|
Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
|
Thread Tools |
8th Jul 2019, 2:46 pm | #21 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,013
|
Re: 4 port Wilkinson combiner / splitter question
Here is the MW/LW hybrid coupler. Found deep in the shed.
Board has a corner that got cracked at some time. |
9th Jul 2019, 1:39 pm | #22 |
Heptode
Join Date: Nov 2011
Location: Whitchurch, Shropshire, UK.
Posts: 612
|
Re: 4 port Wilkinson combiner / splitter question
Oooh, big pots! I'll show you mine later just doing the cabling tonight. Thanks Jon, is it for sale....?
__________________
Best Regards, CW. 2E0ILY |
9th Jul 2019, 4:46 pm | #23 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,013
|
Re: 4 port Wilkinson combiner / splitter question
Haha sorry Chris it's a bit of history to me so not for sale.
Happy to discuss the making of something similar though. It works just like the 600 Ohm ones for POTs using 3 windings on each transformer. |
9th Jul 2019, 11:21 pm | #24 | |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
|
Re: 4 port Wilkinson combiner / splitter question
Quote:
However, there is another approach. If it is reflected with the right phase delay it winds up back at the merrily switching PA device and gets re-chopped. Some of the harmonic energy gets converted to the wanted output frequency and with care this can be made to be of a helpful phase and combines with the wanted output. The other products keep getting reflected back and re-chopped until they eventually make it out as wanted output. The overall efficiency climbs. I have a 120MHz PA running comfortably over 80% efficiency, including matching losses, filter losses, and detectors on a directional coupler. Perfect class C has a theoretical max limit of 66.6666% Once you can play this game over a moderate bandwidth, you qualify as a mage of the 8th order and get a free pointy hat with 'Wizzard' written on it, (in crayon). David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
|
11th Jul 2019, 10:27 am | #25 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,013
|
Re: 4 port Wilkinson combiner / splitter question
That could be a good wheeze for a band as narrow as the 136kHz allocation.
Then the combiner could be quite narrow band too. I have also made quadrature hybrids from bifilar wound ferrite inductors with capacitors across the ends of the windings. Never for a frequency as low as 136kHz but why wouldn't it work? It's fine at 50 and 70MHz. That range was never available from a certain company. I therefore called this the winger coupler. Last edited by Jon_G4MDC; 11th Jul 2019 at 10:48 am. |
13th Jul 2019, 11:01 am | #26 |
Heptode
Join Date: Nov 2011
Location: Whitchurch, Shropshire, UK.
Posts: 612
|
Re: 4 port Wilkinson combiner / splitter question
Thanks Jon and i quite understand! I may have a go at a transformer combiner next, just for the experience.
__________________
Best Regards, CW. 2E0ILY |
13th Jul 2019, 11:03 am | #27 | ||
Heptode
Join Date: Nov 2011
Location: Whitchurch, Shropshire, UK.
Posts: 612
|
Re: 4 port Wilkinson combiner / splitter question
Quote:
__________________
Best Regards, CW. 2E0ILY Last edited by Chris Wilson; 13th Jul 2019 at 11:09 am. |
||
13th Jul 2019, 11:21 am | #28 |
Octode
Join Date: Dec 2008
Location: Wincanton, Somerset, UK.
Posts: 1,757
|
Re: 4 port Wilkinson combiner / splitter question
Chris: The LPF circuit which you posted at the start of this thread can be adapted to form the leg(s) of the Wilkinson combiner.
The C-L-C topology used in the lumped combiner circuits is a narrow-band approximation to a quarter-wave line: by increasing the number of elements in this lumped circuit you get closer to modelling the behaviour of a true transmission line. I guess it's a practical matter of whether you're happy to wind a few coils to make this combined 3-way hybrid / LPF? John |