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How low of a frequency will a typical SWR meter register? When I key the mic without talking into it when trying to transmit in SSB, should there be any deflection on the swr meter?
If a transceiver has am, usb and lsb modes of transmission, does it switch back and forth between being a direct conversion device (or no IF) for AM and a superhet for usb and lsb? The one I am specifically wondering about is a President HR-2600. I am having trouble determining the answer to...
I think the garbled transmissions are caused by noise from the power supply getting into the modulation amp. The supply measures about 30VRMS when nothing is hooked up. Is it better to use a linear supply? I think this one is a switcher.
George
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will an LM7812 circuit...
Hello,
Does anybody know what kind of antenna the pixie transceiver would use, and what impedance?
George
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actually, I figured out that at 80M the output Z is 50 ohms. So that answers my question. The one I built had an output Z of 50 ohms, but I had to go with a lower...
I noticed that when I tried to measure the audio in the lm386 circuit using a capacitor in series with the ac voltmeter on the 10VAC range, I would get a full scale deflection on both the input and output even with no signal applied. If I remember correctly I even got it on the power supply...
Hello,
As seen in video 10 in the website below, the transmited signal sounds unclear when received on the general purpose receiver. I can't tell if it is overmodulating or undermodulating. It has one stage of LM386 with gain = 200 for amplification prior to the mixer. The output is...
I tried your suggestion and it somehow killed the oscillator. It didn't destroy it, it just wouldn't osclilate when hooked up that way. I also tried putting a 2Kohm resister in place of the 10K as the output resister on the mic, but now I don't get any modulation. Could I have damaged the fet...
Above is the oscillator. It has a 10K resister applied to the input , through which the output of the LM386 is applied. It is a standard LM386 circuit with the 10uF cap between pins 1 and 4 and the filter on the output. The LM386 has a 50kohm input impedance. It is driven by the mic.
George...
Hello,
I biased an electret mic with 10Kohms and I don't get much modulation on the transmitter it is connected to. The load impedance is 50Kohms. Should I increase the bias resister on the drain of the mic's fet to a 50Kohm resister, or would that be ridiculously high? Would it be better...
Thanks Keith, I added a buffer earlier this week. If I have any more problems with th frequency I'll change the capacitor on the base (I presume you mean on the buffer input?). The buffer seemed to fix the frequency shift problem. I was just wondering why I had to use so much buffering, but I...
Hello,
The transceiver shown on this site: **broken link removed**
supposedly works OK. So I am wondering why I have been having so much difficulty with the audio circuit and with frequency pulling, with the one I am building of my own design, but which started out before modifications to be...
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