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| To: | "J. Allen" <[email protected]> |
|---|---|
| Subject: | RE: LF: Antenna or transmitter tuning |
| From: | "Laurence KL1X" <[email protected]> |
| Date: | Mon, 31 Jul 2006 00:05:36 -0800 |
| Delivered-to: | [email protected] |
| Reply-to: | [email protected] |
| Sender: | [email protected] |
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Just statiing one of things I found was the I had probs with high local fields from my own transmiiter aerial affecting the oscilloscope readings. I had a load of v/m as my loop running N amps was only meters from the shack - nothing was wrong per say but I had to take care with the screen test leads and add an RF filter on the AC power lead - all became clear. Ao as I ramped up the power, save for a small change in the waveform everything looked fine -without the filters it looked worse and worse. Prob not your prob though. Laurence in rainy Singapore > From: [email protected] > To: [email protected] > Date: Mon, 31 Jul 2006 06:57:27 +0000 > Subject: LF: Antenna or transmitter tuning > > Hello again Friends, > > The single FET amp which Steve lent me has been working fine, but if you > remember, during tuning the antenna system would come up with some weird > wave shapes. The amp uses an air core output coil. The antenna loading > coil , its matching coil and both coils in the transmitter's Low Pass Filter > are air core as well. So there is no iron in the working system. > > Remember that when the antenna was tuned, one suggestion was to place a > matching transformer with TV Horizontal Ferrite core in the circuit. When > that was done, the waveform on the scope turned to garbage. (high in odd > order harmonics) > > Today, the two FET amp which Scott lent me was put on the air. It has a > ferrite TV output core which I wound and even though it was placed at the > exact length of coax from the antenna which Steve's amp had been, it 's > output waveform is badly distorted. > > It is important that I run the station at the maximum allowed IERP for the > sake of proving non-interference. > > On Scott's amp, the current and voltage waveforms are identical and in > phase, the amp runs very stable at over 300 Watts input, but the waveforms > look awful. I have decided to switch back to Steve's transmitter and > revisit both the output of Scott's amp and the antenna system. I am > considering winding a air core transformer for it, but am unconvinced doing > so will solve the real problem. > > I have a scopematch, and scope, an rf source capable of 18 kHz and up. > > Any ideas on how to approach this waveform problem? > > J. > > > With MSN Spaces email straight to your blog. Upload jokes, photos and more. It's free! It's free! |
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