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Yes, many use 31 material for this purpose. I've wound many like CM chokes using red cores, 31, and 43 material. Problem is with the higher ?r materials, I end up with a virtual tesla coil at the

"The impedance of a helical antenna is about 140 ohms. To match that to 50 ohms, you can use a quarter wave of transmission line of sqrt(50 * 140) = 84 Ohms." Dr. Kirby, I'm trying to get my head

ps.: select: ST7796 touch -- *** If you are not part of the solution, then you are the problem. ( http://ha3hz.hu/ ) ***

Hi Jos, read this message: /g/nanovna-users/message/16521 -- *** If you are not part of the solution, then you are the problem. ( http://ha3hz.hu/ ) ***

I have excellent results operating NanoVNASaver remotely via VNC from my iPad (and iPhone for that matter). I have not tried it with my Android pad, but since I use VNC clients from the same

Part of the problem could be that you seem to be using a Red type 2 low permeability iron powder core. This will not provide a high enough value of choking impedance for the purpose you wish to use

Dave, Thank you for those clear photo's and measurements. From the Smith charts I think we me conclude that the windings (forming a 2 wire transmissionline) have a Z0 of about 100 ohms. The enameled

Dave, I had some 18awg coated solid copper wire i stripped form a piece of thermostat wire and managed to get 16 loops onto the core. I am 3d printing a centre insulator for the two wires form the

Bob, I do understand the antenna is low to the ground to go any higher i only have one option and that is to slope the wire from the 2nd floor of house so around 25 to 30 feet down to the back fence

Is this the antenna which is 6 feet (1.8m) above the ground we are complaining about? What can one expect with such a large capacitor to ground. Let's get back to basics. Pre VNAs. The most

helix antennas I have built a few for L band and they work. Decoding Inmarsat and AERO around 151East. Can't wait to get my NanoVNA H4 so I can test it to see if building it agrees with the

In the write-up, the last 'subject' was professionally done. Notice it consists of 16 turns of AWG #14 solid copper wire wound in a bifilar manner. This one measured the best and is the size of the

Attached are the measured data sets for the CM chokes I illustrated in the previous email plus a couple of others Dave - W?LEV wrote:

For the doublet which consists of two roughly equal lengths of wire each side of the center insulator, just wind yourself a common mode choke. It will serve very well as a balun as it will discourage

Thanks for the detailed explanation of the graphs I could certainly follow it on the graphs. I have 2 of the T130-2 cores but the only mag wire i have measures 1.90mm across which is way too heavy

No.....NO.....N O.....!! Something is wrong, here. Look at just the Smith Chart! Open shows lots of loss. Short shows very high Z. 50-ohm termination shows high Z and totally inductive. All

so if the balun is good how can the wires themselves be bad? I would have expected this ant to be usable across the band windcamp advertised it to work at 5-50Mhz but it seems in most cases my

From the plot with 50 Ohm resistor you can see, that the balun is good (VSWR < 1.5) from 3 MHz to 30 MHz. The other plots are unimportant. But remember that an antenna with bad VSWR will also give

Thanks Larry, yes I thought to remember that and searched the forum using "H4 LCD screen" etc. but no luck. Will try again using his name for the search. Best regards, Jos Op 5-11-2020 om 18:35

I decided to test the Balun itself maybe someone can help me read these plots. I have one plot with the ant lead of balun open, shorted and with 2 100ohm resistors in parallel that read 49.9 ohms on