Just noticed a product that could be very handy to maybe save that harmonic infested FM transmitter you purchased on line. It’s an FM Low Pass Filter that blocks unwanted harmonics:
Just noticed a product that could be very handy to maybe save that harmonic infested FM transmitter you purchased on line. It’s an FM Low Pass Filter that blocks unwanted harmonics:
http://www.ramseyelectronics.com/cgi-bin/commerce.exe?preadd=action&key=FMLP1
Also of interest is the place we learned about the FM filter:
http://lrn.fm/broadcast/station/
Wear your seat belt, signal before turns and watch the speed limit.
Long Time Item
That filter has been around since Ramsey opened it’s doors. Bought one way back in 96 along with my FM-100 kit.
It is a great filter and works best between exciter and IPA.
For output I recommend 7 pole or up.
RFB
Filter
A LPF can be effective in suppressing harmonics but be careful about assuming the filter will protect from interference. For example, a spur can appear near the operating frequency which could be in the adjacent aircraft band and get through the filter with little attenuation. This is possible with simple filters.
A high order filter as suggested by RFB is a good idea but also be aware that suppression of spurs depends on the out of band characteristics of the filter which change with different source and load impedances.
The point is that a filter may not provide the protection as expected.
Neil