[time-nuts] locking oscillators - an increase in power and/or stability ?
shalimr9 at gmail.com
Sat Oct 11 15:25:14 UTC 2014
I have been doing phase combining of power amplifiers for almost 30 years, professionally.
If I could get 1200W by combining two 300W amplifiers, I would now be retired and very wealthy indeed.
Unfortunately, there is no free lunch and unless somehow the Gun oscillators were delivering more power when connected to the magic T (maybe because of better matching) than when measured individually, combining two X W sources will only give you, at best, 2xX W, or 3dB more power.
It does not matter what the combining structure is, magic T, coupler or else.
On October 8, 2014 5:22:23 PM CDT, Bob Camp <kb8tq at n1k.org> wrote:
>In the case of a magic Tee or a normal power splitter (both passive
>devices), the current will not be limited by the combiner or the
>source. With a proper combiner, the source will always be running into
>50 ohms. You will indeed get 6 db in the in phase sum case.
>On Oct 8, 2014, at 4:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd)
><drkirkby at kirkbymicrowave.co.uk> wrote:
>> On 8 Oct 2014 20:26, "Bob Camp" <kb8tq at n1k.org> wrote:
>>> It’s called injection locking. The two oscillators (or what ever)
>> at exactly the same frequency and some arbitrary phase. Depending on
>> amplitude and phase at the sum point, the result can be anything from
>> to zero power. Anything that oscillates can injection lock if given
>> right feedback at the right point.
>>> The gotcha is that they are at the same frequency, so they add as
>> voltages rather than power. In phase, equal amplitude, you get 6 db
>> power. Exactly 180 degrees out of phase and exactly equal power and
>> nothing (no power at all) at the sum point. Off by a fraction of a
>> or a fraction of a db and you still get roughly 6 db in the zero
>> But while voltages could double, that is not going to happen if
>> limits the current.
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