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Author Topic: what power source and modulator used ? ?  (Read 2903 times)

Offline RadioAnarchy

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what power source and modulator used ? ?
« on: September 07, 2013, 1546 UTC »
.

so what power source is being used out there for your homebrew transmitters? ?

there was all this talk about keeping them run on 12 Volts so that a battery
can be used, and bcsting from out in the woods (or desert).....
and also most have an Astron 12 V supply, actually putting
out 13.8 V, so these can be used at home.

also, what is being used for a modulator out there ?  guitars amps ?
car stereo amp?  or homebrew ?  The TDA2003 circuit ?
winding your own modulation transformer.. ? ?

also you can use your laptop computer power supply.
they are usually at 18 volts, and can deliver a few amps.
and just about everybody out there has one of these.

I am asking, since I have a few series modulator circuits,
that needs some tweaking.  But it is basically a linear
power supply, that changes output voltage along
with the audio input, as well as regulated power for the
tx oscillator and modulator audio section.  So this is
the power source for the whole system.

So is there any interest in  this out there ?

.








Offline ff

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Re: what power source and modulator used ? ?
« Reply #1 on: September 07, 2013, 1630 UTC »
Yes RA, I would be GREATLY interested in your power supply/modulator.  It makes sense to me and I would build one here to play with  ;)

I generally use 12V 7aH gel cell batteries to power my "hedgerow howlers".  Sometimes I use a single one for the peanut whistles, sometimes 3 in parallel to power the FrankenLULUs, and I'm presently trying to develop a series modulated rig that uses 3 gel cells in series for a 36 volt feed to the modulator. 

As for modulators, I generally use the TDA2003 bridged pair circuit with a mod tranny handwound on a T200-26 toroid.

I'll be starting to build your updated Guerilla design this weekend and would like to power it with your circuit.  Yes, there's interest out here...
Hailing from the upstate boondocks region of the progressive paradise which once was New York State

Offline makeRF

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Re: what power source and modulator used ? ?
« Reply #2 on: September 07, 2013, 1723 UTC »
I typically run things on 12v, and have a large lead acid battery that can be used for remote operating.  I've actually never hooked up the battery to any of my home brew transmitters, but it would work.  I've used it for remote QRP ham radio though.

As for modulation, the only thing I've used is a basic LM386 circuit.  This works well for low power transmitters, but I'm not sure if it would work on a higher power circuit.

Offline moof

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Re: what power source and modulator used ? ?
« Reply #3 on: September 07, 2013, 2100 UTC »
For your simple 10 watt deal, aint no way to go other than 12 volt 7-8 amp hour rechargeable battery. Or larger capacity.
If the builder is going to the trouble of building the amp part, they might as well build the simple modulator part as well and build for whatever input they plan on using.  Me, I like standard 1/8 inch stereo plug so you can use walkman, Mp3 player, Victrola, hell, you could could play your hour long guitar solo if you ran your headphone guitar amp into the transmitter box. I might have tried it :\  Or you can get your 1970 KMart cassette deck and run Pre-Cambian hippie noise into the thing.  No that isn't a band.
I don't do the hard mixing board stuff or line level vs headphone level.  It just needs to work with headphone output and run on a couple pound 12 v battery.

Offline Pigmeat

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Re: what power source and modulator used ? ?
« Reply #4 on: September 09, 2013, 0517 UTC »
I just bought a new gel-cell after a long run with my two old faithful's. A) The new ones are a hell of a lot lighter than the late 90's models I used. B) The price hasn't gone up that much.

There's a battery wholesaler close by that carries gel cells in different voltages. I'll wander over that way this week and see what they've got in stock and for what prices.

Offline ff

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Re: what power source and modulator used ? ?
« Reply #5 on: September 09, 2013, 1727 UTC »
I just bought a new gel-cell after a long run with my two old faithful's.

I realize that one must always take what a pirate claims with a grain of salt, but I swear on the ghost of Davy Jones that - I'm still actively using the same Yuasa 7aH gel cell that I bought new back in 1996!  Altogether I have 8 of them.  For a time I was buying 2 pulls a year from a vendor's booth at the local hamfest.  I have yet to lose any of them and have given up buying more for the time being.  I've found that if you keep them from freezing, if you don't discharge them more than about 70-80%, and if you promptly charge them up fully after use, they will last a surprisingly long time.  I'm still expecting that my battery "A" will have given up the ghost every time I go to use it, but so far, it's still good.  I don't know if the newer "lighter" ones will have the same staying power.  Don't be afraid to buy used "pulls" if the new ones will hurt your wallet too much.  You will probably be getting a battery with a lot of life left if you take care of it...
Hailing from the upstate boondocks region of the progressive paradise which once was New York State