Charles,
Yes you are correct. In my previous post I failed to take the square
root so the turns are 3 instead of 11. Also, if you are building a
choke balun for your coax, type 43 material is preferable to type 77
material because it will not saturate as easily as type 77 material. I
have
Charles,
The equation is: L = (N2*Al) / 100 where L is in mh or L = (N2*Al) /
1000 where L is in uh. Using an Al = 1270 with one turn, then L = 1.27
uh. If N is doubled to two then L = 22*Al/1000 or 5.08 uh. You have
two errors in your text. You switched from mh to uh and you failed
Hi,
I am getting some RF feedback when I use a Linear amp that causes the
USB to Parallel connection to occasionally disconnect. The system
ground is about as good as I can reasonably get it except for the
Laptop itself. It doesn't happen with the SDR-1000 100 watt
amp. There doesn't appear
Charles,
Get an FT-114-77 ferrite toroid from Palomar Engineering and wrap as
many turns of the USB cable as you can on the core.
Tom W0IVJ
Charles Greene wrote:
Hi,
I am getting some RF feedback when I use a Linear amp that causes the
USB to Parallel connection to occasionally
You did not tell us much about your setup there, so this will be pretty
broad. Some likely sources of rfi are the coax cabling if you are
feeding your antennas with coax, and/or the interconnects between your
individual pieces of gear. You must get the rf off the outer shields. RF
If you are a open wire feeders are best sort of guy, good luck... The
reason open wire feeders are zero loss is that the feeders themselves
radiate.
The reason open wire feeders radiate is because the current in the two wires
are unbalanced. If you balance the currents, the loss remains
Correct me if I am wrong here but, open wire feeders by themselves are
balanced - its the load they feed into which determines if the system is
balanced or unbalanced.
Stan
AH6JR
On Wednesday 07 March 2007 5:54 am, Tom Thompson wrote:
If you are a open wire feeders are best sort of
.
Van: [EMAIL PROTECTED] namens Jim Rogers
Verzonden: wo 7-3-2007 16:23
Aan: FlexRadio@flex-radio.biz
Onderwerp: Re: [Flexradio] Grounding Laptop
You did not tell us much about your setup there, so this will be pretty
broad. Some likely sources of rfi
Charles,
Grounding laptops is a problem, and you have to be careful due to the
fact that sometimes there powersupply voltage on the internal ground
is really not at ground. Many laptop powersupplies do not have a
ground connection to the AC and to keep the weight down, much of the
RFI
-radio.biz
Subject: Re: [Flexradio] Grounding Laptop
Charles,
Grounding laptops is a problem, and you have to be careful due to the
fact that sometimes there powersupply voltage on the internal ground
is really not at ground. Many laptop powersupplies do not have a
ground connection to the AC
At 08:06 AM 3/7/2007, [EMAIL PROTECTED] wrote:
I have to strongly oppose your ideas on ballanced feeders Jim.
If the currents in both wires is ballanced open lines do not radiate.
If they happen to radiate that radiation is seen as loss
(loss is the difference between input and output of the
:[EMAIL PROTECTED]
Verzonden: wo 7-3-2007 18:52
Aan: [EMAIL PROTECTED]; Jim Rogers; FlexRadio@flex-radio.biz
Onderwerp: Re: [Flexradio] Grounding Laptop
At 08:06 AM 3/7/2007, [EMAIL PROTECTED] wrote:
I have to strongly oppose your ideas on ballanced feeders Jim.
If the currents in both wires
Dudley,
Tnx for the info. The power supply, like all Laptop supplies I have
ever seen, is DC, 12 volts or so. Of course the DC supply has an AC
connection, so I can add a RFI filter to that. I will try it on the
battery and see if the USB connection still drops, and with the
network
At 11:28 AM 3/7/2007, [EMAIL PROTECTED] wrote:
You are right Jim, aboud the losses,
I worked to much with UHF/SHF lately I think
Yep.. it's that darned 1 dB/ft at 30 GHz thing for coax, and worrying
about dielectric losses in PC boards, etc. Your mind immediately
springs to dielectric loss, not
Jim,
When my coax feed lines come into the house in the basement, they
have a 1:1 balun. The Windom has an air balun consisting of about 30
turns of RG8x on a 2 gallon chlorox bottle. I had big RFI problems
with another linear before the balun. The feed line for the Hustler
6BTV vertical
That sounds like a good EMI filter. Wouldn't a F-140-43 core be
better? (more turns, and better performance at HF? I don't know,
just asking).
C
At 10:19 AM 3/7/2007, Tom Thompson wrote:
Charles,
Get an FT-114-77 ferrite toroid from Palomar Engineering and wrap as
many turns of the USB
Charles,
You are correct about the F-140 because of its increased size, but the
77 material has an initial permeability of 1800 as opposed to the
initial permeability of 850 for 43 material. The 1800 initial
permeability will yield more inductance per turn , and a core with
multiple turns
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