On 8/3/20 11:13 AM, David Gilbert wrote:
Hi, Jim.
Do you plan to use this for transmit, or for receive?
I'm no network expert, but if you intend to do this for transmit I don't
think you can variably shift the phase AND also at the same time have a
good match by this method. Maybe you plan to switch the tuner in for
receive and out for transmit, or switch between two tuners.
Multiple tuners.. two cascaded allows you to shift phase and transform
the impedance so that when they are in parallel it's 50 ohms. So 4
tuners all together make a 50 ohm load.
I think that one might be able to get by with 3 - and you let the
"joining point" assume arbitrary impedances. And the typical computer
tuner has a single L and a single C, so there's not much point in
switching multiple "C"s to the joining point.
Not a whole lot different than used in the broadcast business.
For what it's worth, on receive, you might as well do it in software.
Some years ago, I was going to try this with software on Tx, and
separate 100 W PAs, but those PAs are still sitting as kits in the garage.
And if you intend to do this only for receive, you could accomplish the
same thing via software at audio IF you use a rig with two synchronized
receivers, such as the Elecraft K3/K3s in diversity mode.
On the second point, I have a few times lobbied Elecraft to add that
capability to their firmware but they don't seem to recognize the
potential of it.
73,
Dave AB7E
On 8/3/2020 10:56 AM, jimlux wrote:
On 8/3/20 10:20 AM, sawyered@earthlink.net wrote:
Why is it that direct control of L and C are required? I use the MFJ
high
power tuner and have no issue with it on auto tune finding a good
match for
my 80M phased dipole array.
I want to use it to change the relative phase of the antennas to move
the nulls.
It's more a "phase shifter" than a "matching network"
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