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CB FM Mode

Enterprise312ok

Active Member
Jun 12, 2022
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Been using fm mode on my new lincoln 2 today and made several contacts on 26.805. Now I really want to get going on my president J.F.K. restoration.
Also to answer my own question from earlier in the thread: sweep tubes work great for fm ;)
 
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whiteastro

Sr. Member
Feb 22, 2019
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Well this old country boy decided to take my little Thomas Am/FM FCC radio down to the city of Scranton today to give it a spin in more radio traffic and see if I could check out the FM mode better. The results is the Thomas is a good little AM radio but Mine at least is Garbage in the FM mode because AM channels bleed over on to FM channels. While checking FM a couple time I thought I found people talking on FM but they were rather faint and I couldn't get anyone to answer me. The last time I found a man and woman talking and could understand their conversation but it was distant sounding and this was on Channel 32 FM so I switched the radio to AM and there they were Loud & Clear. (n)
 
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Rwb

tell the devil im gettin there as fast as i can,r
Jun 30, 2018
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Well this old country boy decided to take my little Thomas Am/FM FCC radio down to the city of Scranton today to give it a spin in more radio traffic and see if I could check out the FM mode better. The results is the Thomas is a good little AM radio but Mine at least is Garbage in the FM mode because AM channels bleed over on to FM channels. While checking FM a couple time I thought I found people talking on FM but they were rather faint and I couldn't get anyone to answer me. The last time I found a man and woman talking and could understand their conversation but it was distant sounding and this was on Channel 32 FM so I switched the radio to AM and there they were Loud & Clear. (n)
on my galaxy 99v i never got more than white noise. couple of us tried fm n said never again. after it become legal to use fm tried it with my lincoln ii n still nada
 
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whiteastro

Sr. Member
Feb 22, 2019
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on my galaxy 99v i never got more than white noise. couple of us tried fm n said never again. after it become legal to use fm tried it with my lincoln ii n still nada
All I can say is that is the 2nd Brand New President radio I had trouble with. Not a Good track Record so far. (n)
(n)
 
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whiteastro

Sr. Member
Feb 22, 2019
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President Radio has a place where the Sun Doesn't Shine and that would be a good place to put their Thomas & McKinley !!! LOL
 
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Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
16,921
11,221
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Nova Scotia,Canada
Well this old country boy decided to take my little Thomas Am/FM FCC radio down to the city of Scranton today to give it a spin in more radio traffic and see if I could check out the FM mode better. The results is the Thomas is a good little AM radio but Mine at least is Garbage in the FM mode because AM channels bleed over on to FM channels. While checking FM a couple time I thought I found people talking on FM but they were rather faint and I couldn't get anyone to answer me. The last time I found a man and woman talking and could understand their conversation but it was distant sounding and this was on Channel 32 FM so I switched the radio to AM and there they were Loud & Clear. (n)

You do realize that AM and FM use the same channels right? AM will bleed into FM just as SSB does. That does not mean the radio is garbage. Anytime two different modes are on the same frequency or channel there will be bleed. When in FM mode listening to an AM signal the audio will be very low because there is no change in AMPLITUDE to the signal. A trick is to use what is called slope detection where you tune slightly away from the AM signal and this causes the signal strength to actually change as the deviation falls closer to the frequency you are tuned too. It sounds to me like the radio is performing actually as it should but perhaps not as you think it should.
 
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whiteastro

Sr. Member
Feb 22, 2019
601
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You do realize that AM and FM use the same channels right? AM will bleed into FM just as SSB does. That does not mean the radio is garbage. Anytime two different modes are on the same frequency or channel there will be bleed. When in FM mode listening to an AM signal the audio will be very low because there is no change in AMPLITUDE to the signal. A trick is to use what is called sloe detection where you tune slightly away from the FM signal and this causes the signal strength to actually change as the deviation falls closer to the frequency you are tuned too. It sounds to me like the radio is performing actually as it should but perhaps not as you think it should.
I have all the confidence in what your saying as true but if that is the case than FM is of No Interest or Use to me. But thanks for enlightening me and it is back to SSB for me. LOL
 
