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Topics - gil

Pages: [1] 2 3 ... 21
3
Antennas / Do NOT Leave Your Antenna Plugged-in.
« on: May 23, 2017, 03:43:14 AM »

Gil.

4
Technical Corner / Easy Dummy Load Project.
« on: May 22, 2017, 09:37:44 AM »
Hello,

Here is an easy project involving a BNC connector, small plastic box and eighteen 100-Ohm 2W resistors. Total resistance is of course 50-Ohms. What is the total power handling?  ;D



Gil.

5
General Discussion / QRP Night, seems like a good idea...
« on: May 18, 2017, 12:58:33 PM »

Gil.

6
Digital Modes / Digital Modes for Prepping.
« on: May 16, 2017, 04:03:39 AM »

Gil.

7
Technical Corner / Surface-mount components and toroid winding.
« on: May 10, 2017, 12:50:33 PM »
CC from the BITX20 group:

I never understood why some kit builders are afraid of either. To those who have never tried: Unless you no longer have a steady hand or your vision can't be corrected, SMT kits are no harder than through-hole kits and in some regards are simpler. You don't have to cut any leads. I built all my surface-mount kits with a fine tip soldering iron and they all worked. Some had very tiny integrated circuits. All you need is a good magnifying lens and no shakes. It isn't magic. The biggest difficulty is when you lose a component on the floor!

As to toroids, it's the easiest thing in the world. If you can count you can wind a toroid. Thread the wire through, that's a turn, repeat until you reach the prescribed number. A four-year-old can do it. Even taps are a piece of cake. I don't know where this fear comes from... It must have been spread somehow and people believe they can't do it.

Of course some people have physical limitations, but otherwise, those fears are unfounded, especially for toroids, I'll always scratch my head about that one... Winding toroids is probably the easiest part of kit building for me, by far.

Gil.

8
General Discussion / Anything interesting going on?
« on: May 10, 2017, 03:57:43 AM »
Hi, is everyone hibernating? Nobody is testing gear, operating outside, coming up with new ideas worth posting? If not I hope you are at least sharing this site... We need some action here :o While I'd rather keep this community small with quality people, 287 members is a bit low... I also have been the main poster lately... We all need to contribute to keep this place open. Thanks!

Gil.

9
General Discussion / Praise For The 80m Band and NVIS.
« on: May 09, 2017, 07:16:53 PM »
Hello,

Since I put up my 135ft Windom things have changed a bit, especially how I view local to regional communications... First with England. I am now able to reach several British locations on the VMARS net every Wednesday night on 3615 USB with my RT-320. The propagation isn't always good but I can usually make contact with at least one station, often three or four. The range seems to extend as far South as Italy from the North of France. I just had a QSO with Italy, another one with Germany near Lake Constance, nice chat, not just 5973. Then I hear ON7YU, still on 3560, only 90 miles from my location. He's running a K3 using 1W. For fun I lower my power to 500mW, then 100mW... My RST stays the same. He lowers his power to 100mW as well, same result. We continued a nice chat using 100mW CW on both ends. It's not line-of-sight, so QRPP NVIS (Very Low Power Near Vertical Incidence Skywave) :o for sure.

When I tested the W3EDP antenna, strung horizontally, using the PRC-320, I noticed very high reports on the Reverse Beacon Network, one at 36db over noise. NVIS rocks! Low power NVIS was a nice surprise. Ray had told me about it, but experiencing it is another story... There is a catch of course, the 135ft wire... That said, since it is horizontal, you don't need to put it very high. My Windom is only about 7m off the ground. Probably the reason why I can't get any DX out of it. My longest DX so far from here has been the U.S. using a 2.5m vertical whip!

My take on polarization now is to use verticals for 30m and above, horizontal for 40 and 80m. I'll use a vertical on 40m again when we climb up the solar cycle.

