[CQ-Contest] A bandpass filter design

[Jim Brown]

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).

http://k9yc.com/LocatingStubs.pdf

I'm using stubs like these on the amplifier output in addition to 
5B4AGN's excellent TXBPF filter sets. See slides 16-20 in 
http://k9yc.com/7QP.pdf for a practical installation.


Suitable stubs can be built, tuned, and installed for far less than the 
cost of a high power bandpass filter -- it's the cost of the coax, 
connectors, and adapters (Tees and barrels), and any decent RG8 or RG213 
can handle far more than the 1.5kW output that's legal in much of the 
world.

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!
>
> We don't claim really high power, but its calculated for 1kW key down 
> and we tested them 15 min key down with the output of a Acom1000 
> without any issue.
> During a 24 hour contest in SSB and CW its works great and weak 
> signals near a second harmonic (2Kc) could be easy copied.
> It has better numbers as 4O3A, DG0SA, VA6AM.
>
> Have a look at https://www.pi4cc.nl/tech-info/hp-filter/ for more info 
> and details.
>
> We are is the stage of make an order for the pcb's, but its difficult 
> to get the correct amount.
>
> Peter
> PC2A
>
> Reference :
> 4O3A http://www.4o3a.com/index.php/products/high-power-filters/series-xl/
> DG0SA Funk march 2017 page 244
> VA6AM https://va6am.com/
>
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