Is It For Real???

[ridgescan]

I found my old Radio Shack amplified shortwave antenna so I thought I'd try it on the R71. I connected it to the discone and to the R71 with shielded RCA patchcords (of course I cut one end on each patchcord to hook into the R71 and to the antenna switch)
I tried fishing around on google to learn how this thing actually works-I think since it has its own SW tuner, a variable RF gain and 9 volts it has to be actually amplifying incoming signals because it also amplifies noise too. Can this thing actually give that dramatic an improvement with just 9 volts? Anyways it's a lot of fun to see even stronger signals

 

[SCPD]

Ridge, it's not magic.

The active antenna is just matching the impedance from source to your input. Most also provide some kind of amplifier circuitry as well - some times more than one. Your meter was just responding to an increase of signal voltage.

e.g. MFJ Enterprises Inc.

The MFJ-956 is a simple matching device (but lacks the amplifier.)

Matching can be done in several ways: Physically (by making an antenna tuned to the exact operating frequency) or Electrically (the active antenna method.)

Some reading topics:

Active Antenna

http://www.ramseyelectronics.com/downloads/manuals/AA7.pdf

 

[ridgescan]

Thanks Nick This thing is very effective-so that little "tuner" is the antenna matcher and the RF gain is the signal amp. Appreciate your help. Good thing I hung on to this little gem

 

[DickH]

...
Can this thing actually give that dramatic an improvement with just 9 volts? ...

Try it with 12 volts (and have a fire extinguisher at hand).

 

[ridgescan]

Try it with 12 volts (and have a fire extinguisher at hand).

LOL! hey I want to keep it for a while actually I have an old "Recor" multi-voltage power supply hook to it-the antenna thing works even better on lower voltages like 3.5 and 4.5. It still brings in the signal better without so much noise and I can use the RF variable more

 

[DickH]

LOL! hey I want to keep it for a while actually I have an old "Recor" multi-voltage power supply hook to it-the antenna thing works even better on lower voltages like 3.5 and 4.5. It still brings in the signal better without so much noise and I can use the RF variable more

Good thinking! Sometimes it pays to fool around and experiment.