[BC] Xmitters at aol.com

[K7qa@aol.com]

In a message dated 4/6/2007 6:39:56 AM Pacific Daylight Time, 
RichardBJohnson at comcast.net writes:

> For a mile-long line, you will certainly
> have it equalized well enough for AM, perhaps even FM. In a previous life I 
> was able to equalize stereo pairs to 15 kHz, although I needed a Langevin  
> EQ-257-A  equalizer. It had a multi-turn wirewound potentiometer in series with
> the inductor.
> 

You really dont need an expensive equalizer unit to make up for the high end 
loss on such a circuit using the 111-C repeat coil. You can produce a reverse 
mirror image of the rolloff curve by using a simple resonant circuit with an 
adjustable insertion potentiometer. Use a 2.5 mH RF choke in series with a 5 K 
pot. Then place a 0.1 mfd cap across that to start and tack the entire network 
across the 111-C secondary winding at the receive transmitter site end. Send 
alternate 1000 Hz and 10 kHz tones from the studio end and adjust the pot as 
necessary to make the receive levels the same. If you need response flat to 15 
kHz or to flatten the response to within 1 db, you may have to reduce the size 
of the cap, or the RF choke down to 1 or 1.5 mH.

tm


**************************************
 See what's free at 
http://www.aol.com.