Re: LF: Re: WSPR MF QRPPPPP by DK7FC ??

[schaefer <schaefer@iup.uni-heidelberg.de>]

OK, now that's the class-E version: https://dl.dropboxusercontent.com/u/19882028/MF/20140223_223105.jpg

The PA input power is now 2.5V * 23mA = 58 mW, so maybe 40 mW RF power

The drain source voltage looks quite good, so i assume the efficiency is above 70%. Due to the low Q of the fixed inductors the result is however not as good as it could be. Anyway...

I'll let it run over the night, and i will remove the 100 Ohm resistor, so the power will rise now and will become lower and lower until the battery is completely empty :-) Let's see who makes the last decode :-)
Actually i nice game for using empty batteries which have some rest energy.

73, Stefan/DK7FC


Am 23.02.2014 20:09, schrieb schaefer:

Hello Andy,

It is sunday so it is a bit harder to find a lemon if you don't have one at home :-) Thus i'm still using the empty 9V battery, which has 2V now again. The power consumption of the PA seem to have dropped. Anyway the voltage across the 50 Ohm BNC jack rose! Seem the efficiency is much better now :-) And the voltage form looks much more sine like :-)

73, Stefan

PS:. About the 1W, i'm not using K1JTs software to generate my WSPR signal but the software by DF6NM. This has a fixed "message", i.e. parameters. It is because WSPR-X is a "dial" software, so i would have to use another VAC line if i want to use it. I already need 2 VACs for LF/MF WSPR RX. So just ignore the 1W. Normally it is not 1W anyway :-)


Am 23.02.2014 19:58, schrieb André Guyé:

HI, HI Stefan.

 

A nice image, but where is the lemon High voltage battery ????

 

I wish you a lot of fun. On the way, can you correct your power. You sent 1 Watt / 30 dBm, that is a bit too much indeed ! HI

 

Andy.

 

From: schaefer

Sent: Sunday, February 23, 2014 7:50 PM

To: rsgb_lf_group@blacksheep.org

Subject: Re: LF: WSPR MF QRPPPPP by DK7FC ??

 

Hello Andy, MF,

Here is an image of what i have so far: https://dl.dropboxusercontent.com/u/19882028/MF/20140223_193945.jpg
I'm just playing arround, without having a schematic or calculations. But now i'm starting to add some elements to improve the efficiency.

Maybe tomorrow i will transmit with a LEMON. Maybe some JT9 or WSQ QSO can be made with that ;-)

73, Stefan



Am 23.02.2014 19:25, schrieb André Guyé:

Ok Stefan,

 

here hard to copy you because your TX frequency is not clear at this moment.

 

Please, what is the current intensity at the base of the antenna ?

 

Andy.

 

From: schaefer

Sent: Sunday, February 23, 2014 7:08 PM

To: rsgb_lf_group@blacksheep.org

Subject: LF: WSPR MF QRPPPPP by DK7FC ??

 

Hello all,

You all know me as a QRP station :-) But today i want to run even less power!

While running in the sunny afternoon i got the idea to build a very small and weak PA. After some playing arround it came to me that it will be a class-E PA. The power supply should be a lemon battery, i.e. a homemade galvanic element, maybe 2 in series!

The desired RF power is arround 20...40 mW, at 2 V DC. And i'm using a BS170 MOSFET for that PA. The biggest part will be the BNC jack :-)

So far i'm testing with an empty 9V battery and a 100 Ohm resistor in series. I measured 2V and 35mA. But the PA is not yet aligned for class E mode. Probably the efficiency is less than 50% in the moment.

Anyway several stations seem to copy me :-)

More reporting stations are apprechiated, if you like to test your sensitive RX :-)

73, Stefan/DK7FC

PS: Later, i want to try to rectify some RF coming from AFN to my antenna. It this is fed to a 10F gold cap and WSPR-2 in 33% ratio is sent, maybe i can run that PA from the energy of AFN :-)

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