[TenTec] Power attenuation for Ten-Tec 509

[Dr. Gerald N. Johnson]

On Tue, 2006-09-12 at 15:27 +0200, Mats Strandberg wrote:
> Hello!
> 
> I am the happy owner of a Ten-Tec 509 that according to the manual should be
> capable of delivering 3 Watts RF Output.
> 
> In the Swedish Portable Contest, there is a Power Multiplier that demands
> the RF output to be less than 1 Watt.
> 
> Can anyone supply me with information of suitable Power attenuators that
> could be used to reduce the 3 Watts down in several steps, for example
> 1,5W/1W/500mW/100mW?
> 
> Thanks in advance for any possible help.
> 
> SJ6R - Mats

There are tables of attenuator resistor values in many radio handbooks,
ARRL and some RSGB included and sometimes formulae for designing them.
Use 2 watt metal film resistors and they will handle all your power.

You need 3 dB to get from 3 to 1.5 watts, 5 dB to get from 3 to 1 watt,
3 dB more to get from 3 watts to 1/2 watt and ten dB to get from 1 w to
0.1 watt. All can be cascaded in any order so long as all are built with
2 watt resistors.

The closer you match the resistor values to the computed values, the
more accurate the attenuation will be, so looking for closer precision
than 20% tolerance resistors can help that precision. I worked up
computer programs once for picking attenuation values using standard
value resistors and trimming impedance with more than one resistor in
the center element of the T, but its in CP/M and hard to access these
days.
-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer