Bandpass filter needed for 434mhz - Electronic Circuits Projects Diagrams Free

Shax · 29th February 2008, 04:12 PM

Hi all,

does anyone have a schematic for a 434 mhz (70cms) bandpass filter?
It only needs to be able to pass 100mw or so, so no huge power requirements needed!!

**Nigel Goodwin** · 29th February 2008, 04:18 PM

TRy the VHF/UHF Manual from the RSGB, or the RSGB or ARRL Handbooks, you should have at least one of those if you're interested in radio.

Shax · 29th February 2008, 04:28 PM

Quote:

Originally Posted by Nigel Goodwin

TRy the VHF/UHF Manual from the RSGB, or the RSGB or ARRL Handbooks, you should have at least one of those if you're interested in radio.

The only filter designs I can find seem hell bent on allowing 400watts thru.. I only need 100mw MAX.. Lugging a filter designed to pass huge wattages is an absolute no no for tracking a downed rocket!

**Nigel Goodwin** · 29th February 2008, 04:58 PM

Same inductor values, same capacitor values, just lower power components.

Shax · 29th February 2008, 11:16 PM

Quote:

Originally Posted by Nigel Goodwin

Same inductor values, same capacitor values, just lower power components.

Maybe, but the schematics / articles I have show the inductors made from copper tube!

I'm after a quick fix, not a complete redesign..

Oh well, never mind, back to Google!!

on1aag · 1st March 2008, 01:11 AM

Hi Shax,

Google for helical filters.

http://www.neosid.de/DWL/Teil3/Seiten/3.11.pdf

http://www.toko.co.jp/products/en/fi...helical_e.html

on1aag.

Hero999 · 1st March 2008, 10:13 AM

Quote:

Originally Posted by Shax

Maybe, but the schematics / articles I have show the inductors made from copper tube!

I'm after a quick fix, not a complete redesign..

Oh well, never mind, back to Google!!

Just make the coils with the same dimensions from thin copper wire.

Alternatively, the schematic should list their inductance values and you can easilly calculate how many turns of normal copper wire to use. Google for coil winding formulae.

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29th February 2008, 04:12 PM	(permalink)
Shax	Bandpass filter needed for 434mhz Hi all, does anyone have a schematic for a 434 mhz (70cms) bandpass filter? It only needs to be able to pass 100mw or so, so no huge power requirements needed!! __________________ ==== Shax. ==== A bus station is where a bus stops... A train station is where a train stops... On my desk I have a work station... Nuff Sed!!!

29th February 2008, 04:18 PM	(permalink)
Nigel Goodwin	TRy the VHF/UHF Manual from the RSGB, or the RSGB or ARRL Handbooks, you should have at least one of those if you're interested in radio. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

29th February 2008, 04:58 PM	(permalink)
Nigel Goodwin	Same inductor values, same capacitor values, just lower power components. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

1st March 2008, 01:11 AM	(permalink)
on1aag	Hi Shax, Google for helical filters. http://www.neosid.de/DWL/Teil3/Seiten/3.11.pdf http://www.toko.co.jp/products/en/fi...helical_e.html on1aag.