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Radiodude
Advanced Member
Username: Radiodude
Post Number: 597
Registered: 1-2002
| | Posted on Saturday, June 11, 2011 - 10:20 pm: | 
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I am in a discussion with a guy in the UK. He is telling me that FM Cb is better than AM Cb! He tells me that he can talk 200+ miles on FM any time he wants! I am telling him NO WAY! I know they are on different freqs than us BUT 200 miles with 4 watts on FM? What are your thoughts on this!
Ernie
KC8YOQ
Copper 123
Walkie Talkie
2NA750
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Moonraker
Intermediate Member
Username: Moonraker
Post Number: 277
Registered: 3-2005
| | Posted on Sunday, June 12, 2011 - 10:49 am: |
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I really like the quality sound that FM has but it doesn't have the range he says it does. I used to talk to some guys on SSB about 40 miles away with no problem. We switched to FM one night and could barely hear each other. We were talking on bases BTW. |
Ronin
Member
Username: Ronin
Post Number: 86
Registered: 8-2006
| | Posted on Sunday, June 12, 2011 - 12:38 pm: |
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Basically, SSB will give you the greatest range mostly because of it's narrow bandwidth. FM will give you nice communication grade audio (with a good radio that has a good FM circuitry), sort of like listening to a police scanner or business radio. AM has the ability to tweak the audio components to get a nice sound and more options for getting the audio that you want. What sounds good on AM usually does not sound too good on FM or SSB. My preferrence is SSB, but it is nice to have AM and FM as well for when you want to use it.
Jim
CEF-813
K3ZOR
OT-235
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Radiodude
Advanced Member
Username: Radiodude
Post Number: 598
Registered: 1-2002
| | Posted on Sunday, June 12, 2011 - 1:46 pm: |
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Yup that is what i thought! I can FM also and it just does not have the range. Local it is a nice mode!
Ernie
KC8YOQ
Copper 123
Walkie Talkie
2NA750
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Tech833
Moderator
Username: Tech833
Post Number: 1990
Registered: 8-2002
| | Posted on Monday, June 13, 2011 - 12:21 am: |
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FM is far superior to SSB in local comms. Both for sound quality and for noise rejection.
SSB works good for DX because you can still get intelligible audio from very weak signals with the squelch all the way off and with deep QSB.
Your radio 'Mythbuster' since 1998
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Tech237
Moderator
Username: Tech237
Post Number: 1445
Registered: 4-2004
| | Posted on Monday, June 13, 2011 - 9:28 pm: |
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Wth good conditions you can work long distance using fm, like 2500 miles on 2m FM using 5w. OK it WAS during a tropospheric duct. I have also regularly had 150 mile plus contacts on 10M - when the conditions were right. IN fact looking at my log I have one 7,500 mile contact on 10M FM - Baker City OR to Brisbane Australia, it lasted for around 15 minutes, and yes that was in 99 during the peak conditions.
Tech237
N7AUS
God only made some many perfect head, on the rest he put hair.
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Tech858
Moderator
Username: Tech858
Post Number: 378
Registered: 10-2007
| | Posted on Tuesday, July 05, 2011 - 7:09 am: |
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Radiodude
There is no way that that guy can talk 200+ miles any time he wants , ok when conditions are in our favor then as Tech237 said it is possible to work some very long distance but most of the time over here in the UK it is mainly possible to talk at most 20 miles on FM and that is with a real good antenna if you are running a little bit of power , the UK freqs are at the top of the 11mtr band from 27.60125 - 27.99125 so it is more like 10mtrs conditions the higher up the channels you go .
