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Messages - cockpitbob

Pages: [1] 2 3 ... 75
1
Antennas / Re: My Take on The NVIS X-Pole
« on: January 20, 2018, 06:05:19 PM »
That looks nice.  Since this antenna requires a tuner I suppose it could be used for the higher ham bands too.  Of course they would be more for DX than NVIS, but it's always nice to have lots of communication options.

I'll have to remember this one.  Here in New England we have more trees than we know what to do with, so I could leave the poles at home and throw a line over a 15' branch.

2
CB / Re: Best CB radio for inside a jeep
« on: January 18, 2018, 04:36:13 PM »
If you want more bandwidth and power, look to amateur radio. Anyone with $15 in their pocket can study a bit and pass the exam, at least Technician and General classes. Kids in primary school do it... It's super-cheap, very easy, no excuses. Ebay is littered with cheap amateur gear, often costing no more than a new CB radio.

Gil.
This^^^^
With a very simple mod (jump across 4 pads) I could wide-band my Yaesu FT-857 and (illegally) transmit on the CB band with 100W, along with all the Ham, Marine and military bands.  I haven't and won't do that, but it's comforting to know I could if TEOTWAWKI happens.

And to brag a little, my older boy got his General class ticket when he was 11 8).  He basically ground through the practice tests used that young, super absorbent brain to memorize the correct answers.  But, you do learn quite a bit when you do that.  Sadly, he hasn't been active since the hormones kicked in and girls, iPhones, etc became more interesting than talking to a bunch of grey haired geezers far away. :P

3
General Discussion / Re: Crowd Funding The Perfect Survival Radio?
« on: January 08, 2018, 10:59:20 AM »
This is the one I have.
https://robo3d.com/products/r1-plus-3d-printer
I got it 2.5 years ago mostly for my "engineer from birth" son.  I paid $850 for it.  It's print volume is 10" x 9" x 8".  Of course you can make bigger things in multiple pieces and glue them together.  Printers keep getting cheaper.  There's $250 kits that take about 6 hours to screw together that work very well(sorry I can't remember the names).

Bare in mind that there's no magic in these printers and often not a lot of difference between the $300 and $1,000 ones other than a pretty enclosure, display and no need to be connected to a computer.  They all have a heated print bed, 3 axes of stepper motors, an extruder and a controllable print cooling fan.  Most use the exact same set of Arduino boards and software to run them.  The good ones are a bit more accurate because they are stiffer.  The expensive ones use guide rods bigger than 6mm, but my printer with its 6mm guide rods does great work. 


4
General Discussion / Re: Merry Christmas!
« on: January 08, 2018, 10:51:32 AM »
Merry Christmas and Happy New Year everyone! ;D

All I wanted for Christmas was some time with the family out of the house so I could throw breakers and track down why I have S7 to S9 broadband background noise :P

I got my wish, but it didn't work out the way I hoped.  Last year when I threw the main breaker the S7 to S9 noise would go to S2 or less.  Now it looks like my neighbors are making noise too because now the noise only drops 1 to 3 S-units when I throw the breaker.  Having their noise mixed with mine will make it harder and less useful to find my noise sources ???.  Funny, but I'm looking forward to the next major power outage.  I'll run my house on my generator and the only noise sources will be mine.

It's a good thing CW gets through almost anything ;)

5
Gil, I just renewed :), a few months late.  I'm always late with this kind of thing unless I'm sent a reminder ???.  If there's any way to set things for reminders when the subscription is about to expire that will help.

-Bob

6
General Discussion / Re: Crowd Funding The Perfect Survival Radio?
« on: January 08, 2018, 10:30:55 AM »
Thanks Bob.
Just out of interest, how much does it cost to print a box?
I have a 3D printer and for the common materials (PLA or ABS) it's about $0.75/oz.  It's even cheaper than you might think because for areas of an item that have a lot of volume you tell the printer software to fill the areas with honeycomb of whatever density you want.  I use anything from 20% "infill" to 100% infill.  It saves weight, materials, print time and you lose very little strength.

Printing is a slow process.  I think printing all the parts for a uBITX box would be about 15hrs of printer time.  That's OK since it takes 5 minutes to set up a print, then I just let it run over night.

7
General Discussion / Re: Crowd Funding The Perfect Survival Radio?
« on: January 07, 2018, 03:15:30 PM »
For what it's worth, there are two 3D printable cases for the uBITX on thingiverse
https://www.thingiverse.com/thing:2745287
https://www.thingiverse.com/thing:2732866

I've made a couple cases for RF stuff on my 3D printer.  For shielding I line it with copper tape.  This makes for a very light enclosure.  12feet of 1" copper tape is only $3 on banggood.com.

