K3 General Coverage Recieve

[BReese]

I just installed my General Receive Option on my K3, and it seems the audio quality on AM radio freqs (640-1070) are very poor quality. I'm i missing something? Did i get the right option for listening to AM radio? OI have the default filter that came my K3.

Thanks

[Julian, G4ILO]

BReese wrote

I just installed my General Receive Option on my K3, and it seems the audio quality on AM radio freqs (640-1070) are very poor quality. I'm i missing something? Did i get the right option for listening to AM radio? OI have the default filter that came my K3.

If you want to listen in AM mode you should have got the optional 6KHz filter as well. Try using USB or LSB and zero beat the carrier.

[AD6XY]

Most of these AM transmissions in the UK are very poor quality to begin with. Not just the content, but also the audio compression and filtering. The better the quality of the radio you use, the more you notice this.

[Julian, G4ILO]

AD6XY - Mike wrote

Most of these AM transmissions in the UK are very poor quality to begin with. Not just the content, but also the audio compression and filtering. The better the quality of the radio you use, the more you notice this.

I don't see why this would be specific to the UK (and I didn't think the OP was referring to British stations in any case.) Short wave broadcasters use a 5KHz spacing so the transmitted bandwidth is bound to be below hi-fi quality. The use of compression is probably also normal to maximize readability under poor conditions.

[AD6XY]

Yes - but where the UK leads....  at least in the US they get the voice of reason on AM for ironic entertainment. All we get is 5 live and a few local radio stations.

In terms of audio quality, I think there has been a reduction in recent years. It is AM so it does not matter sort of attitude. Yes there will be a limit at around 3kHz with the 6kHz filter on the high frequencies but whenever I listen there is a lot of mush lower down on broadcast radio transmissions these days. You might expect at least the bass to be good but often it isn't as it tends to require more of the transmitter power - so for something to sound loud bass is cut and midrange boosted. For speech fine but the same settings are no good for music.

Back to the K3. The correct filter to listen to AM broadcasts will be the FM filter. 6kHz is too narrow, it is designed for amateur transmission. A 10 kHz filter would be better but I am sure the DSP can cope with removing the leakage from adjacent channels due  to the 15kHz filter.

Mike

G4ILO wrote

AD6XY - Mike wrote

Most of these AM transmissions in the UK are very poor quality to begin with. Not just the content, but also the audio compression and filtering. The better the quality of the radio you use, the more you notice this.

I don't see why this would be specific to the UK (and I didn't think the OP was referring to British stations in any case.) Short wave broadcasters use a 5KHz spacing so the transmitted bandwidth is bound to be below hi-fi quality. The use of compression is probably also normal to maximize readability under poor conditions.

[Julian, G4ILO]

AD6XY - Mike wrote

Yes - but where the UK leads....  at least in the US they get the voice of reason on AM for ironic entertainment. All we get is 5 live and a few local radio stations.

In terms of audio quality, I think there has been a reduction in recent years. It is AM so it does not matter sort of attitude. Yes there will be a limit at around 3kHz with the 6kHz filter on the high frequencies but whenever I listen there is a lot of mush lower down on broadcast radio transmissions these days. You might expect at least the bass to be good but often it isn't as it tends to require more of the transmitter power - so for something to sound loud bass is cut and midrange boosted. For speech fine but the same settings are no good for music.

Back to the K3. The correct filter to listen to AM broadcasts will be the FM filter. 6kHz is too narrow, it is designed for amateur transmission. A 10 kHz filter would be better but I am sure the DSP can cope with removing the leakage from adjacent channels due  to the 15kHz filter.

I thought we usually followed the US lead. But I was thinking of the short waves anyway. I don't know why anyone would listen to local radio using a K3 when they can get the same stations on a five quid VHF FM portable. (Mind you, much of the point of SWL seems to have gone thanks to the advent of internet radio. Before switching the K3 on I was listening to classical music from WCPE in Raleigh, NC at FM quality!)

You may be right about using a wider filter, though the 5KHz heterodynes would be a bit irritating. Perhaps the notch would remove them. I was going to try it, since I installed my FM filter this morning, but even though the CONFIG menu shows FL1 is ON in AM mode, the width control won't go above 3.00. I guess that's another one of those firmware mods we're waiting for.