I offered to make a bandpass filter for one of our members. I have ordered enough material to make three of them. If anyone else is interested please let me know. These are very low loss (~ 0.25 dB) 50mm square by 180mm long (plus connectors) £50 including UK post.
Ken G3YKI
23 cm Bandpass Filter
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This forum is run by the BATC (British Amateur Television Club), it is service made freely available to all interested parties, please do not abuse this privilege.
Adverts will be archived when the seller indicates that the item is sold or after one year. If you wish to keep advertising after one year, please re-post.
Thank you
Re: 23 cm Bandpass Filter
I'll have one will message you. John G8IKP
Re: 23 cm Bandpass Filter
Hi,G3YKI wrote: ↑Wed Dec 11, 2024 11:43 amI offered to make a bandpass filter for one of our members. I have ordered enough material to make three of them. If anyone else is interested please let me know. These are very low loss (~ 0.25 dB) 50mm square by 180mm long (plus connectors) £50 including UK post.
Ken G3YKI
What is power handling please ?
Ken G8VDP
Re: 23 cm Bandpass Filter
To Ken G8VDP
Hi, Well it is difficult to be precise about these things! I have used one and it seemed fine with 100W mean power and 300W PEP.
Maybe that is plenty for you, or do you want to push it a bit further? It is normally proposed that you do not need to use a bandpass filter at the output of a transmitter, just a harmonic filter. Any noise or spurious from the driver stages should be filtered before the final PA. However, a very low loss is useful to go before the input of a receiver when TV/Vodafone etc. present a problem.
Regards, Ken
Hi, Well it is difficult to be precise about these things! I have used one and it seemed fine with 100W mean power and 300W PEP.
Maybe that is plenty for you, or do you want to push it a bit further? It is normally proposed that you do not need to use a bandpass filter at the output of a transmitter, just a harmonic filter. Any noise or spurious from the driver stages should be filtered before the final PA. However, a very low loss is useful to go before the input of a receiver when TV/Vodafone etc. present a problem.
Regards, Ken
Re: 23 cm Bandpass Filter
Hi Ken.
Thanks for replying quickly. Yes I completely agree with what you've said.
I was curious though.
These things being available from several sources & often used in repeaters. Of course there's going to be comparisons.
At your price & suggested specifications+ power handling they're a total bargain.
Best regards Ken
Thanks for replying quickly. Yes I completely agree with what you've said.
I was curious though.
These things being available from several sources & often used in repeaters. Of course there's going to be comparisons.
At your price & suggested specifications+ power handling they're a total bargain.
Best regards Ken
Re: 23 cm Bandpass Filter
Depending on the design, bandpass filters are not necessarily good for suppressing harmonics. There shouldn't really be a need to put significant RF power through them. If they get hot, they may detune. For higher power applications, e.g. over 100w, it is probably better to have the bandpass filter in the RX chain and a harmonic filter in the TX chain.
Incidentally, the DCI bandpass filters for 2m are rated for 300W. Rather less than you might expect from their size.
Mike
Incidentally, the DCI bandpass filters for 2m are rated for 300W. Rather less than you might expect from their size.
Mike