1 Volt QRP Transceiver

1 Volt QRP Transceiver

Members of the DL QRP group are involved in a project to build a QRP transceiver that runs on just 1 volt.

The goals of the project are:

- Save the resources of our earth, save the earth
- Reduce battery waste
- Reduce required materials
- As much fun as possible, so make a real useful transceiver

Details of the project have now been made available on the web. The article says:

"Modern solid state technologies makes it possible to design RF transmitters and receivers with a powers supply as low as 1 Volt with good efficiency. The mainly power consumpting parts, the AF end-amplifier and the RF-PA have to be designed very carefully to give good results and to meet the goals. The efficiency today would be optimal at 3 Volt. This experimental design will be the base for a 3 Volt Transceiver with an RF power of > 0.5 Watt."

Read the full article with circuit diagram at http://www.lichtnetzwerk.de/1volttxvr_dkumentation.pdf

DL-QRP-AG
http://www.dl-qrp-ag.de/







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Just knew if I held on to those 1v cells long enuff someone would find a use for them. I may have the market cornered. Offers?

TOM K8ERV Montrose Colo

 

check out the August 1992 QST.It has a lemon powered(homemade lemon batteries) transmitter.Since power out and band is not specified(that was for 10m) , I guess they just found a TX.

I think the main problem would be current.Those 1.5V AA aren't rated for a lot of current, which means they would die within a few minutes.

Thanks to the DL-QRP for this innovative project idea.

73 de va7aax

 

Perhaps a better goal would be a specific amount of efficiency from a transmitter.

If the real goal is to "save the earth" (as if it can't take care of itself ), try using a hand (or foot) cranked generator for the tx and a crystal rx that doesn't need ANY batteries.

This whole thing just sounds very unfocussed to me.

(BTW a VX-7R can get by with 3 volts and 300mw out, at least it's nice to know the goals they are aiming for should be achievable).

I'm all for radio projects that get people going though.

Joel

 

From the figures they give, a single AA alkaline cell should last for many hours of constant use. The highest current draw given is 330mA.

At an average draw of 300mA, an AA cell should last about 8 hours of key down time, assuming it wasn't all at once. Figuring that CW is about a 25% duty cycle when actually operating, that would translate into 32 hours of operational time.

100+ mW of CW power on 20M should garner some contacts. It is a very interesting idea, and well done.

Joe

 

I think QRP ARCI had a contest to tackle the issue of using a single 1.5v battery to power a rig as well. I'll have to dig in my back issues of QRP Quarterly. Anyone else remember that?

 

In the interest of efficiency......

Aside from Chuckle's chuckles, have our friends thought about CE or DS efficiencies? By lowering the input voltage, the rather fixed Vce or Vds saturation drop becomes a larger percentage of the power supply. Hence lower efficiency. And, I don't care if its class A, AB1, B, or C.

Lowering the power supply rails makes sense if all you're doing is switching, but amplification is another ball game.

Better to have the higher voltage since you can use more of it in developing desired output power. Or, the voltage drop losses become less significant.

That is, if the intent is to improve efficiency, save the lemon or aluminum can supply or whatever.

73.

 

Thats exactly what I thought. Probably can make a more efficient radio with more output simply by using two (or three) AA cells instead of one. Would make a very small change in overall weight.

But I think the purpose here is to show what can be done with one cell, and it accomplishes that goal.

Transmit efficiency is .33 x 1.5 = .495 watts in to generate .18 watts out, or 40% efficiency.

Joe

 

Not to belabor the point, Joe, but input power would be 0.33 X (1.5-VceSAT)
if a bipolar final amp stage. If VceSAT is a typical 0.1V, that's significant.

Based on your calc above, I didn't get your result. I got 0.198W, assuming 40% efficiency and not including VceSAT. 0.18W would be 36.3%, if my calculator's right.

If you include a VceSAT of 0.1, output is 0.185W.

Assuming two cells, and halving the current, 0.165 X (3-0.1) = 0.4785, with the same VceSAT. And with 40% efficiency, a net of 0.191W.

A net improvement of 0.006/0.185 or 3.2% by having the higher power supply voltage. Not much, but it might make someone grin......

But, who knows, maybe the extra weight is a factor. Of course, not for Flying QRP Pigs.

 

I'm talking about overall efficiency, and it's probably more like 36%, not 40%. Don't know where I got 40% from, must have input the wrong number.

On battery operation, the overall efficiency is really what matters most, since that is the bottom line. But it should improve dramatically as the voltage increases.

Still, having a single AA battery power any sort of transceiver for several hours is no small feat.

Joe

 

1 Volt QRP!— And To Save The Planet for Whom, exactly?

But on a similar but technologically more appealing note for the level headed amateur or 'ham' there is a very readable construction project for a Ikhz receiver, in May 2008's 'Practical Wireless'. I checked it out in a High street bookshop today, but settled for a copy of Micromart in the end.

"QRV on 1kHz Fancy a receiver for the 1kHz band?"

The full design by EI3CY uses thousands of turns of ultra-fine gauge wire on I guess, a ferrite rod and gets a great review. EI3CY says to the effect that he has no qualms with constructing radios for off-amateur bands since he is licensed to conduct radio experiments.

Save the Earth for whom, I wonder? That should be an adjunct posed for every far-fetched claim on the now hijacked issue of environmentalism. I once fitted, along with my then pals WA4PVQ and WA4BWR, amateur radio gear on the Rainbow Warrior, flagship of Greenpeace for family to crew phonepatch 'ship-to-shore', long before the advent of Satellite, back in the day when saving the planet meant, stopping Japanese medium level reactor waste being dumped 500mls off the Cornish Coast in the Atlantic, or actually saving the whales.

Come on y'all! When the UK is about to adopt a whole new generation of French built Nuclear Power stations on the pretence that this is now classified 'a renewable', a shortage of electricity and the need for 1V Txcrs is not an issue we have to be distracted by, is it? Move on up, I got a Legal limit 2×813 Linear to get built in the shack here.

73

 

It was actually very useful to post the reasons for the project, if they are looking for maximum effieciency, why tie themselves to 1 volt, for all of the reasons stated, if they are looking for enviornmental friendliness, why use batteries at all instead of a manual generator.

It's frequently important to define what an objective is. Right now they seem to have conflicting ones, an input from the original poster would be useful explaining which they are most interested in. The best efficiency per weight, or maybe minimal use of consumables, either way it's obvious that the people here have been helpful on the technical aspects.

 

Graeme:

Perhaps 2X813 glass envelopes will develop legal limit power in the UK, but not across the pond.......

Now, 2X4CX1500 ceramic tetrodes would do it just fine and loaf along. And, you wouldn't have to operate inefficiently and ground their grids.

 

To be honest with you, im happy the thread went right back to being a simple ham radio technical discussion. Please, carry on.

 

LOL! Alright. First off, I am not out to flame anybody here. Just have fun. If someone wants to build a 1 V transciever for the sake of building a 1 V transciever, go for it! Have fun with it!

Ron, I hate to break the news to you; but you will not be able to find your gas burning transciever. I drove my gas guzzling SUV over to your house; used a gas burning 2 stroke chainsaw to break through your door and stole your gas burning transciever. Oh yea, and then I sped off in my gas guzzler exceeding speeds over 55mph so as to not conserve fuel.

73
John
oh yea. Peace.