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Author Topic: Higher power design.  (Read 3928 times)
redhat
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« Reply #15 on: January 13, 2016, 1240 UTC »

I always like to look at the whole package, you never know what someone may try to hack up.

Just because it's in a rack doesn't necessarily mean it's indoors.  My TX lives in a road case and spends quite a bit of time with nothing but stars over it Smiley

Battery power is appealing if your operating from somewhere where you are not necessarily welcome, someone's field for instance, or back parts of a park.  Generator power in these instances, even with modern inverter type generators can raise the 'here I am' flag, as if a tall antenna didn't say it already.

+-RH
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Stretchyman
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« Reply #16 on: January 13, 2016, 1313 UTC »

I'm trying to keep costs to a minimum. I wont be supplying any power, just 'recommendations'.

It will need 110-120V A.C. (or D.C.) and 24V (probably) as the drivers need 18V.

Also I'm not that interested in selling built units, one or two maybe to 'notables' but no more.

The kit will be fairly simple to put together.

 Smiley

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ff
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« Reply #17 on: January 13, 2016, 1317 UTC »

Very interesting thread guys but I've been lurking because the subject matter is mostly above my skill level.  I think you're on the right track by designing for a less ambitious power level Stretchy.  Feedback I've received over the years from homebrewpirateradio group members who value portability do so for TWO reasons.  First of course is the security of being able to transmit from - WHEREVER.  Secondly, many ops live in:

Trailer parks
Apartment Buildings
Dense Subdivisions

All these situations find the op in very close proximity to neighbors and all their poorly-filtered consumer electronic devices.  The 10-20 watt carrier level minimizes bleed through problems and yet works quite well for NVIS mode operation, which is what a typical sub-optimal antenna is best for anyway.  I agree with Redhat - generators are a bust.  Even the quietest are so damn noisy that you need to be surrounded by many many acres of nothing or you'll be attracting the wrong kind of attention.   I'm guessing that you'll find some takers for a 100 watt carrier level transmitter.  Good luck with it...
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redhat
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« Reply #18 on: January 13, 2016, 1326 UTC »

It is true, battery operation above a certain power level begins to get ridiculous, and that point seems to be 100W-250W.  Above that, generators or shore power are the logical choice.

+-RH
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WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com
Stretchyman
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« Reply #19 on: January 13, 2016, 1716 UTC »

You can series the batteries so you get 24V or 48V (or whatever) and invert to a higher voltage from there.

Yes gennis are noisy and not advocating their use (altho' I would as I have a site miles from anywhere) and am just trying to cover as many bases as possible.

The (RF/PWM) design will (should) push close to a KW (@ 150V) and of course will need many volts hence my 120/150V supply.

However it will work at ANY voltage, half the volts = quarter of the power.

 Smiley
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Stretchyman
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« Reply #20 on: March 17, 2017, 1023 UTC »

OK, Have a working design, at last!

24V = 100W so 48V will yeald 400W.

The design was built with much higher voltages in mind (150V) but have obtained decent efficiency (88%) at this relatively low voltage.

Using a higher voltage I expect 95% efficiency.

I have a PWM modulator or conventional Audio amp and mod tranny to use as modulators, PWM needs twice the voltage as conventional method.

Check out attached image.

Str.


* amp setup.jpg (125.34 KB, 1116x724 - viewed 40 times.)
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                            Buy one from me, NOW!

Great discounts on ALL my transmitters if purchased via HFUnderground


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