In a general RF power combiner the difference of amplitudes or phases
between the 2 sources to be combined has the following effects.
1.) Equal TX amplifier amplitudes and phases = max. power output
2.) One TX amplitude reduced 1dB (20.5%) but no phase difference yields
power output -.45dB below max.
3.) TX amplitudes max but phase difference of 30 degrees yields power
output -.30dB below max.
The effects on the total output are surprisingly not that affected by
small gain and phase errors.
Larry, W0QE
On 8/23/2012 6:30 AM, peter chadwick wrote:
> How do you ensure phase matching between the amplifiers?
>
>
>
>
>
> ========================================
> Message Received: Aug 23 2012, 01:16 PM
> From: "Sam Carpenter"
> To: amps@contesting.com
> Cc:
> Subject: [Amps] Multi-Amp w/ Power Combiners
>
> I have often thought of why I do not see the running of multiple HF Tube
> amps with power combining networks. It would seem that the overall cost of
> using more than one smaller amplifier would be a net savings because of the
> relatively low cost of building medium power amps. It seems like a
> reasonable way to build a lot of power and spread the stress of a system out
> a bit to lower priced components. It also partially eliminates the single
> point of failure to take all the power down with a single glitch. I
> understand that frequency agility would be more cumbersome and time
> consuming, but in many applications, you don't move much. Neither input nor
> output combining is complicated so long as you are staying fairly put with
> regard to frequency. Does anybody do this outside of broadcasting and
> commercial? N9FUT
>
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