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Messages - cockpitbob

Pages: [1] 2 3 ... 68
Tactical Corner / Re: All Weather Shelter for Field Communications
« on: August 07, 2017, 06:18:57 PM »
I used to go backpacking in the New England states in winter.  The one thing I learned, and it seems to be a universal rule for those that winter camp, is either get the proper gear or don't do it.  Without an appropriate tent, sleeping bag, pad/mattress, boots, clothes.... it's at best miserable and risky. 

That TipiTent looks interesting, but not having a floor is disqualifier for me.  Between bugs and critters having access when not on snow, and that a high wind could get under the edges.  Ohhh, but to have all that room and a wood stove would be luxury!

Antennas / Re: The PAR OA144 2m Omnidirectional Antenna.
« on: July 24, 2017, 02:55:50 PM »
Nice vid Gil.

I see what you mean about the U-bolt not having threads that go down far enough.  Of course you always have the option of using a stack of washers under the nuts.  I had to do this once and I glued the washers together so I wasn't always fumbling with them.

At first I thought it was a Moxon and wondered what the Omni part was since a Moxon has a big front-back ratio.  I never gave much thought to the difficulty of doing a horizontally polarized omni, but it can't be done with something as simple as a ground plane vertical or J-pole like you can use for a vertically polarized omni.  This is clever, and small.   Then I thought "I wonder how hard it would be to convert it to a Moxon.", but I looked it up but the square pipe would need to be about twice as long. 

BTW, in the background I think I see several masts ranging from about 3M to 6M tall on houses.  Are there a lot of radio operators there or are they for TV or something else?

Antennas / Re: Trapped EFHW info
« on: June 30, 2017, 10:40:00 PM »
Hi Joel,

I used 24AWG insulated wire and the higher dielectric constant of the insulation slows things down just a bit so yes about 63' for 7MHz and 14MHz will resonate at that length too.

You'll need a "coupler" (49:1 or 64:1 transformer) but not a tuner.  Trim for resonance at 14MHz and 7MHz will be fine.  14MHz is fussier about length because the waves are 2x shorter.  I like the wide-band transformer type couplers like LNR precision's since there's no variable cap to have to adjust.

Antennas / Re: Building a Portable 6-el. VHF 2m Yagi-Uda Antenna.
« on: June 30, 2017, 09:42:52 AM »
Thanks Bob  :)

I remember you were inquiring about aluminum solder, but I didn't see anything that looked like 2 pieces soldered together.

Well, that's because it didn't work :o The reflector is missing 3cm... I taped the piece on for now, but I need to find a way to permanently attach it with a good electrical contact.

Could the rod have anodizing that needed to be sanded/filed off?
I've always wanted to solder aluminum but never put any time into that.  I've seen a salesman demonstrate aluminum soldering at a car show and it looked pretty simple.  I wish I had bought some rods to try.
In a class I learned to gas welded aluminum (oxy acetylene) and it's tricky as hell with everything needing to be clean and all oxide removed.

Batteries & Solar / Re: And the winner is...
« on: June 29, 2017, 09:25:23 AM »
Maybe it's so hot there, this is where the cold water side of the faucet comes from

Antennas / Re: Building a Portable 6-el. VHF 2m Yagi-Uda Antenna.
« on: June 28, 2017, 11:04:52 PM »
Nice.  And I liked the music.

I like the simple, take-down design with the clothespins.  I couldn't quite figure out what you were doing with the propane torch.  I remember you were inquiring about aluminum solder, but I didn't see anything that looked like 2 pieces soldered together.

Antennas / Re: Chameleon PLOOP 2.0.
« on: June 25, 2017, 10:28:42 PM »
I made one similar to the P-loop with an air variable cap, LMR400 for the radiator and RG58 for the little loop coupler thingy.  I had very little money invested in it, but I won't put more than 10W into it because I don't trust the air variable that much.

Pro-tip:  I mounted the loop coupler thingy so I could slide it up and down and vary its distance from the main loop a little.  With that extra adjustment I was able to get a true 50, j0 Ohms impedance.

Antennas / Re: Trapped EFHW info
« on: June 25, 2017, 10:22:34 PM »
One additional comment on trapped EFHWs.  That 40/30/20 antenna I made is super convenient, but it doesn't perform as well on 20 as my 63' long wire.  The 63' wire is resonant on 40 and 20, so on 20 my antenna is 63' long, while with the trapped antenna only uses that first 32' piece of wire.  20 has half the wire in the air, and it's lower to the ground.

