10577Re: [loopantennas] Re: Varicaps vs old fashioned variable capacitors
- Apr 30, 2014
>I'll look at that later when I have a WiFi connection. The loop antenna is best viewd as being a current source with a series inductance and a low series resistance. When seen that way, series tuning with a low input impedance amplifier becomes obvious.
>Yes, that's the circuit. http://www.lowfer.us/k0lr/bal-pre/bal-pre.htm
>http://www.lowfer.us/k0lr/bal-pre/bal-pre.htm. I thought the point was to
>have such a high impedance that the loop/inductor was not effected by the
>directly attached preamp. Another interesting design is from the late
>Ralph Burhans. I bought and used his preamp way back in the 80's and lost
>it. I was happy to find the design again. However, it is not a tuned design
>and I'm not quite sure if I can just slap a tank circuit on the transformer
I think I placed a 1- or 2-page PDF files in the group files section that showed schematics for simple active antenna amplifiers using the CA3046 transistor array. If not, I'll look around the see where I put it. It's not on my office computer, so it must be on the laptop.
N7ZWY / WDX3HLB
Senior Member IEEE
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