[CQ-Contest] A bandpass filter design

[Peter]

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 at 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
>>>
>>>