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Kuhne 3.4ghz pipe cap filters
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Neil Smith G4DBN
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geoffrey pike
Hi Ken, Never seen that back to back before must try it on 3cms , those figures IL are very good, always had poor results on 3cms though Cheers Geoff GI0GDP
On Monday, 30 January 2023, 22:12:49 GMT, Ken G3YKI <kenneth@...> wrote:
Hi Gareth "Could I ask what diameter pipe-caps you are using on 3.4?GHz?" 22mm work well at 3.4GHz. here is one I made earlier.  Inner 6mm brass screw or 1/4" copper tube. Probes are 8mm from the axis of the resonator. BW about 40 MHz at 3dB. 
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Gerhard_DK4XP
Am 30.01.23 um 23:12 schrieb Ken G3YKI:
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That's a nice one! I did some prelimininary experiments, but only with standard M3 screws. < www.hoffmann-hochfrequenz.de/downloads/PipeCapFilters.pdf> Cheers, Gerhard Hi Gareth |
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Hi Gareth
"Could I ask what diameter pipe-caps you are using on 3.4?GHz?" 22mm work well at 3.4GHz. here is one I made earlier.  Inner 6mm brass screw or 1/4" copper tube. Probes are 8mm from the axis of the resonator. BW about 40 MHz at 3dB. 
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Input / output coupling dictates filter bandwidth. It provides the transformation from Zo to the filter loaded working impedance, hence loaded Q. The probes then affect the coupling that, once the bandwidth is defined, sets the ripple . Qo/Qn and K1 ... kn-1 are teh normalised filter coefficients you look up in a table, where Q is the IP/OP transformation and K the normalised coupling I used to love filters - they're so mathematically precise Andy Handy info on probe length, IIRC it affects bandwidth and insertion losses so worth getting right for the band in question. Could I ask what diameter pipe-caps you are using on 3.4?GHz? |
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Gareth G4XAT
Handy info on probe length, IIRC it affects bandwidth and insertion losses so worth getting right for the band in question. Could I ask what diameter pipe-caps you are using on 3.4?GHz?
Thanks Gareth |
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Chris G0WUS
Many thanks that will save some trial and error
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73 Chris G0WUS On 28/01/2023 17:42, Stanislaw Ziemczonek wrote:
Chris, |
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Stanislaw Ziemczonek
Chris,
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3.4 GHz 7 mm above PCB 2.3 GHz 9 mm above PCB . 73's de Staszek SP6GWB Hi all, |
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Chris G0WUS
Hi all,
I have found 3 kuhne pipe cap filters for 3.4ghz can not remember where I got them. Can anyone provide the recommended probe length for them please? 73 Chris G0WUS |
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