 -0500, Wm.Glenn Pearson wrote:
>
> Where does one need to place chokes with multiple RF handling boxes in the
> chain? My layout is”
>
>
>
> 160 M Twin Lead (300 ohm ladder line) and 80 M Twin Lead (etc.).
>
> 40 M – 12 M 43 ft Vertical
>
> 20 – 10 M tribander.
>
> (Total of 4 antennas)
>
>
>
> Each antenna connects to a ¼ inch thick copper bulk head plate outside the
> window of my shack. The bulk head is bonded to my house ground (and
> utilities). My system ground inside is bonded to the above mentioned
> bulkhead.
>
>
>
> Each antenna feeds a multiple position Alpha Delta Switch. Then the chain
> flows as: antenna selected > auto tuner > low pass filter > transceiver. The
> cables between the bulk head and the switch are approximately 10 feet in
> length. Inter connecting cables between the switch, tuner, amp and low pass
> filter are no more than 3 feet long (if that much). The cable between the
> transceiver and the amp is RG-214 and about 12 feet long. I am not able to
> get the transceiver any closer to the other equipment due to the physical
> layout of the room and my operating desk.
>
>
>
> Currently I have each jumper between boxes broken with inline RF chokes. I
> now realize they are the wrong material and not sufficient for suppression.
> I am having significant interference on 10 M. The same is present on 15 and
> 20 M to a much lesser extent. The same interference is not present (the best
> I can tell) on 160 and 80 M (Twin Lead Marconi’s) although there are other
> noises sources who origins have not been determined as yet.
>
>
>
> Initially I was going to construct two of Jim’s chokes (type 31 Fair-rite
> toroids) and place them (in series) at the transceiver. The second choke
> will have fewer turns of RG-213 to get the 10 M coverage I need. Where else
> do I need to place a choke (s). I am trying to put together an order for
> Fair-rite suppression materials, toroids, clamp-ons, and etc. I have a very
> good idea of what I need to suppress noise relating to the interconnects
> between computers, monitors, cable modem, router, network switch and etc.
>
>
>
> The source(s) of the interference is another topic in itself but I am on top
> of that.
>
>
>
> Thanks
>
>
>
> Glenn Pearson, WU2G
>
>
>
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