Thursday, February 18, 2010

10.7 Mhz FM IF TX - Mixed to 144Mhz


I decided I was not waiting for some 10.7Mhz IF cans to test the "rig", so placed a small "can" (KANK3335) in the colector of the second transistor and the "can" output to an SBL-1 mixer, then connected the Si570 vfo to the IF input on the mixer and the output to a small peace of wire near the TM-D700 antenna. Here we go! We have RF!!! Don't have a spectrum analyser but sure it should not be a beautiful sight in the RF output....

In the first "on air" test I was a little out of frequency, corrected that but the camera stop filming ("no space left on device" for those o know the meaning....), anyhow it neds a lot of filtering and a lot of improvement on the modulator side (stability). When I decide to finish this and give the project a box probably will not use the SBL-1 (will use original design) and will be putting the frequency rock bound since I almost ever use the local repeater or make qso's in VHF.
The microphone section needs to be corrected and properly adjusted. If I speak to close I have some distortion, if far away I listem to my own voice and can't make a correct judgement on quality. Probably will put some headphones and record several transmissions...on 10.7Mhz :) For sure there are some precise testing procedure for mudlation adjust, will investigate if there are any "tuna tin" or "Altoids" project on the subject.
The video, isn't it beautifull when something actuali work.... kind of...:

video

2 comments:

Anonymous said...

What's the meaning of IF?

Ricardo - CT2GQV said...

Intermediate Frequency.

http://en.wikipedia.org/wiki/Intermediate_frequency

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