K3: Poor AM receive audio quality

[VK5ABQ]

Relative to my 1983 Kenwood R-2000 (http://www.rigpix.com/kenwood/r2000.htm), my K3 sounds awful when listening to any AM broadcast stations. I have the 6KHz and 12KHz filters installed and despite widening the AM IF bandwidth to 10KHz and spending many hours fussing about with the RX EQ, I cannot make the K3 to sound even remotely enjoyable. Quite frankly, this is really annoying me although I am impressed by the K3 thanks Elecraft.

I've ordered an Icom SP20 in the hope this will help but while waiting for it to arrive I did some research and stumbled on this archived thread - http://www.mail-archive.com/[e-mail]/msg52230.html, which suggests the K3's DSP attenuates the IF passband below 250Hz and the frequency range of the IF passband will be widened in a firmware upgrade.

So I have the following questions -
Why have the low frequencies been attenuated?
Is 250Hz the -6dB or -3dB point?
Will the passband be widened in an upgrade?

I do admit though that the K3's SSB audio is FAR superior to that of the R2000 (but it does have a VFO resolution of only 100Hz). The K3's SSB audio does sound great.

Shane
VK5ABQ

[Dave, G4AON]

Shane, you will probably find external speakers transform the quality of
the K3. I am using a cheap pair of HiFi book shelf speakers that cost
under 20 GBP and it sounds great on local AM broadcast stations using no
RX EQ and 6 KHz IF filter. In side by side comparisons with a Perseus
SDR and fairly cheap PC speakers on my PC, the K3 sounds much better,
with the internal K3 speaker the opposite was the case. The speakers I
am using are from a UK high street chain store, www.argos.co.uk and
stock number 513/6113.

You might want to try a pair of speakers, as the pseudo stereo effect of
AFX is amazing.

73 Dave, G4AON
K3/100 #80
-----------------
Relative to my 1983 Kenwood R-2000
(http://www.rigpix.com/kenwood/r2000.htm),
my K3 sounds awful when listening to any AM broadcast stations. I have the
6KHz and 12KHz filters installed and despite widening the AM IF bandwidth to
10KHz and spending many hours fussing about with the RX EQ, I cannot make
the K3 to sound even remotely enjoyable.

Shane
VK5ABQ

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[AD6XY]

You are right, even with an external speaker. I would not say it is bad, but my THS480 is much better, as is my SDR IQ. Like the difference between a cassette tape and a CD say.

I think the problem is the low frequency response - it could be something to do with the DSP filtering. The  good thing is, it can be changed. For comms, you do not need full frequency response. The K3 is designed primerily for communications.

Mike

[VK5ABQ]

Thanks for your replies guys. Hopefully Icom's SP20 makes a difference.

I've received too many emails privately to reply to each separately sorry so I hope those who were kind enough to spend their time writing to me won't mind if I answer all questions here?

I do have a KBPF3 general coverage bandpass filters installed and my comments about the relatively poor audio quality referred to the sound coming from the K3's internal speaker. While the R2000 sounds terrific using a 6KHz max bandwidth to listen to AM broadcast, the K3 just does not sound very nice at all despite being opened up to 10KHz bandwidth. I couldn't believe how poor it sounded when I turned the rig on the first time (it was factory assembled). I had that sinking feeling you get when you first suspect you've not spent your money on what you should have.

At this stage I do expect the K3 will sound fine with the SP20, after all 50Hz and 100Hz were included in the RX EQ for a reason? It's a pity their level doesn't make any difference when listening to the K3's internal speaker.

[Ken Kopp-3]

Hello Shane,

Assuming there's nothing wrong with your internal
speaker or it's mounting.... I still wouldn't expect it
to sound very good. I view that little speaker as little
more than a device to tell if the radio's working or not,
and not suitable for listening.  

If you haven't done so, try an external speaker, or
better still, two.  The AFX feature is really nice. After
all the K3 -is- a "communications" transceiver. (:-)

73! Ken Kopp - K0PP
[hidden email]

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