Yaesu FT 817 / CW Filter Modul

Hello Sota friends, in the last post I wrote that I plan to activate my Yaesu FT 817 in CW in the future.

I received the TRX used, so far I have only ever done SSB. Today I took a look to see if this has also been expanded for CW.

When I opened the lid I could discover a built-in Sotabeams CW module, a muRata CFJ455K /8 filter, which is plugged into the optional filter slot and a TXCO unit.

I was very happy that it appears to have been expanded for CW.

In the TRX menu it is activated that the optional filter is active in CW.

However, I don’t understand the connection between the Sotabeams module and the Murata module on the optional slot.

According to the data sheet, the Murata module has a bandwidth of 1 kHz.

If I now switch the TRX from SSB to CW, I notice acoustically that the SSB images are deactivated and the filter is narrower.

If I remove the optional Murrata filter, no NF comes out at all.

But what is the point of installing the Sotabeams module with the Murat 1khz?

I would like to know whether the bandwidth in CW is 500 kHz or 1 kHz?

With the Sotabeams module I saw that this is available in SSB and also in CW. In addition, the small button is missing on this one. Can I see if the module is for CW or SSB?

Many thanks for your help.

73 Greetings Michael

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The optional filter is enabled by two things. One in the extended (long press of F key) menu where you tell the radio whether the optional filter is installed or not and whether it is for cw or ssb. Yours would be selected for the cw filter.

Then, when using the radio and you press the NAR option in the first level menu (short press of Function key) the optional filter is engaged. Press NAR again to switch it out.

The sotabeams filter operates at audio frequencies and if I read your info correctly has the ssb and cw options. You would use both the optional filter at 1 kHz bandwidth and the sotabeams filter in narrow bandwidth for best filtering of QRM in cw.

But you can use whatever combination you like.

The murata filter helps by reducing the QRM from strong nearby signals. Without it in circuit those strong nearby signals can reduce the gain in the receiver, causing a weaker signal to be reduced as well as everything else in the passband of the receiver.

But you know you can leave all the filters out of circuit if there is no nearby QRM. Cw still works fine without the filters.

If you configure the rig with the filter option in the menu, but don’t have a filter installed. pressing NAR switches the signal to a nonexistent filter so the receiver goes quiet.

Study the manual for more details of how to set up the optional filters.

The sotabeams filter does a great job and now that the original Collins filters are no longer made, they are a great option for these radios.

73 Andrew VK1DA/VK2DA