How to Turn a 20+ Year Old Yaesu FT-817 into a CW Mean Machine

It was my very first HF radio. A Yaesu FT-817; the original vintage before the ND version was introduced. I was very excited; it was the perfect solution to serve my passion for getting outdoors into the Big Blue Sky Shack to play radio.

I had a lot of success. My outdoor antenna was a MFJ-1979 17ft telescopic whip. I mounted the whip on top of a pole about 12 feet high. Four radials each 17ft long also served as guy lines to keep my home made 20m ground plane antenna vertical. The radio was powered by a 12V, 7AH gel cell that never seemed to run out of charge. The FT-817 was believed to put out its full 5 watts down to a battery voltage of about 10.5 volts and since I didn’t like to discharge my gel cell too deeply the radio and battery were a perfect match.

SSB Easy, CW Hard

I started my HF adventures as a SSB operator. I had passed the 5wpm CW test that was required at the time to earn HF privileges in Canada, but 5wpm was nowhere near fast enough to give me the confidence to get on the air as a CW operator. Besides, SSB was easy. And I was getting a lot of QSOs every time I went out to the field. I was happy … but then …

Not So Fast!

It wasn’t long before the urge to get on the bands with CW became irresistible, but it took a while to get my speed up to around 14wpm so that I could enjoy QSOs. It took quite a while longer to become proficient at 20+wpm, but that’s another story.

It was quickly becoming clear to me that my humble FT-817 couldn’t cut the mustard in the world of serious CW operating. I learned that lesson very quickly one Field Day when I tried to operate without the benefit of a CW filter. All I heard was the cacophony of multiple QSOs all happening simultaneously while my receiver was pumping out a bandwidth as wide as the mighty Mississippi.

Yes you can (or should I say could) buy a Collins mechanical filter but that wasn’t the only issue I had with the radio. When you operate CW for any extended time you could be calling CQ hundreds of times and that can become very tiring. And tired fists make keying errors – well mine do anyway. I needed a memory keyer to allow me to send repetitive messages like CQ by simply pressing a button. That’s a kinda basic function for most modern radios, but not the Yaesu FT-817.

Adios Old Friend

So, the upshot was, I looked at my FT-817 and told it I needed something better. The front panel of the FT-817 is visually appealing. It’s looks like a contented puppy and I was very fond of it. It sat on a shelf in my home shack looking wistfully at me and I looked back wishing there there was some way I could bring it out of retirement. Well, there was a way, and this is how I did it.

A Memory Keyer

I could have bought a Winkeyer, or I could have used the homebrew version based on K3NG’s design. But I had a better idea. I decided to try something completely different. Ham radio is all about experimentation isn’t it? So I built a memory keyer with unlimited memories! How many commercial memory keyers can claim that?

The design is very simple. The memory keyer is a cellular mobile phone running a voice recorder app. I keyed a selection of CW messages using another radio and recorded them on the phone. I fed the output from the phone’s headphone jack into a “QSK circuit” (a device that converts audio tones into key clicks). The QSK circuit is connected to the FT-817’s key jack.

But then I hit a problem. The audio level coming out of a phone’s headphone jack is very low. It was insufficient to trigger the transistor (Q2 in the schematic shown below) in the QSK circuit into conducting. The key jack on the FT-817 presents a DC voltage of 5 volts from an open collector circuit in the radio. When the QSK circuit operates it grounds the key connection in the radio to generate a CW signal.

My innovative gizmo needed a boost which was provided by a simple one transistor amplifier powered by a 9 volt battery. The transistor (Q1 in the schematic shown below) is biased on by a 2.2Kohm resistor and converts the weak signal from the phone to a level that allows the QSK circuit to do its job. It worked. The complete circuit shown in the schematic may not be elegant but it passed the smoke test and does what it was designed to do.

The FT-817’s internal keyer must be turned off for this to work. So what happens when the operator needs to send something that isn’t in the memories? Simple. The phone keyer is paralleled with a set of paddles. When sending a manually keyed transmission just hit the “keyer” button in the FT-817’s menu and use the paddles – or simply use a straight key.

An Audio Filter for the FT-817

My favourite radio for POTA activations is my Yaesu FT-891. I love it because of all the sophisticated IF filtering tools. I also own a Yaesu FT-897 which has pretty darn good “Digital Signal Processing” but it works at audio frequencies (AF) instead of intermediate frequencies (IF). Since the FT-817 has no filtering at all I had to build my own.

I chose K4ICY’s design. You can view his website page at I am sure Mike won’t mind me sharing the schematic here on The circuit is based on a fairly standard op amp design but Mike does an excellent job of describing the operation and construction in great detail. I highly recommend you visit Mike’s website to learn more.

My own version of K4ICY’s CW filter employs a quad op amp chip. The filter is basically a 4-stage filter. Each stage is identical so construction is quite straightforward. I built the filter on a piece of perfboard that fits snugly inside the battery compartment of the FT-817. Of course, the battery holder must first be removed. After much agonizing I cut a small section of the battery cover away to allow the connections to audio in/out and power to be routed out of the case.

The performance of this circuit is stunning. Not only does it act as a very good filter it also serves as a zero beat indicator. When you are tuned in to exactly the same frequency as the station you are monitoring there is a marked increase in audio volume!

Quod Erat Demonstrandum

So I have now eliminated the two principal reasons why I quit QRP and maybe shouldn’t have. Shall I now rejoin the swelling ranks of those who do more with less? Yes, maybe …

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