Tech858/Jim
CEF#0858 ~ CEF HAM#0230
CVC#0116 ~ MM0TXO
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Dale
Senior Member
Username: Dale
Post Number: 1734
Registered: 12-2002
| | Posted on Tuesday, July 05, 2011 - 8:01 pm: |
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i like fm also. but after 20 miles out or so
i cant keep the squelch just closed so noise
just disappears anymore.gotta run it wide open
after 20 miles i cant break the squelch anymore
love my magnum on fm though
dale/a.k.a.hotrod
cef426
cvc#64
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Rover
Intermediate Member
Username: Rover
Post Number: 496
Registered: 2-2004
| | Posted on Wednesday, July 06, 2011 - 5:22 pm: |
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The thing about FM is, it requires much more bandwidth than SSB. That's why they discourage its use below 30 MHZ. Even then it is merely experimental WRT amateur communications on 29 MHZ. I can only listen to the racket and clashing signals for a few minutes at a time. YEESH!  It causes so much interference to other stations plus the distance....it messes up too many stations far away. It's why it has widespread use above 30 MHZ. |
Kiwikid
Intermediate Member
Username: Kiwikid
Post Number: 222
Registered: 1-2003
| | Posted on Wednesday, July 13, 2011 - 10:41 pm: |
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I wonder whether someone,pardon the pun, has got their wires crossed.Possibly the referance to FM maybe related to repeater operations in which case 200 miles is quite possible |
Moderator120
Moderator
Username: Moderator120
Post Number: 703
Registered: 11-2006
| | Posted on Monday, July 18, 2011 - 12:36 pm: |
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Given the choice, I would work FM, it just sounds so good. But in the real world, AM is more usable, just my 2 cents!
Mike 
Moderator120
CEF#0120/HAM #222
KB1NYD
CVC#0041
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Onelasttime
Junior Member
Username: Onelasttime
Post Number: 17
Registered: 8-2011
| | Posted on Thursday, August 11, 2011 - 6:42 pm: |
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Their is a reason that AM was used for the longest time for radio broadcasting's!!!It's propagation characteristically are far better then FM. This is why you could hear a 20,000 watt AM station in California at night time on a radio in Michigan during radio's golden days. If you look at FM broadcasting sure it has more fidelity then AM but they have to use 50,000+++ watt's or more for a radio station that is just barely able to be heard in say 3 cities in a given State. Like wise FM does not get the huge jump in propagation hat AM does after sunset.
Their is a reason that most of the stuff you pick up on world band short wave radio's is not FM. Also a reason why the Radio Free America and Radio Free Europe where AM and using insane amounts of power so they could be heard every where on earth! FM can not do that with out repeater's or the like. Since SSB is basically one side of a AM signal it behaves much the same only more effeiecent!
Their is no way with that anyone inthe UK is talking 200 miles on 4 watt's on FM unless they are hitting repeater's or as CB'er's would say " the skip was running"!!! I talked from Georgia to London and USSR and Trinidad from a stock 2950 with a 102 inch stainless steel whip. It is not because of the radio it was because of the sun spot cycle at the time.
In fact I would bet dollars to doughnut's that the UK and other countries that let people use FM as a hobby 2way band like our AM CB set up is because FM propagates less and is less likely to cause interference with other items like TV set's, cordless phones and the like. |
Tech833
Moderator
Username: Tech833
Post Number: 2028
Registered: 8-2002
| | Posted on Friday, August 12, 2011 - 11:26 am: |
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You have confused MODE with BAND.
AM is Amplitude Modulation mode. The carrier is modulated by changing the transmitter power output at an audio rate. To make a waveform, the transmitter power is increased and decreased accordingly. The frequency of the carrier stays the same.
FM is Frequency Modulation mode. The carrier is modulated by changing the frequency at an audio rate. To make a waveform, the frequency is increased (higher freq.) or decreased (lower freq.) accordingly. The power of the carrier stays the same.
The AM broadcast and Shortwave bands are in the MF (Medium Frequency) and HF (High Frequency) bands. These bands below 30 MHz. are subject to refraction and reflection from layers of the ionosphere (the Earth's atmosphere). At night, lower frequency signals travel further. During the day, high frequency signal travel further. This is a discussion way too long for this thread. A web search will provide all the education you need.
The FM broadcast band is between 88 and 108 MHz. in the VHF (Very High Frequency) range. VHF signals do not refract or reflect off of the ionosphere layers like MF and HF signals do. This is why they are limited to line of sight (groundwave) only. I will not go into seasonal E-layer skip here.
You can run FM mode on the MF or HF bands and get the same amount of coverage as if you used AM mode. It's the band that gives the propagation characteristics, not the mode.
As an example, some hams use AM or SSB mode on the 2-meter VHF ham band. It propagates the same as if they were using FM mode, with few exceptions. The main reasons for using the AM or SSB modes on VHF are because they are using vintage equipment, and because the mode is more spectrum efficient. DXers prefer SSB mode because a weak signal can be tracked through varying (QSB) conditions more easily due to the very narrow receive filters that can be used for this mode, which allows greater sensitivity.
Your radio 'Mythbuster' since 1998
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