Hi Jukka
The double stub sound OK
But its hard to manage when you just have 4 m2 of wall to mount all
filters/switching gear and multi antennas per band.
The bandpass filter will not only bring down the second harmonic, but
all harmonics with good figures And they clean up the receiver overload
from other bands.
With a single stub and build with RG213 we just get an notch op about
25db. This is the purple line
https://www.pi4cc.nl/tech-info/hp-filter/images/BPF%20Cauer+Cheby%2080m.jpg
We are not afraid for drifting since we use ATC800C capacitors and the
coils are mounted on the pcb. There is no mechanical pressure from the
connector to the pcb. Its attached via a wire.
Peter
Op 28-4-2017 om 21:37 schreef Jukka Klemola:
PI4CC have a very good single stub system.
https://www.pi4cc.nl/tech-info/stubs/
PI4CC have most likely believed the people claiming the double stub would
be just 6dB better than a double stub.
PI4CC result is somewhat better than any 2 stub arrangement would be.
I have an uneasy gut feeling about the presented filters, how they might
drift over time.
At least connecting&disconnecting the cables may present changes to coils.
73,
Jukka OH6LI
2017-04-28 21:45 GMT+03:00 Jim Brown <k9yc@audiosystemsgroup.com>:
Thanks Peter.
Bear in mind that bandpass filters between transceiver and power amplifier
will protect the receiver, and double stubs, optimally located along the
transmission line, can provide more than 70 dB suppression of the
amplifier's second harmonic (in addition to the 30-40 dB provided by the
amplifier's output network).
73, Jim K9YC
On Fri,4/28/2017 10:34 AM, Peter wrote:
Hi fellow hams/contest OP's
I just want to let you know that PI4CC is ready to bring there high power
bandpass filters pcb's available for the ham community.
This is hobby project and you can build a good bandpass filter your self!
Have a look at https://www.pi4cc.nl/tech-info/hp-filter/ for more info
and details.
Peter
PC2A
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