Hi guys,

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I would like to install a DSP filter, who can tell me where the advantages and disadvantages are between the sotabeams filter LASERBEAM-817(FTFM-100) and the BHI filter NEDSP1901-KBD. Is it possible to operate the sotabeams filter from the outside, whereas the BHI filter requires two holes to be drilled.?

Vy 73 de Martin HB3YDM

I have no experience with the BHI filter, however I installed the sotabeams filter in my 817 and it's great.

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All filter switching is controlled from the buttons on the radio. You do have to move the speaker over slightly inside the housing to make space for the module though.

Mike Davis WA1MAD

Hi Mike, check YouTube, I think he has an or mor Videos See under ?Sotabeams FT-817“ I hope this helps for your search on YouTube.

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73 de Martin, HB3YDM

Another option is the external 4StatesQRP HI-PER-MITE audio CW filter kit . ?This filter ?is 200 Hz wide and has no ringing - a truly ?amazing 4 pole filter with 3 low pass filters and 1 high pass filter cascaded together. ??

All background hiss is essentially eliminated when the filter is engaged. ?

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Google ‘HI-PER-MITE’ for more info including an audio demo of this CW audio filter in action.

I had the laserbeam filter unit installed in my 817nd for a while. It does work but has a couple of annoying side effects. Well, at least mine did.

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First, the metering for signal strength is thrown way off. Not the end of the world, but a bit nippy.

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Second, and most annoyingly, the filter creates ghost images of strong signals. These were a couple of kHz away from the actual signal. I can't remember the exact offset but it was a pain in the hoop to constantly flip the filter in and out of line to see if I was listening to a real signal or an image. This could partially be worked around by using the IF Shift on the radio.? The filter was installed exactly as per the instructions. I am very comfortable working with surface mount components and have confidence in my work. I even removed and re-installed it in case there was some hidden issue with my work but that made zero difference.?

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The second issue was annoying enough for me to eventually remove the filter and throw it in the bin. I approached sotabeams about the issue at the time but they were less than energetic in their response.

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I eventually managed to source a 500Hz Collins mechanical filter for a VERY reasonable price and use that in the radio. The difference is night and day!

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Given the current cost of mechanical filters, I'd go for the BHI option.?

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This is just my experience and I'm sure others are happy with the laserbeam. It is cheap after all.?

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Cheers,?

Ronan

MM0IVR?