MY CB GO BOX

[gil]

I will keep you posted!

Please do, thanks!

Gil.

[cockpitbob]

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

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):

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.

[NF822WNY]

Well as i continue to test my go box i continue to run into some problems.  I have been experiencing some pretty significant RF feedback through the microphone when TX.  Basically, after the radio has warmed up when i transmit i am getting a small shock through the microphone.  This does occur more when i am using the amplifier than when i am not.  After my initial research it appears that a grounding issue is to blame.  My question and what i can't quite come up with a solution for would be how do you ground a go box? 

[cockpitbob]

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).

[NF822WNY]

Ok, Tried everything i could to stop the RF radiation coming out of my go box.  The only way to stop it was to nix the amp....so this brings me to my next incarnation of my CB go box...Legal power ??? I want to do everything right this time and make it small and compact so i could take this literally anywhere i would like.  My question is, i am going to buy a new battery 12ah bioenno lifepo4 seems to give me good dimensions and output.  But i would like to know what size solar panel i should get.  Any brands or ideas would be great.  Everything i could find shows a 10w would work good.  I would like to panel etc to also be able to fit in my smaller box but know if that is not possible i would like a fold able Powerfilm like panel that i could also stow away.  My initial thoughts would be to use a genesun solar charge controller as well...any thoughts?

[LWolken]

If money is no object I'd get (3) Power Film 12 watt panels and a genasun controller.


vs.


Budget get a 40 watt Suakoi off ebay and a morning star sun guard controller.

[NF822WNY]

Well did some size testing, the dry box i picked up is a bit larger than expected (good thing).  I am able to fit my radio, meter, dipole antenna as well as my 40ah lifepo4 battery from my first go box plus an inverter that i picked up.  This will allow me to have a power station for cells and laptops etc.  If i go with this larger battery in the box, what size panel would i need to keep it topped off during field use?  I think i have my calculations down but not sure as this is my first dive into solar.  Here it goes:

40Watt Panel/ 12 Volts= 3.3 Amperes
40 amp hour Battery/ 5Amperes=12.1 hours of charge time approx. 

I know that there are discharge factors that would reduce this overall charge time, but then again i am only looking at keeping this battery topped off.

As far as power draw, i am going legal limit cb/ssb so 12amps max and that would be only on TX...

Does this sound like it would work?

[NF822WNY]

OK here it is CB Go Box 2.0...Spent quite a few hours putting it together, nixed the amp, secondary antenna mount, PA Horn. Changed my meter out to a new model and added power inverter to have the ability to charge some additional items Laptop Phone Etc.  I have tested this out and can also run my base station via the inverter for power down situations.  Still utilizing the 40 ah battery,  it is heavy but so much power and the price tag makes me want to keep using this thing.  Still just enough space to allow my dipole antenna some para cord and the dc charger.  Only thing i would like to add in the box is my solar controller and there should be plenty of room for that still.  I can't seem to find the perfect panel for inside the box storage, i will likely store the panel separate.

[LWolken]

12 hr charge time will take two full days with full sun and no use of the power source.  With a 40ah battery I wouldn't go less than 60 watts maybe 100 if its in the budget.  I really try to size my solar large enough to run the critical components of my station while receiving including a few hours of after dark operations.  My commo plan calls for check-ins at 12 noon, 4pm, 8pm, 12 midnight, 4am, 8am and again at 12noon.  Basically every 4hrs.  Two bands, primary for 30 min then secondary for 30 min.  You get the idea.

[NF822WNY]

Thank you for the input LWolken!  I have been thinking over 60w at a minimum.  My radio only draws 650mA on the RX with no signal, and with CB it would mostly be used to RX.  I will let you know what panel and controller i decide on.

[LWolken]

With a max output of 4 watts its not going to consume much power on transmit either.  In reality you can get by with a much smaller battery maybe 10-15ah and 20-30 watts of solar.  I like your idea of adding a small inverter and would suggest a aa/aaa battery charger also.  I like the Powerex Maha MH-C401FS model simple and effective.  If the power goes out it will be very important to have batteries for flashlights.   

[gil]

You could do fine talking to both repeaters and SSB operators without having to fuss with the antenna.

Bob, I was surprised to be able to talk to England from the French Cliffs at Cape Blanc Nez both in FM and USB with the same horizontally polarized Yagi...

As to the RF caused by the amp... I have said it many times and will continue to say it, you don't need an amp! Without the amp you also don't need a 40Ah battery! Which mean that you won't have to carry it if you have to. Using a smaller battery will also mean using a smaller solar panel. You win both in weight and money. 12W SSB is plenty of power. Some of them can also be adjusted for a bit more after the SHTF, if need be... An amp is a waste of amperes, money and carrying capacity. The only thing it might be good at is warming up your tent maybe, and at a significant cost.

Gil.

[NF822WNY]

You could do fine talking to both repeaters and SSB operators without having to fuss with the antenna.

Bob, I was surprised to be able to talk to England from the French Cliffs at Cape Blanc Nez both in FM and USB with the same horizontally polarized Yagi...

As to the RF caused by the amp... I have said it many times and will continue to say it, you don't need an amp! Without the amp you also don't need a 40Ah battery! Which mean that you won't have to carry it if you have to. Using a smaller battery will also mean using a smaller solar panel. You win both in weight and money. 12W SSB is plenty of power. Some of them can also be adjusted for a bit more after the SHTF, if need be... An amp is a waste of amperes, money and carrying capacity. The only thing it might be good at is warming up your tent maybe, and at a significant cost.

Gil.

In all honesty i have to agree without the amp the 40ah Lifepo4 is over kill.  But since the expense was already made (400$+), i wasn't going to let it sit on the shelf.  This is why I incorporated an inverter into the box.  This allows the box to be not only portable comms but also a portable charging station.  With plenty of power to run the CB, and charge things like my cell phone and laptop.