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Over the past week, I've been playing with my 630m transverter summer project.





It's not the normal type of transverter that would produce a signal on 630m (~475kHz) but rather, one that will produce a signal on twice this frequency. My630m amplifier, using switching FETs, was designed and built with a 'divide-by-two' input circuit, to allow for greater frequency resolution when first constructed as a 2200m system. I really don't want to modify the transmitter and prefer just to be able to unplug my DDS and plug-in the transverter, allowing me to run WSPR, JT9 and several other digital modes when needed.

So far I've not been able to get the transverter to produce the desired low voltage 950kHz squarewave output, although I'm closer than when I began the troubleshooting.

My circuit is basically a G3XBM 630m transverter, without the FET final amplifier. Instead, the driver feeds a  full-wave rectifier frequency doubler for 630m, designed and published a few years ago by Jay, W1VD. Although I can get a squarewave end result, I think harmonics creeping into the process earlier down the mixing chain are causing non-symmetry in the output.









I'm using a 3.200MHz crystal oscillator with low level RF drive from my IC756PROIII transceiver at 3.675MHz feeding an ADE-1 double-balanced mixer in order to utilize the 'difference' frequency, 475kHz.

3.2MHz signal out of oscillator buffer stage

475 kHz signal out of mixer stage

Signal out of 'squarer' stage

Signal out of full-wave bridge

Signal out of LPF

Asymmetrical squarewave from 4046 output

I've tried a 3-section LPF with a cutoff of ~600kHz between the mixer output and the next stage, trying to knock down the 'sum' frequency of 6.875MHz and any crystal harmonics but have since replaced this with a 630m diplexer at the mixer output to pass anything below 1MHz to the squarer and anything above 1.5MHz to ground. I'll keep playing with it ... until it works as it should or I have no hair left to pull out. I may also just rebuild the circuit, Manhattan-style, with normal sized parts, making it much easier to change or modify as I need. The scope grabs shown above are with the diplexer in place at the mixer output. It seems like something in the full-wave frequency doubler is amiss. I've looked at T1, the bifilar transformer several times but don't see anything odd but that's the stage where things seem to go south. Maybe it's an impedance matching-thing, something I'm yet uncomfortable with when it comes to properly matching various stages.

I also now realize that the section of transverter I have chosen will require post-mixer filtering, not shown in the schematic. Not using the last stage (FET PA) and its associated filtering, has no doubt caused more harmonics to appear in the output than anticipated. If I redesign and rebuild, I will add an LPF after the crystal oscillator as well as at the RF input port and pay more attention to post-mixer filtering.

Another route to try, rather than the W1VD doubler, may be this 4069 IC doubler or a similar 4011 doubler.

Although the project outcomes have not yet been achieved, the process has been a positive one in a couple of respects and well worth the time spent so far.

I have learned that working with the 1206-sized SMT parts is much easier than suspected and in fact, populating the board with these tiny parts was a lot of fun.  The 1206-sized parts are at the 'large' end of the SMT size-spectrum ... rest assured I won't be going any smaller, at least for now.

My previous taste of SMT-construction was many years ago, when I built a small 40m QRP transceiver using seventy-two SMT parts ... it was an inexpensive kit from one of the QRP clubs. Happily, it worked with no problems but I found the process tiring and laborious and only soldered a few parts on the board each day until it was completed. The present experience was the exact opposite as I found it a very enjoyable experience ... I'm really looking forward to doing more SMT construction in the future.

The other positive outcome was knowing that my PCB design process can work well with the narrower lines, pads and much smaller IC footprints. I still design my boards using MS Paint and have always been happy with the ease at which it works. I know many might scoff at MS Paint but it really is a very versatile little program, with a short learning curve, unlike many of the more sophisticated PCB design programs.

Although I will work with SMT again and, similar to this project, I'll not be concerned about shrinking the board too small, although I'll work towards that goal. My main reason for trying a homebrewed SMT board was to see if I (my eyes) could still handle it and since so many parts are no longer available in the 'normal' size we have been used to for the past several decades ... particularly obvious when trying to source IC's in the good old DIP package. I am seeing a lot of 'obsoletes' pop up for some of my wanted chips, as the larger DIP packages are no longer in as much demand.

And one more positive outcome. I used the project as an excuse to purchase a new soldering station ... one that I had been lusting over for a few years as it is very SMT-friendly compared to my old Weller clunker. It also has an electrically isolated tip, unlike my Weller. The Hakko FX-888D turned out to be everything I had hoped and was no doubt part of the reason that I found the SMT process so enjoyable.

