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Author Topic: Elecraft K3 with KBPF3  (Read 26557 times)

AD9DX

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Elecraft K3 with KBPF3
« on: June 30, 2013, 07:57:53 AM »

So when I bought my K3 (used) it had the general coverage module in it. My question is, do I need to use an AM roofing filter to get the most out of my SWL experience?
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EX, KC9TRM, KB9IRZ

AD9DX

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RE: Elecraft K3 with KBPF3
« Reply #1 on: July 01, 2013, 04:07:11 PM »

Anyone? 400+ views and nobody knows.
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K0OD

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RE: Elecraft K3 with KBPF3
« Reply #2 on: July 01, 2013, 08:01:33 PM »

Hopelessly vague: "get the most out of my SWL experience?"

If your antenna consists of a log periodic at 100' on the east coast near a VOA transmitting site, an optional roofing filter might be somewhat useful... occasionally. What modes are you referring to? What broadcast services do you listen to? I can see one being useful sometimes for listening to broadcasts in the 40 meter ham band.

Heck, I sometime SWL with one of my 1930s-vintage Zeniths for nostalgia sake. They hear pretty darn well with a hunk of random wire for an antenna. For most listening purposes I'm sure a barebones K3 would be vastly more than adequate.
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AD9DX

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RE: Elecraft K3 with KBPF3
« Reply #3 on: July 02, 2013, 07:50:18 AM »

Hopelessly vague: "get the most out of my SWL experience?"

If your antenna consists of a log periodic at 100' on the east coast near a VOA transmitting site, an optional roofing filter might be somewhat useful... occasionally. What modes are you referring to? What broadcast services do you listen to? I can see one being useful sometimes for listening to broadcasts in the 40 meter ham band.

Heck, I sometime SWL with one of my 1930s-vintage Zeniths for nostalgia sake. They hear pretty darn well with a hunk of random wire for an antenna. For most listening purposes I'm sure a barebones K3 would be vastly more than adequate.


More concerned with whether increased fidelity would come from using a wider roofing filter. Or if the KBPF3 has its own roofing filter that negates that.

Sorry
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K0OD

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RE: Elecraft K3 with KBPF3
« Reply #4 on: July 02, 2013, 12:20:20 PM »

I see a lot of people puzzled by the KBPF3. The info I found was pretty vague. It's not a roofing filter. It's just adds additional band pass filtering for the non-ham bands. Shouldn't affect audio fidelity.

Without it, I guess you might get some IF bleed-thru in some SW ranges. I don't have a K3. I use a Flex-5000. I also have a Palomar longwave converter which outputs in the 4.0 to 4.5 MHz range where the receiver has no BPFing. I can sometimes hear, and can often see on the panadaptor some crud leaking thru.  I would have been better off using a converter with an output in the 3.5 MHz range (80 m ham band) where the Flex has excellent BP filtering. At least with the Flex the problem is pretty minor except below the AM broadcast band (<540 kHz) where the radio picks up nothing but garbage.

I'd ask a K3 Group for more details.  I thought you were looking for narrower selectivity. For good audio I tend to use wide settings of about 6 KHz for SW and Longwave and more than 10 kHz for the AM band.
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N5TU

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RE: Elecraft K3 with KBPF3
« Reply #5 on: July 02, 2013, 02:57:41 PM »

Mine sounds much better with the 6 kHz roofing filter.  Otherwise, you have to tune off and listen to one sideband.

73,
Bill, N5TU
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AD9DX

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RE: Elecraft K3 with KBPF3
« Reply #6 on: July 03, 2013, 08:39:44 AM »

Mine sounds much better with the 6 kHz roofing filter.  Otherwise, you have to tune off and listen to one sideband.

73,
Bill, N5TU


That's what I was looking for. Thanks!
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KE7TMA

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RE: Elecraft K3 with KBPF3
« Reply #7 on: July 03, 2013, 11:23:21 AM »

If your antenna consists of a log periodic at 100' on the east coast near a VOA transmitting site, an optional roofing filter might be somewhat useful... occasionally.

How about a local broadcast antenna farm?  Lots of these transmitters give out spurious images on their harmonics and the FCC doesn't care as long as they don't interfere with another broadcaster in the area.

I get plenty of interference from local broadcast stations with my simple dipole and end fed wire antennas.  The roofing filters in my KX3 are quite useful.
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K0OD

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RE: Elecraft K3 with KBPF3
« Reply #8 on: July 03, 2013, 07:01:50 PM »

Mine sounds much better with the 6 kHz roofing filter. 
73,
Bill, N5TU

As compared with what? No roofing filter or a narrower one?
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AD9DX

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RE: Elecraft K3 with KBPF3
« Reply #9 on: July 05, 2013, 04:12:06 AM »

Mine sounds much better with the 6 kHz roofing filter. 
73,
Bill, N5TU

As compared with what? No roofing filter or a narrower one?

I'd suspect it sounds better than the standard 2.7kHz filter.
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K0OD

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RE: Elecraft K3 with KBPF3
« Reply #10 on: July 05, 2013, 09:24:08 AM »

Mine sounds much better with the 6 kHz roofing filter. 
73,
Bill, N5TU

As compared with what? No roofing filter or a narrower one?

I'd suspect it sounds better than the standard 2.7kHz filter.

Yes, and maybe its better yet with no filter at all if fidelity is what you mainly want.  I think a lot of money is wasted on costly add-on filters. With my Flex, where I can create almost any bandwidth in software, I tend to go with wider filters than one might expect. Even in QRM, there's a lot to be said for not trimming a station's bandwidth too much.

And I have two sideband filters on my old TS-850: I use the stock 2.4 kHz filter over the very costly 1.8 KHz one almost 100% of the time, even in brutal contest conditions.
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