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towerdog

one-niner-seven
Nov 18, 2009
644
127
53
NC
Don't take this the wrong way, I love AM mode when its done right. Loud, clear booming audio weather it be scanning the air band. talking on the CB with a station out in the Mohave to listening on a vintage tube radio to an AM broadcast station. A strong signal with the right hardware can almost match FM, except it being mono it can maybe even beat it for fidelity over a wide range of amplitude. But any AM radio I have seen made since the 70s or early 80s sucked. FM can deliver decent quality audio from a single chip. To do the same with AM requires a pile of circuitry, and that becomes costly. On our CB radios some stations get it right, but most sound like twangy overmodulated, distortedm booming loud crap. And even though AM is fun for quasi ham DX or local nets, to use the CB to get anything done its worthless. It is true that AM is intelligible at a lower signal level than FM, but you just about have to turn the squelch off to hear it. It might work on the VHF airband but not the upper end of HF. With FM you can run CTCSS / DCS coded squelch. Shuts all the people using AM, all the splattering truckers, all the superhetrodyne noise, the leaky CATV, the traffic lights, shuts em all up. Now folks can actually use the citizens band for it's original purpose. I have used this setup for years and it works. If you are in range of my base or my truck I will hear you, I dont have to turn the squelch up going through town and from base to mobile no amp I can easily talk 30 miles. I could do the same with AM, maybe a few more miles range, but with the squelch open blaring noise.
 

whiteastro

Sr. Member
Feb 22, 2019
601
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I don't take things the wrong way, I join forums to learn more about subjects that interest me. After all none of us can know it all about everything. So who better to ask than the pros who have dedicated more time to a certain area. You'd be surprised to see how many different type forums are bookmarked on my computer. Some would say I am Unfocused, Some would call it Multi-tasking. I call it preparing for the point in life when I can no longer travel and get around and do the other things I enjoy. Have a mighty fine day !
 

AudioShockwav

Extraterrestrial
Staff member
Apr 6, 2005
7,660
5,604
593
Sierras Near Yosemite National Park
My brother and I use FM often, 60 air miles between us with no problems.
Lots of people in the hobby had swr-watt- modulation meters here, almost no one had a fm deviation meter.
Many users did/do not understand that it is not like am were you can turn up audio to insane levels.
Too much on FM means you get outside of the channel spacing and it just goes away.
The guys in the uk understand this because they started on FM from the get go.
I am sure there are a ton of exports out there that the FM controls are set too wide or not properly aligned for FM use because for so long, no one used that mode.

73
Jeff
 

whiteastro

Sr. Member
Feb 22, 2019
601
700
103
71
It can be a fun hobby for sure but too bad we are all spaced so far apart. I don't mind helping others, we all need help sometimes. Like the old saying goes. What you don't have in your head you end up paying for with your wallet. I'm sure glad I only invested in a Thomas instead of a Lincoln II+ to learn FM wasn't for me. The well could run dry!. Had fun today hooking up my new continuous 55 watt power supply and KL 503 but my journey is about over. Seen about 300-400 watts going out on SSB and that will have to be enough.
 
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Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
16,921
11,221
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Nova Scotia,Canada
I have all the confidence in what your saying as true but if that is the case than FM is of No Interest or Use to me. But thanks for enlightening me and it is back to SSB for me. LOL

I honestly have no idea why you just dismiss FM because of the way it works. Not sure just what your expectations are. It sounds to me like you are put off because an AM signal is next to impossible to understand when on FM and vice versa. Well no kidding if that is the case. If not, my apologies. FM to FM is very clear and sounds better than AM actually.
 

whiteastro

Sr. Member
Feb 22, 2019
601
700
103
71
I honestly have no idea why you just dismiss FM because of the way it works. Not sure just what your expectations are. It sounds to me like you are put off because an AM signal is next to impossible to understand when on FM and vice versa. Well no kidding if that is the case. If not, my apologies. FM to FM is very clear and sounds better than AM actually.
I might change my mind if I make a direct FM contact but maybe FM hasn't caught on around here yet. CBs in general aren't used that much around here. I'll probably just have to get more patient. Thank for bearing with me !
 

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