Saturday, 1 May 2010

CW Machine

I mentioned in an earlier blog that, in my view, the FT817 needs an IF filter to be useful for CW (without it, it doesn't match my Funster Plus on 40m).

Well - I'm pleased to report that I now have one - and that it works a treat!

Regular readers won't be surprised to hear that cheapskate/"tightwad" m0xpd was depressed to see the prices for CW filters, some of which (taken from the 'net today) are shown below...

Martin Lynch & Sons£118.48
Waters & Stanton£89.95
W4RT$114 + Shipping

However, Julian, g4ilo, commented on this blog that Jim, k8drn, supplies filters at a very competitive price. I contacted Jim, who quoted $110 including delivery to the UK - so I placed an order!

The fall-out from Icelandic volcanos introduced a little delay into the delivery, but the part duly arrived, in good protective packaging (the XYL has her eye on the nice tin)...

The filter board itself...

is very easy to plug into the main board of the FT817, following the instructions in the Operating Manual...

(in fact the only difficulty was figuring out how to re-fit the Palm Radio "Peg Leg" tilt stand kit on my FT817).

All seemed OK on the mechanical side - but when I tried to use the filter for the first time I came unstuck.

The Operating Manual instructions (page 74) told me to ...

"Change the setting of Menu #38 (OP FILTER) to "SSB" (if installing the YF-122S), or "CW" (for the YF-122C/F-122CN).

When I tried this, there was no audible change on setting CW and an audible change on selecting "SSB" - this audible effect threw me!

Here's a snapshot of the spectrum of the audio from the FT817, in CW mode at the high end of the CW segment of the 40m band this morning, with Menu #38 in "OFF" mode (captured, for convenience, by CWGet)...

It shows wideband noise (- the wide-open response which is exactly the reason the CW Filter is needed). When I selected "CW" in Menu #38, exactly the same noise spectrum was heard.

When, however, I selected "SSB", the following signal was produced...

This noise has been filtered by exactly the expected bandwidth - but at the wrong centre frequency. I was confused!

Thankfully, Julian g4ilo came to my rescue, sending this link to some clear step-by-step instructions by Dave Fifield, AD6A, for filter installation. Fortunately, these go one VERY IMPORTANT step further than the instructions in the Operating Manual - and sorted my problem. Dave's key final step taught what I had failed to spot: that it is also necessary to select "NAR" in row 7 of the function options "buried" in the "A,B,C" buttons.

Here's the resulting 40m noise spectrum (indicating the expected frequency response of my new filter)...

That's better! Thanks Julian! Thanks Dave, ad6a!

I gave it a try with a quick qso with a special event station, gb0fsg, "Celebrating 100 years of Fochabers scouts from Inchberry near Fochabers", operated at the time by Don.

I continue to be really impressed by the FT817 (though not by its Operating Manual).

Now I am also very impressed by Jim, k8drn's filter - great service, great product, great price.

Thanks Jim!

...-.- de m0xpd


  1. Hi, I looked up W8DRN in google and didn't get anything sensible. Also W8DRN isn't listed at Is the call a typo or am I missing something dumb? Thanks Steve

  2. Thanks for your comment, Steve. The mistake is all mine - Jim's call is k8drn. At least, according to, Jim's call is now k4drn - but he WAS k8drn and his email address still starts with "k8drn". Sorry to you and to Jim! I've corrected the Blog entry - but thanks for pointing out my dumb mistake!