8
Radio Reviews, Questions and Comments. / Re: Hambuilder review? Anybody?
« on: January 07, 2018, 02:58:39 PM »
That looks great for the price!  This really is the glory days of Ham Radio!

Give some thought to the uBITX.  It's an all HF band, 10W radio, except no box.  For $109 you get a fully tested set of boards you wire up in whatever box you want.
http://www.hfsignals.com/index.php/ubitx/.
If you know someone with a 3D printer, there's already 2 enclosure designs posted on thingiverse.com
https://www.thingiverse.com/thing:2732866
https://www.thingiverse.com/thing:2745287

If you're a builder like me, starting about a year ago I began feeling like a kid in a candy store with too much to choose from ;D

9
Joel, thanks!  Those are very reasonable power numbers.  This rig is looking more attractive every time I look at it.

10
General Discussion / Re: Crowd Funding The Perfect Survival Radio?
« on: December 11, 2017, 05:10:26 PM »
Does anyone know how much power the uBITX draws during receive?  Battery life is important and nearly an obsession in this forum 8).

11
General Discussion / Re: Hi - I'm the new guy M6UAW
« on: December 11, 2017, 02:35:21 PM »
Hi Andy,
Welcome to the board!  Welcome to the hobby!

Depending on where you are in the UK, there's a chance you and Gil (in France) could hit each other on 2m if you make yourself a cheap Yagi.  Gil has been getting into the weak-signal stuff (SSB on VHF).  Here's his YouTube on building a portable 6-element 2m Yagi.
https://youtu.be/6quIk_X3QIE

Hi guys, Just received my UK Foundation Callsign over the weekend - M6UAW. I only have FM capability on 2m and 70cm at the moment but looking forward to moving into HF comms when the finances allow.
Go see this thread that caulktel just started.  A fully built board-set for a 3MHz - 30MHz SSB & CW rig for $109!  The rig is brand new, so I don't think much is known about it, but it's done by the crew that does the BITx kits, and they have a solid reputation.
http://radiopreppers.com/index.php?topic=1384.0

We truly are in the glory days of ham radio ;D

12
Wow!  Fully built and tested surface mount boars!
Nice find.

No mention of current draw in Rx, but just looking at the board and circuitry it can't be bad.

I'd be ordering one right now, but I'm literally 3 projects behind right now ::) and promised myself I wouldn't buy another kit until I got at least 2 of these done :-\

13
Batteries & Solar / Re: MY CB GO BOX
« on: December 07, 2017, 01:54:51 PM »
Describe your antenna and feedline to it. 
My knee-jerk reaction is to put a 1:1 balun at the antenna.  You've probably got RF on the shield due to driving a balanced antenna (di-pole) with an unbalanced line (coax).

14
Batteries & Solar / Re: MY CB GO BOX
« on: November 20, 2017, 07:52:40 PM »
At a simple level I knew having different polarizations reduces reception, but I never knew any numbers.  Over at antenna-theory.com I found this little gem:  http://www.antenna-theory.com/basics/polarization.php

Quote
In general, for two linearly polarized antennas that are rotated from each other by an angle , the power loss due to this polarization mismatch will be described by the Polarization Loss Factor (PLF):
 
Polarization Loss Factor

Hence, if both antennas have the same polarization, the angle between their radiated E-fields is zero and there is no power loss due to polarization mismatch. If one antenna is vertically polarized and the other is horizontally polarized, the angle is 90 degrees and no power will be transferred.

So now I have a rule of thumb and numbers I can work with.  I love numbers ::) .  I think the equation falls apart around 90degrees because it predicts zero, but in the real world, the polarizations are probably imperfect so even if the antennas were 90.00deg off, some will get through. 

But here's my big take-away.  At 45deg the power transfer is 50%.  That's only 1/2 an S-unit.  You could cant your 4-element Yagi 45deg and its 8dB of gain would only drop to 5dB gain.  You could do fine talking to both repeaters and SSB operators without having to fuss with the antenna.

15
Antennas / Re: New Elecraft AX1 Antenna.
« on: November 19, 2017, 11:51:17 PM »
Welcome aboard Retops!  Being a QRPer and CWer almost seems mandatory to be on this board.  It's not but glad to have another!

I'm watching this too. I'm a hardcore slingshot and EFHW antenna guy, but there are some treeless peaks north of me I want to activate.  A portable vertical would be perfect.

 I too have a KX2, but mine is so new I haven't transmitted with it yet. 

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