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Messages - Lamewolf

#271
I had an enclosure that is the same physical size of my Yaesu FT-817, so I figured it would be nice to have a matching manpack portable tuner to go with the 817.  So I dug around in my junkbox and came up with all the parts to build this little Tmatch tuner that has a socket on the front panel to attach a whip antenna.  So far it will tune a 6' telescopic whip on 10 thru 40 meters and with the addition of a base loading coil it will also tune the whip on 60 & 80 meters.  The tuner will also tune coax fed antennas, endfed wires, and with the addition of a small outboard 4:1 balun, it will also tune antennas fed with balanced feedline.  I have had it on the air from my house on my 40 meter extended double zepp and the tuner matches it 10 thru 80 meters, and yesterday I had it out in the back yard on the 6' whip and worked Italy on 17 meters with it and I'm in Ohio !  Only got a 3x9 signal report, but the operator in Italy did hear me ! :)
#272
Antennas / Re: "Portable" Antennas
October 10, 2013, 03:19:16 PM
Quote from: IZ2UUF on September 09, 2013, 04:56:55 PM
Quote from: cockpitbob on September 09, 2013, 10:56:13 AM
- I carry no stakes, just one fishing pole;
- to hold the fishing pole, I have velctro ties in case I find a little tree or other suitable fixed structures; otherwise I use what I find, like stones;
- the setup time ranges from 10 to 15 minutes, depending on what kind of support for the fishing pole I find.


Davide

I just carry a big screwdriver that the handle will fit in the butt end of the fishing pole, stick the screwdriver in the ground, unscrew the buttcap off the pole and slide it down over the screwdriver.  Works like a charm !
#273
Antennas / Re: "Portable" Antennas
October 10, 2013, 01:56:41 PM
Quote from: IZ2UUF on September 08, 2013, 07:52:55 PM
Quote from: KC9TNH on September 08, 2013, 06:34:42 PM
Welcome Davide, very interesting, all the information presented. A SOTA person I've had contacts with before swears by his telescoping jackite pole, and a dipole fed with 300-ohm twin lead. He very seldom sounds "QRP" even though he is.

I really believe that: the antennae commonly used for QRP activity are so inefficient that something as simple as a dipole gives unbelievable results. The classic 30 ft "fishing pole" antenna in 40m gain is -10 dBi or less, never mind those 5 ft "miracle" sticks.

73 de Davide IZ2UUF

There is no need to worry about RF in the shack from balanced feedline, since it is balanced, the fields in the feedline cancel each other.  Coax on the otherhand is more likely to radiate RF unless some means of choking is used to keep RF off the outside of the shield, ie: current baluns, RF choke, ferrite beads.  I call the problem of RF on coax the "3rd wire syndrome", you have the inner conductor, then the shield, and then the outside of the shield that does sometimes look like a 3rd wire to RF !
#274
Technical Corner / Re: SWR Meter goes haywire.
October 08, 2013, 01:45:18 PM
Quote from: madball13 on January 22, 2013, 03:09:44 PM
I just picked up an 857 and a Z11Pro Tuner and i have a 1/2 wave 80M dipole with jumpers cut in for 10-20-40. I decided to do some testing with my tuner and with the dipole set at 20M i switch to 40, change the radio setting to PKT and key up. The radio flashes SWR as the tuner goes about finding a match. It eventually does but i notice my SWR meter is completely haywire, both needles pointing to the ceiling.

Anyone have an ideas?

I see your problem - the meter needs to go between the radio and the tuner, not after the tuner.  You want the meter to show what the tuner is doing to make sure its doing its job, so it has to go between the radio and the tuner.
#275
Morse Code / Re: 6200 miles on 3.5W and an end-fed.
October 08, 2013, 12:46:53 PM
QRP and CW does work !  I remember once making a contact to Australia and I'm in Ohio on 2 watts on 40 meters from an SW-40 rig I built from a kit.  The antenna was a converted CB vertical that I added a coil to so it would be resonant on 40 meters.  I could hardly believe my ears when the other op told me where he was, and that was over 10000 miles !
#276
Technical Corner / Re: $21 Full Function QRP tuner
October 08, 2013, 11:29:57 AM
QuoteSounds cool. Photos?

I'll see if I can get a good pic of it and then figure out how to upload it.
#277
Technical Corner / Re: $21 Full Function QRP tuner
October 07, 2013, 04:44:09 PM
Good price, but I just finished building a T-match tuner from parts I had on hand.  I had an enclosure that is almost the exact same size as my Yaesu FT-817 so it looks like it was made for the 817 and I even had room on the front panel to add a 3/8" x 24 thread antenna mount so I can put a telescopic whip on the tuner for manpack operation.  With a 6' whip it will tune 10 thru 40 meters and with an add on coil at the base of the whip it will also tune 60 & 80 meters !  Haven't made any contacts with it yet, but the weather is nice this evening, so I'll take it to the back yard and give it a try.
#278
Antennas / Re: "Portable" Antennas
October 05, 2013, 04:18:24 PM
Quote from: cockpitbob on September 04, 2013, 10:57:33 PM
Quote from: gil on September 04, 2013, 10:42:56 PM
You don't need to spend that much Bob. You can get a high voltage air capacitor for about $70, and a thick 10ft coax patch cable to use for the loop. Use a toroid core for feeding, and you'll get your Alex loop for about $100. That's what I'm going to do..

Gil.
Great!  Me too.

If you are running QRP power levels, you don't need the high voltage cap.  Google the Rockloop antenna, its made of wire with a small air variable and will work several bands, and you can make it bigger for use on lower frequencies.  Just make some sort of collasible frame for it from wood or PVC pipe and you have a portable antenna that will knock down to a small package.  Good thing about magnetic loops is that they will work well even at low heights !