[amsat-bb] Improved Bias Tee

["w4tas" <w4tas@xxxxxxx>]

I have constructed a bias tee to be used with 
such converters as the Drake, TSI, DEMI and 
others that are fed through the coaxial cable.
It contains a fuse, current limiting resistor 
and back to back signal diodes to prevent 
excessive RF from entering the converter and 
causing it to fail. 

If anyone is interested in the schematic and 
a short description, please send a personal 
E-Mail to me and I will return the information. 

The information is contained in a 130 KB JPEG
image. The information is sufficient to construct your 
very own bullet proof bias tee. If you need further 
information I will be glad to help.

>I haven't tried the unit yet because I don't 
>want to risk damage to my converter. 
>
>I have used the "back to back" diode arrangement 
>to prevent damage to mast mounted GaAsFet's in
>the past. I put the diodes back to back across the 
>output of the preamp to prevent damage from RF 
>leakage coming from coaxial cables in the same
>bundle. I learned about it by spending about $60.00 on 
>GaAsFet's in the early 80's while working AO10 
>and AO13. I was using a high power (500 W) 
>terrestrial station with a feed line in the same 
>bundle going to the AO10/AO13 downlink on 2 
>meters. 
>
>Good luck to all and keep those converters safe!!!
>
>73
>
>Tony
>W4TAS
>
> 
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