dinsdag 22 september 2009

some results

Last night I reduced the power of the LO amplifier to 5 mw.
Then I mounted the mixer (HPF-505). Now I have a basic transverter.
No band filters were build yet.

I was curious if stations could be received using this setup.After all 40 meter contains a lot of broadcast stations. So I hooked up the cb set to the IF port of the mixer. My antenna was just 50 cm of wire.

I did receive a lot of broadcast stations. I was even able to hear a lot of ammateur stations. That is a nice result. Connecting the antenna increased the noise to S5 level. So a preamp may not be necessary. I'll check again when the bandfilters are ready.

Then I tried to transmit. Success, the LSB signal sounded good on my FT-950.
Of course the output signal is small, a few 100 mv at the non terminated IF output.

During reception I found out that The CB sets produces too much high tones. I already expected this. So I'll have to add a LC lowpass filter with a cutoff frequency of 2200 Hz. I will put it between the amplifier and the speaker. That is not the best solution. However it requires only a small modification of the CB radio.

I started building the band filter and the attenuators. I hope I can finish it today. Soon I will upload some pictures and a schematic diagram.

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