[CQ-Contest] A bandpass filter design

[Jukka Klemola]

OK Peter,
The discrete component based solution is better as you have acquired the
necessary skills.
Taking into account your space limitations, your solution is excellent.

At OH0V, we built a separate room for double stubs.
Everything is 7/8 hardline.
One set of pictures here:
https://www.youtube.com/watch?v=1sQqTmxi0Js

At our summer house, we built filtering completely outside.
Everything is 1/2" hardline.

I have built also an additional coil-capacitor solution to attenuate 40
harmonic on 20.
I use it if we have a multiop effort at our summer house.
http://www.netikka.net/oh6gaw/galleria/


As you have done at PI4CC, the main building blocks of the station stay and
you can improve gradually through proper planning and engineering.

Keep on improving !


73,
Jukka OH6LI




2017-04-29 16:12 GMT+03:00 Peter <pc2a at pi4cc.nl>:

> 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
>>>>
>>>>
>>>>
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