I will do more testing with 80m NVIS portable. It sure beats UHF which usually only works for 10-30 miles. With NVIS I basically rain RF on a 1000km radius. Right now it's still a bit cold out at night but it will be interesting to test 80m at night, clandestine portable style 8) I also plan on making the super gain 40m NVIS antenna I recently posted about:

http://radiopreppers.com/index.php/topic,1260.0.html

Even a tiny 80m QRP rig like the 1-Watter could be a viable bug-out bag radio. A thin 135ft wire and small end-fed tuner doesn't take much space and only needs eight AA cells for power. Those recent contacts certainly motivate me to box up my 80m 1-Watter, which works now and is waiting to be mounted in its Hammond case.

If I had the money right now I'd build a 40/80m K1, the ultimate NVIS machine! Long antennas are a pain but aren't impossible to use for portable operations. With decent band conditions, a wire only a few feet off the ground will work. Add reflectors and you even get some gain...

If you hesitate you give 80m a try because of antenna length, do it anyway. It's like having a regional telephone ;D

Gil.

10
Net Activity / VMARS Net, France to England.
« on: April 26, 2017, 04:24:02 PM »
Hello,

I have been participating in the VMARS (Vintage & Military Amateur Radio Society: http://www.vmars.org.uk) for a while now Wednesdays at 20:00Z on 3615KHz. My 135ft Windom at 20ft is great for NVIS to England. Great people there, all interested in military radios. The net is in USB since many green radios do not have LSB.

That's what radio is about, building relationships, not 59-73 contacts.

80m turns out to be a great band for regional comms and I am glad I built the antenna for it.
See the last page: http://radiopreppers.com/index.php/topic,1096.0.html

Anyone within a few hundred miles please tune in! I always wait a few minutes after the net in case someone calls...

Gil.

11
Antennas / The Best Antenna Video EVER!
« on: April 26, 2017, 12:43:10 PM »
https://youtu.be/LEigIMS6bo4

It sure gave me a new appreciation for the inverted V. It also clearly shows that putting a dipole high enough to get a good low angle radiation is very difficult and that verticals are best for DX, horizontal dipoles for regional comms. It's one think to know it, quite another to actually see it!

Gil.

12
Technical Corner / Armored BitX40.
« on: April 24, 2017, 12:32:12 PM »
Hello,

I have been playing with military radios this year (PRC-320 & PRC-351), which gave me a new appreciation of what ruggedness really means. I won't duplicate the toughness of those radios, but I think we can do better than off-the-shelf amateur gear. Ray did it with his "up-armored" KX1:

http://radiopreppers.com/index.php/topic,897.msg8887.html#msg8887

I want to do something similar with the BitX40. Hopefully I can also modify it to do USB and CW.

The case will be the cast aluminum Hammond 1550G. It has a gasket for water resistance. I have used these Hammond cases for numerous projects and they are awesome and very though.

I will use DDS for the VFO but no screen and no rotary encoder; too many holes... I want the case to be watertight. So I opted for this military surplus (NOS) keypad:



I will also get a U-183/U audio socket to plug in an H-250/U military handset. The microphone has an impedance of 150-Ohm, 1KOhm for the speaker, so some modifications will be needed.

The difficulty will be to find the pin-out schematic of the keypad and program the Arduino board to update the DDS chip. I want to use direct frequency entry but also up/down scanning of the band. There are enough keys there to do everything, though of course, the markings will be off.

The only connectors on the case will be the BNC antenna socket and U-183/U audio socket. I want to use one pin out of five to turn the radio on so that it will be on when the handset is plugged in. Batteries will be three, four or six 18650 cells. I might add a charging socket but it would have to be a watertight military model, otherwise all my other efforts would be for naught.

The BitX40 and keypad are on the way but I am broke now, so you will have to wait a little for the next post :)

Gil.

13
I'll henceforth carry a whistle when using voice-only radios!

Voice did not go through but voice-Morse did! Never thought of doing that and though it's laughable, it gets the job done. Just hope there are no passer-bys,  :o


Gil.

14
https://www.kickstarter.com/projects/hobbypcb/rs-hfiq-5w-software-defined-radio-sdr-tranceiver

From the makers of the Hardrock 50W amp... Pretty interesting and affordable...

Gil.

15
Antennas / Building a Slim Jim for 6m.
« on: April 21, 2017, 02:42:01 AM »

Gil.

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