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This is what I do: Connect the Vector Network Analyzer between your wire and a counterpoise and sweep the frequency of interest, looking for X to be 0 (neither negative or positive). If the value of X

Pick a suitable range for the A-600, e.g. about 13~15 MHz for 20m and scan that range. You should see a dip in the graph pattern. Adjust the tuner for deepest dip (lowest SWR) which will be at the

I borrowed an analyzer, a RigExpert AA-600. hive-mind help needed. how do you find the resonant length of a single wire, using a fancy gizmo? what I've tried so far is putting the wire in one side of

you might be mistaking my antenna for a different one. this little tuner is connected to my radio via an 8" pigtail.

All: Conditions were not ideal, but we did get some RBN reports. While it's far too soon to say much, it appears the mag loop gives up about 1-2dB over the EFHW, which is up about 60' or so. VE8JY in

All: Today we began testing Al's new mag loop (ML) design, shown here: It's a 40-30-20M "luggable" loop. It's about 3' in diameter, breaks down so it fits in a car, and we can get almost 1.1:1.0 on

Hi Lloyd, Generally, you start adjusting the highest band and work down through the other bands but as, you discovered, with a multiband trap antenna there are interactions among the bands so tuning

I'm wondering if someone can suggest a method, not involving using an antenna analyzer, to gradually construct this antenna so that it matches on all three bands? I began by putting it together with

Yes but KK7B uses opamp biased to a 6V rail using 12V. So yes at the CB end its not a big deal, at the other end of the 3 stage all pass headroom is a good thing. Allison

Because it's fun to do, and may as well complete project before cleaning up, plotted dynamic range. https://www.kn5l.net/commonB/ 2N3904 gain plot added. 1dB gain compression is -21dBm input. Measured

Hi Allison, I was commenting about battery voltage range rather then current. Modern three cell LiPos sag down into 11V range. Some additional measurements at both 8 and 12 volt supplies.

Hi John, I can see field friendly easily. The MicroR2 does about 55ma for the whole receiver on 40M. That is without CMOS opamps (uses 5532). Allison

Found some new ON Semi 2N3904 ordered a few months ago. New schematic in: https://www.kn5l.net/commonB/ Using common part values. Very close to Zin = 50 Ohm. Moved output to mid Vcc, which increased

Look at KK7B R2/miniR2/MicroR2 as his solution for power was a capacitance multiplier at 12V. Higher voltage allows greater dynamic range. Looks like I wrote the wrong current down, though it should

Some additional comments: Added KK7B form emitter follower, no change in input Z. Input Z is a function of Vcc. Changing Vcc to 5V requires Emitter current ~= 0.7 ma for 50 Ohm input Z. Emitter load R

Hi Allison, Common Base Amp breadboard and measurements: https://www.kn5l.net/commonB/ Emitter resistor adjusted for 50 Ohm input Z. Can't get much closer to 0.5ma. KK7B form used 2.7k emitter

ajparent1/kb1gmx writes: The OP was primarily addressing audio, such as a DBM being used for a direct conversion receiver (or maybe the product detector in a superhet). Though, I have little

Paul, For the case where the desired signal is audio and the DBM source is a Common base amp is the desired case. For a mixer to RF then other possible choice may have favor. The KK7B form is Common

John, Yes, that work if the output desired was the RF signal (SUM). For audio the 100uh choke would have to be something like 10 Henry. Allison

John KN5L writes: I have used common emitter amps similar to the above with feedback and a stiff partially bypassed emitter with good success. Another option I prefer is to use a common base (CB)