They talk good on am and fm. 
I hope a channel board is available soon.
I hope a channel board is available soon.
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New Cobra 29 Am/Fm
- Thread starter Shadetree Mechanic
- Start date
i wonder if they have an fm deviation adjustment pot?
I think cobra hit a home run with the am/fm 29. The encoder feels as good as any other and I am glad to see mostly through hole and a transistor final.( I made the mess with the thermal compound.)
Another cheaply made cobra with a channel encoder the size of a small potentiometer that will last about a year. Add a push to it and maybe they will now last 6 months.
That is because they are overdriving it. FM is not like AM and it does not like to be driven hard. This is why FM won't play well on 11 meters in the US. Too many are used to getting the "swing" which FM simply does not do.
Us cbers are clearly not smart enough to run an fm station. If you have your carrier set for 2 watts to drive your amp on am It is not going to overdrive your amp with 2 watts on fm. Amplifiers will actualy take more fm carrier than am without distortion becuse you do not need the headroom for amplitude modulation because the amplitude of the signal is constant.
-Dumb cber at a truck stop hack shop
-Dumb cber at a truck stop hack shop
I talked to a fellow 15 miles away on FM. We wanted to try it.
When he wasn't talking, it was an ungodly static/noise. Audio was very clear.
I can't see me using FM for anything.
When he wasn't talking, it was an ungodly static/noise. Audio was very clear.
I can't see me using FM for anything.
Squelch works well on fm. On my lincoln 2 + it works better than the am squelch. It does not help you much if any to run the squelch open on fm due to the nature of the constant amplitude you either hear them or you dont.
FM has a capture effect, the stronger signal will override the weaker and you won't get the combined signal as you get on AM.
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Most CBs use AGC level squelch, where a signal has to get over S5 or whatever the Squelch is set to, before it opens the audio.
FM in a VHF or UHF Ham Radio uses FM Noise Activated Squelch. This takes the random high frequency noise that an FM detector puts out in between signals, then when a signal is received, the detector goes "Full Quieting".
I have such a Noise Activated Squelch circuit on my drawing table right now. As a possible add-on board for these new (and pre-existing radios (like my HR-2510 hint hint?) It would need to tap into the direct Discriminator output pin of the FM detector, before the pre-emphasis components.
Flip, rotate, top layer component or bottom? Via's? Flip again, rotate, make it as tight as possible. I stage the components outside of the ground planes (red on top layer, blue on bottom layer), so I can see the air wires before moving them inside of the ground planes. I do not like silkscreen on my boards (I remove the silkscreen files from the Gerbers when I submit), so I embed the terminal identification tags in the copper. I am no where near done, yet. Soon, though. I need to figure out a way to disable the AGC part of the original Squelch circuit so this one takes over (in FM).
FM in a VHF or UHF Ham Radio uses FM Noise Activated Squelch. This takes the random high frequency noise that an FM detector puts out in between signals, then when a signal is received, the detector goes "Full Quieting".
I have such a Noise Activated Squelch circuit on my drawing table right now. As a possible add-on board for these new (and pre-existing radios (like my HR-2510 hint hint?) It would need to tap into the direct Discriminator output pin of the FM detector, before the pre-emphasis components.
Flip, rotate, top layer component or bottom? Via's? Flip again, rotate, make it as tight as possible. I stage the components outside of the ground planes (red on top layer, blue on bottom layer), so I can see the air wires before moving them inside of the ground planes. I do not like silkscreen on my boards (I remove the silkscreen files from the Gerbers when I submit), so I embed the terminal identification tags in the copper. I am no where near done, yet. Soon, though. I need to figure out a way to disable the AGC part of the original Squelch circuit so this one takes over (in FM).
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I can report the old tip120 variable power mod works good and does not harm the fm.
What does VR7 do? It looks like it might possibly be the FM Deviation control, seeing as it is near the PLL/VCO daughterboard. Have you tried to adjust it, listen on another radio, see if that is it? Then put it back if it isn't.