General Discussion / Re: Field Day
« on: June 25, 2017, 10:14:24 PM »
I'm a busy dad and had to skip Field Day this year, but it's been interesting watching the club's approach to it morph over the years.  A few years back we did the full deal:  6M tower, vertical and wire antennas.  Several tents, pop-ups and 2 car-ports.  Local Wi-Fi or mesh to link the computers together for coordinated logging.  GOTA station with literature displayed and banner by the road.  "Food and drink" crew with bbq grill.  Local politician stopping by.  After pre-setup Friday night a movie projected onto a white tarp.  We had people designated to hit a satellite, capture the ARRL's broadcast message, make some QRP contacts etc, etc, etc.  After a while we got tired of all that.  I mean literally physically exhausted.  The set-up and tear-down got to be too much, especially in the years with really hot weather or the year we had a down-burst relocate several tents leaving their poles bent.  The last couple of years Field Day has been in the club house with a generator and solar panels out the front porch ???.  The focus now is 100% on fun and socializing ;D.  Screw trying for points.  We used to have operator schedules for each station, but now it's work 'em if you want, or sit around and talk if that's what you want.

Edit:  Here in Massachusetts today it was in the high 80s with 85% humidity.  It's 10:20pm and raining now.  I'm kind of glad I skipped Field Day this year ;)

VHF and Above / Re: VHF SSB for Local/Regional Comms? And IC-251E...
« on: June 21, 2017, 04:22:25 PM »
I wish I could find that article where Boy Scouts were camping and doing 2M work.  They made a 3 element Yagi with a tree branch and some barbed wire and talked off a mountain top repeater many miles away.  The rusty barbed wire on the crooked stick looked awesome.

Antennas / Re: The SotaBeams Valley Tuner on 80m.
« on: June 19, 2017, 09:41:12 PM »
The link for the Valley Tuner doesn't work and I can't find the Valley on their web site.  I think they discontinued it :-\

Gil, do you know if it uses the same variable cap as the Mountain tuner and just more transformer inductance?

Antennas / Re: Trapped EFHW info
« on: June 12, 2017, 11:15:42 PM »
Like Ray said, a 66' length of wire will work on 40 and 20.  It will also work on 15 meters since it is 1.5 wavelengths long at 21MHz.  That's the beauty of what our founding ham fathers did.  Many bands are harmonically related.

Check out  He sells a line of EFHW antennas that are multiband with one piece of wire and no traps.  His secret sauce is the wideband transformers in the match box.

Traps are good if you want 30M capability.  I made a 40/30/20 EFHW using 20M and 30M traps.  Cutting the wire is tricky.  Here's the process I used.
1. Hoist just a 34' piece of wire into the air and trim to 20M. 
2. Attach a 20M trap to the end and add 13' of wire, hoist back up and trim the new piece to the 30M band.  Expect to trim a lot off since the current flows through the trap's inductor which acts like a loading coil, so the overall length will be shorter than the expected 468/10.1MHz.
3. Attach the 30M trap, add wire and trim the new end to the 40M band.  Again, the added wire will be shorter than expected.

Note that the traps must already be tuned on the bench to the desired frequency.

Technical Corner / Re: The $4 Chinese Pixie Transceiver.
« on: June 06, 2017, 09:40:04 AM »
The New England QRP Group has their audio filters available starting June 8.  I still haven't built my Frog Sounds or Pixie, but have ordered some 7,030 crystals and will be getting the filter kit (in case they sell out quick).

General Discussion / Re: Anything interesting going on?
« on: May 11, 2017, 09:51:15 AM »
When I get as chance I'll take some photos and post in the Technical forum about how I used a $6 eBay Bluetooth receiver to tie into the planes intercom system to stream aural alerts from my iPad - and iTunes :-) It's not  ham radio but it could be and some may find it interesting.
Please do!  I'm interested.  I mainly design analog electronics and I've not kept up with how cheap and plug-n-play lots of the digital stuff has gotten. 

General Discussion / Re: Anything interesting going on?
« on: May 11, 2017, 12:06:30 AM »
Guilty here too.  Work, wife, kids, house... life.  Work is over the top right now with 3 projects behind schedule and in the home stretch (short strokes), and I'm involved in all 3.  I've done almost no operating this year. 

One thing competing with ham radio is marksmanship.  I'm back to shooting and reloading regularly. 

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