We have all gone fm and everyone says they hear me great but all I hear is the same louder interference. Could someone explain how fm works and what am I doing wrong. Thanks!!
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
My President has FM hjow does it work?
- Thread starter hammer0630
- Start date
I would guess that a lot of the export radios added FM is an after thought and is using circuits that where made for AM, and they need to filter out all the amplitude modulation then they have a FM part that will decode the frequency modulation. You are still hearing the same interference pass through because it is not getting all the AM out...
What do you hear when you tune in to an AM station in FM mode? I know on my RCI-2990 people can hear me on AM when I am in FM mode...
I don't know the answer I am just taking a crack at it.....
What do you hear when you tune in to an AM station in FM mode? I know on my RCI-2990 people can hear me on AM when I am in FM mode...
I don't know the answer I am just taking a crack at it.....
Please define "interference". FM will have a constant hash noise like static and it can be loud so you do need to use the squelch control. If you are getting other stations then that is normal if they are really close or on the same frequency.
The only different between modes is the detector circuit.Everything else is the same in any radio. By it's nature an FM detector does not demodulate AM very well at all but you can still hear FM on an AM receiver by what is called "slope detection". As the frequency of the signals varies up and down in frequency according to its modulation, the signal moves up and down within the passband of the receiver's filter. This causes the amplitude of the signal to vary in line with the frequency variations. In fact at this point the signal has both frequency and amplitude variations and an FM signal can be heard for this reason.
You will never be able to 100% completely reject another mode.
RatsoW8
Supporting Member, W9WDX ARC Member - WD8T
I have yet to run into a 2510 that hasn't been modded, snipped, clipped, tweaked, peaked, twiddled and diddled to CB wonderment.
yes several people or all say they hear me great all I hear is the higher hiss and buzz but I do see their signal readings the same but no audio?
Sounds like Bob may be on to something there. This may not be the reason in this case however it is the reason why I detest it when people that don't know their ass from a hole in the ground when it comes to working on gear start screwing around with a nice radio and end up screwing things up. My take is if you don't know cause and effect when you adjust something then leave it the hell alone.
Sorry, my rant is not directed at you but rather at all the 11m screwdriver cowboys out there. Well...... unless you are a screwdriver cowboy yourself. :laugh:
OK so I now know from you guys the elevated FM hiss is normal I was also asked on what frequency I was trying on I don't remember does this mean that FM only works on certain freeks? When I was observing my receive meter when we all tried fm I could see that I was receiving them but the fm hiss did not change in any way. Also the HR2510 has been modded by the fact it works well on 11 meters but I am pretty certain their is no chip switch and the audio is louder on AM "which I am to believe these are not known for loud am modulation" than almost every local here and that's about 20 bases I talk with and I can't name one with a unmolested radio. As I may have already stated I have never owned a radio with FM before and Google had no info either...Thanks guys!
FM on the HR2510
FM is a different mode from AM or SSB, FM will reject signals that are AM and at best will allow only a scratchy noise and you might hear some modulation.
All those in QSO should be on FM mode for it to work properly and by using the squelch the loud background hiss or static will be gone. Only good signals will be heard over the squelch.
FM mode also has what is called 'capture effect' and that means stronger FM signals will be heard over weaker ones. Long distance will lesson the ability of your transceiver to 'hear' signals and DX or 'skip' with it's fading will worsen this.
With the the USA FCC's rules, FM is not allowed below 29.000 mHz. Exceptions to this are a few remote broadcast linking stations, example of this would be a studio link of a ball game. These frequencies would be around 26.100 mHz.
FM will 'work' on any frequency but is used mainly above 29.000 mHz as it is a wide mode, it uses up a bit of 'channel' bandwidth somewhat more than an AM signal and much more than a SSB or CW signal.
The FM mode of the HR-2510 is narrow mode and if not properly adjusted or if the AM modulation is 'over' done, the FM signal will not be very good and will splatter. :headbang
73 mechanic
FM is a different mode from AM or SSB, FM will reject signals that are AM and at best will allow only a scratchy noise and you might hear some modulation.
All those in QSO should be on FM mode for it to work properly and by using the squelch the loud background hiss or static will be gone. Only good signals will be heard over the squelch.
FM mode also has what is called 'capture effect' and that means stronger FM signals will be heard over weaker ones. Long distance will lesson the ability of your transceiver to 'hear' signals and DX or 'skip' with it's fading will worsen this.
With the the USA FCC's rules, FM is not allowed below 29.000 mHz. Exceptions to this are a few remote broadcast linking stations, example of this would be a studio link of a ball game. These frequencies would be around 26.100 mHz.
FM will 'work' on any frequency but is used mainly above 29.000 mHz as it is a wide mode, it uses up a bit of 'channel' bandwidth somewhat more than an AM signal and much more than a SSB or CW signal.
The FM mode of the HR-2510 is narrow mode and if not properly adjusted or if the AM modulation is 'over' done, the FM signal will not be very good and will splatter. :headbang
73 mechanic
I am going with something is out of whack than broken
Attachments
- No one is chatting at the moment.
-
-
dxBot:63Sprint has left the room.
-
dxBot:kennyjames 0151 has left the room.
-
-