Repairing an Pixie QRP with blown up PA.
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- čas přidán 28. 07. 2024
- My chinese 40m Pixi transceiver was broken. I connected 13.8V and a antenna with SWR 1:1.5. The finals blown up. So I show the replacement of the finals from S8050 to 2N2222. It worked nice but finals blow up again on 13.8V. So from now on only 12V or less. This seems to work stable.
There will be a kit building video of an fourty-9er and after that a comparison between pixie and 49er.
The video quality is not perfect. I used a GoPro but too close. Next time it will be better 👌 - Věda a technologie
I use a socket with my PA transistor on my Pixie. The 2N2222 works very well with 12 volts and good swr
Looking forward to seeing the 49er build.
Mine blew up and as I tired to repair it the copper track lifted. Good while it lasted on 5.262 MHz.
My new one has a fault on the track, when the audio jack plug was inserted it shorted out the audio. I removed the socket to confirm it and destroyed the socket. The track needs cutting, check before soldering the socket in place. There seem to be a few manufacturers of Pixie's.
G4GHB.
you need a transistor with a higher Collector-base voltage.
eg the BD139
Do we get a couple of watts using BD139 as a PA transsitor?
Hi,
Cannot we replace the PA transistor with a more powerful RF transistor, like BD139, or even better to get 1 or 2 watts out?
Hello, have you tried adding heatsinking to the 2N2222? Would the transistor blow even without any keying at 13.8v? thanks
The transistor dies during transmit. Receive on 13,8V is no problem. I added no heatsink but I bought the 2N2222 with metal chassis. It seems a little bit more stable. But 13,8V still not possible. I operate the Pixie now using 8x AA cell. This works fine and output is about 450mW. Thats OK. I think on 13.8V the max thermal power of the transistor is exceeded. 73
Hi,
my Pixie died just connecting a 13.5V, without any transmission. Coud be the same problem you had?
Thanks for your job!
Hey. I know it’s a long time ago, I bought a couple of these for my son to put together. They had a 1A bridge rectifier so you couldn’t accidentally reverse polarity the unit, however, I have popped these a couple of times, with one of the diodes going short
The CSS8050 isn’t a bad transistor to use for the output, and it will handle over a watt
I also replaced the CSS9018 small signal transistor, used for the oscillator with another 8050 to get close to a watt out on 13.8V to the circuit by using 10x AA batteries to feed 15V into the unit less the 0.6V dropped over each of the diodes in the reverse pol’ protection
There’s not much to these, so easy enough to troubleshoot with a meter. Trickiest part is desoldering components without damaging the board
I'm having other issues... Not sure what I did wrong.... as I received a kit with no schematic... so I used four different schematics I found online... so I made a mix of all. But I have a horrible noise on RX every time i connect the antenna. Not having this issue with the 49'er transceiver or my home made regen receiver. I still can't figure out what it is. I even ended up removing completely the low pass filter from the output and I'm using a proper one with toroid instead ( external one ).... the noise level it's lower.... but still horrible. 73
The pixie have almost no filter. So you get everything into the audio amp. I operate it with batteries because of very loud 50Hz noise if I connecting it to an power supply. I would say this behaviour is "expected". The 49er has one real mixer and should be a little bit more selective. 73
Thank you.. ohh yes I know the Pixie is a little more noisy than the rest.. but I get the same no matter if I use a battery pack or a power supply. I think I will rebuild it in my own version ))) 73 my friend.
@@dxexplorer Check out VA3ROM's website on pixie mods. very interesting - www.va3rom.com/docs/ATD033.pdf As for the input noise, may be AM broadcast interference... the pixie is a toy so don't be surprised when it doesn't perform well :-)
Thank you so much. Ohh yes I a fun toy to play with hahaha. But I just hate mine doesn't work well hahaha. I'll have a look in a little. 73
I think you will like this one as well... www.qsl.net/qrp/txr/micro80.htm A Pixie with an audio filter as well ))
And how long a distance do you communicate with it?
I have to say I never made a contact with it. My antenna is not so big. So I think it is a way to less power.
I just built my own Pixie and haven't made any contacts yet either.
But the reverse beacon stations have spotted my calls even 700km away.
I have made 300-500km contacts with another few hundred milliwatt transmitter on 80m band.
@@JuhaK71 I have the feeling that a lot of HAMs are not able anymore to listen to weak signals. They catch only the S9++++ signals. But this is only my feeling. Maybe wrong.
@@JuhaK71 Wow!!! Can I see the design?
@@msnepaliman
You can achieve the same results with any 80m QRP transmitter.
There are a lot of schematics available on internet.
I built mine with a rare battery tube DLL21, because I have 2 of them.
Nothing really special in my design.
Essential is a good, properly matched antenna, good conditions for the propagation, a counterstation at the suitable distance and not too much the background noise.
I use a 12 V battery and have no trouble with my 2N2222 final. N9EGT.