I am expecting my new transmitter in a couple of days and have a question about low pass filtering. My new TX has a LPF cutoff of 108 Mhz and the one I built (see old thread)has a cutoff of 150Mhz. Most of the stuff I saw online said run both, so does it matter witch one is first in line??
See which way your SWR meter is happiest, but it shouldn't matter.
Well I hooked up my new transmitter this morning (AAREFF 100 Watt) it has a built in FWD/REF meter, so the answer is with my home built LPF the swr was 2:1 and just using the LPF on board the TX my swr is 1.3:1 so I am thinking there is something wrong my home made LPF or the connections . So for the time being I will not be running both . sixer
I have no idea what you just said (way over my head). My new TX is Industry Canada approved so I think the on board LPF will do just fine. I will keep the one I made and use it with my old transmitter(czh 7c). After 12 hours of burn in and a little adjustment my SWR is now 1.2:1. I like the numbers. Tomorrow I will be out driving around to map my new coverage. SIXER
Sounds like the home brew filter is not on the right track so to speak. It might be too far back into the band at the cut off than outside of the band...ie notching part of the FM band instead of what's above it, where the filtering needs to be.
Peace
K-ROCKS RadioOne
ZeroPointRadio
AM Stereo 1670
FM Stereo 92.1
Sounds like the home brew filter is not on the right track so to speak. It might be too far back into the band at the cut off than outside of the band...ie notching part of the FM band instead of what's above it, where the filtering needs to be.
Without checking with a RF sweep gen, detector and scope (or more exotic - spectrum analyser), a definate possibility.
I have no idea what you just said (way over my head). My new TX is Industry Canada approved so I think the on board LPF will do just fine.
Yeah, 2H and higher will be 60dB down, most likely.