On Low power -48 dbm I was using my Sainsonic AX-05B only to transmit my Teamspeak conversation with Station 8 to the Radio as a better speaker than my Laptop. Just as the last meeting the Radio tripped and the audio was muted. I had to wait a few minutes for the Radio to reset and plug headphones into it and unplug the headphones. The speaker finally came on. Then I listened for several minutes to another station and all was well. OK so I fired back up my Transmitter and tuned down the modulation just to be sue it was not because of that. I was able to listen to the Radio until Station 8 keyed up the mic and CLICK the protection circuit was tripped again. Also as you tune from 1.7 Mhz all the way to 12 Mhz I could hear this transmitter transmitting harmonics all the way down the shortwave dial WHAT A NIGHTMARE!! This didn't happen as soon as I got the transmitter but as time went on the harmonics got worse on all Radio's in the house. You can best bet Monday I'll be calling SainSonic and demanding my money BACK. How many Radio's in my neighborhood did I destroy with this transmitter? Thank God I accidentally had this on Low Power all week and my signal unknowingly was not leaving my house as I was going to turn to Low Power and found I was already there. God was looking out for me so Thank you Jesus for doing that.
It seems as though after prolonged use of even the revised SainSonic AX-05B (4 months and 5 days) is when their cheap filters burn out. So it will behave until the filter fries and your left causing all sorts of pollution all over the spectrum. Though this transmitter looks and sounds great when you buy it, it does not stand any real world use. NOTE: I never dropped this transmitter or over modulated it. In fact I babied it and did not let friends borrow it. I would never run it while I was not close by in case it ever miss behaved like Today's circus escapade it pulled on me earlier. If I can't get it fixed or replaced I hate to say it but its going to be sent to a good friend who knows Electronics and rebuilt from the ground up and with 7 pole band pass filters all over it. When done there is NO WAY it will have a chance to miss behave ever again. I'm going back to 1630 AM and my almost $300 Talking House 5.0 Transmitter tested and certified to behave. You have all been warned. Pass this message to anyone you know. Even Your Facebook wall too because something needs to be done about SainSonic's miss practice in making a Transmitter they are unsafe for the environment and a threat to your wallet. Thanks for reading and I hope this is not considered an Agenda thread.
(No, this is not an agenda thread.)
It is possible that what you observed as spurs and harmonics and the receiver "protection circuit trip" was caused by it being overloaded by being too close to the transmitter. Though the field strength produced by Part15 FM transmitters is puny, it is very strong near the transmitter.
Maybe before expending all the effort on the transmitter you can try moving the receiver away from the transmitter and/or checking the signal with another receiver also not too close to the transmitter.
Years ago I built a one transistor FM transmitter and had a lot of trouble tuning it. I would set the receiver on an empty frequency and would hear several signals as I rotated the tx. tuning cap. I also heard many "images" up and down the FM band until I moved the transmitter across the room and then only heard one signal. This is what makes me think it could be that your signal is too strong for the receiver and maybe it is not dirty.
Neil
Also check the power supply!
When I temporarily couldn't find my Talking House's heavy transformer supply, I used a lightweight switcher supply, and on the Panasonic radio across the table, there were humming hash carriers all across the AM tuner! The radio was powered from the same strip as the TH. It was switching noise by carrier current probably.
Yes, even small FM transmitters can overload, the symptom for me was my signal being heard several places on the the band, like between stations and mixing with local full powered signals.
I had a scare from that, but here's what to do for AM and FM, take a radio outside and see if the problem goes away, or try a car radio outside, if it's clear, it's gonna be clear for everyone else too.
I notice when I go outside that the images of the fundamental frequency does clear up. But I still can hear BUZZ BUZZ and a faint image of my station. This is at the 500 mW setting. At the -48 dbm setting I can get things to work OD further but I have to use compression. Any slight spike of a non compressed signal and all hell breaks lose and the Radio is tripped again. My Boom Box also seems to flake out with this transmitter as well. It seems like something is spewing into the IF frequency too as when I tune up and down I'll hear what sounds like a buzz changing pitch and when the TX is off that is gone. The car Radio picks it up just outside of the house a few feet and does fade as you go down the road at 500 mW to about 150 feet but seems to still be mixing but at weaker stations. So its spewing something. Radio Brandy posted a warning about the CZE-15A a transmitter that went 0-15 Watts. I'm wondering if it is in that BH 1415 chip from Japan. I've tried different power supplies too except the TH one as that was 18 volts and the TX has a 12 volt power supply. Like I said it scares me now because I live so close to police and fire and I have fire and rescue trucks drive right by my house (in the harmonics path) and I'm afraid it could do something to a heart monitor or their Radio's. The house next door is RIGHT IN the harmonics and spurs zone too. If you knew where I lived you may be scared too as my old TX in Michigan that went 3 miles did not do this and yet I went 3 miles with it. I feel I'd deserve a NOUO if I keep at using this transmitter so I'm doing what a good broadcaster should do when a problem is discovered. I'll write Radio Brandy too and see what he says about this transmitter, but I bet he is gonna tell me to chunk it or rebuild it somehow.
Any tests I do now with it are very short. I can't risk people's lives for my hobby. I'll save for something better first. Unless someone knows how to build a filter for it. Still may be cheaper to buy one of Tim's unwanted transmitters when he is done with it. At least I know what the harmonics look like if he throws it on a spectrum analyzer.
This does sound like something other than overload is happening and you are being very responsible in dealing with it.
Neil