Attenuating tx output

Attenuating tx output

Post by Frank Dinge » Fri, 16 Aug 1996 04:00:00

Quote:>   I want to drive it with 1 watt but my rig does not produce that .
> To cut a long story short is it possible to attenuate the signal
> between the transceiver and amp down 1 watt .
> Any suggestions/comments will be gratefully received.
> Stephen G7UXL

=============
Stephen , You can easily construct a 5dB attenuator by means of 3pcs
2 Watt carbon composition - or metal film resistors in a small metal
container eg aluminium cylinder packing (35 mm film roll) or in a
home made box from double sided PCB material. Keep the component
leads of minimal length,just to solder them together.  In the PI
configuration the 2 resistors across signal input and signal output
are 200 Ohms ; the 3rd resistor between in- and output is 33 Ohms.
With this attennuator, 5 Watts is reduced to about 1.5 Watts which
(if the poweramp input/ouput transfer is linear over its range ) will
give you an output to the feeder of about 60 Watts.
The above attenuator is based on 50 Ohms input /output impedence.

Although a standard resistor is 220 Ohms ,you might be able to select
a low value from  a 10 percent accuracy batch. The value won't be all
that critical for this application.
If you can find some 2 Watts carbon-composition resistors of 180 Ohms
or about ,you could try to remove bit by bit with a grinding stone
,checking the resistance frequently as the resistor value increases.
Success !
Frank Dinger , Inver by Tain , Ross-shire IV20 1RX - Scotland UK