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If you haven't tried building with these smaller components, don't be afraid to test the waters. I have no idea how long our 'normal-sized' leaded parts will be readily available but I now know that their eventual demise won't slow me down when it comes to homebrewing.
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

I went for a quick hike this morning before lunch to some remote farm fields not far from home. I worked France, Serbia, Kansas, Canary Islands and Russia. It was a beautiful, beautiful morning.

I started out on Hunkins Pond Road and hiked north up an old farm lane. Then I turned east on the old range road. This old road cuts straight through the woods for probably 8 miles. But just a short way up this road I came to David Swain’s hay fields on top of the hill. It’s a beautiful place. This view is looking east toward the Belknap Mountain range.

I set up the KX3 at the edge of the field and tossed my wire over a huge maple. I started out on 20 meters. The first station I heard was Bert F6HKA in France. He was working the Romanian DX contest. We exchanged 599s and a serial number. Next I worked a Serbian station YT1A also working the contest.

My third QSO was up the band a little with W0L. Jerry was working the Kansas QSO party and I sent 599 and NH. Then I listened around a bit to see how the other bands were doing. I finally settled on 17 meters where I heard a couple of strong DX stations.

EA8TL in the Canary Islands was calling CQ right at the bottom of the band. Jorge was very strong and we made a quick exchange. Up the band I heard Alex RK3ER also calling CQ. “Hello Jim,” he sent as he gave me a 559. He was 599 to me.

Now the sun was almost overhead and it was getting pretty hot in the field. I packed up and headed home for lunch after a final glance to the south.

Jim Cluett, W1PID, is a regular contributor to AmateurRadio.com and writes from New Hampshire, USA. Contact him at [email protected].

If you want to spark a conversation at your next social event, ask everyone the proper name for this symbol: #. Most North Americans will probably say pound sign or perhaps number sign. It helps to have an international audience, since a person from the UK will likely call it the hash symbol. Lately, the world of Twitter (and other social media) has made extensive use of # to tag keywords, referring to it as the hash mark used to create hashtags. A musician might claim that it is the sharp symbol from musical notation but closer examination reveals that the sharp symbol is quite different.

The AT&T engineers working on the original DTMF system adopted the name Octothorpe for this symbol. There are various explanations and anecdotes that have developed over the years concerning how this happened. Various forms of spelling show up in the literature (octatherp, octothorp, etc.). Doug Kerr’s story is particularly interesting and available on the internet (see below). There are US Patents that use the word “octothorp” to refer to the # symbol. Patent number 3920926 uses “octothorp” for # and “sextile or asterisk” for the * symbol. The term sextile never caught on at all.

For amateur radio usage (North America bias), I hear mostly pound for # and star for *. I suspect that will not change any time soon.

– Bob K0NR

Wikipedia entry for the number sign (#):  http://en.wikipedia.org/wiki/Number_sign

The Symbol on the “Pound” or “Number” Key (#) is Also Called an Octothorpe

The ASCII Character “Octatherp”, by Doug Kerr

The post Don’t Pound My Octothorpe appeared first on The KØNR Radio Site.

Bob Witte, KØNR, is a regular contributor to AmateurRadio.com and writes from Colorado, USA. Contact him at [email protected].

Above is a table that was made for me by Bert PA1B his blog can be found here .Shortly after reading my QRPp WSPR blog post Bert sat down collected my data and made the above table. It shows the calculated lowest possible power in milliwatts. Bert explained to me that the "calculated" lowest power, is the power that could be used (by my dinky antenna setup) to be received with an SNR of -29dB. From the above table it would seem that the 100mW's of power I was using for some contacts could had been considered QRO power! Bert thanks very much for your time and effort and bringing to light the power of QRPp.
Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

Above is a table that was made for me by Bert PA1B his blog can be found here .Shortly after reading my QRPp WSPR blog post Bert sat down collected my data and made the above table. It shows the calculated lowest possible power in milliwatts. Bert explained to me that the "calculated" lowest power, is the power that could be used (by my dinky antenna setup) to be received with an SNR of -29dB. From the above table it would seem that the 100mW's of power I was using for some contacts could had been considered QRO power! Bert thanks very much for your time and effort and bringing to light the power of QRPp.
Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

Above is a table that was made for me by Bert PA1B his blog can be found here .Shortly after reading my QRPp WSPR blog post Bert sat down collected my data and made the above table. It shows the calculated lowest possible power in milliwatts. Bert explained to me that the "calculated" lowest power, is the power that could be used (by my dinky antenna setup) to be received with an SNR of -29dB. From the above table it would seem that the 100mW's of power I was using for some contacts could had been considered QRO power!
Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

  As the long, dog-days of summer begin to come to an end it marks one of my favorite operating activities and that is the Colorado QSO Party.  While I’m not a native to the Centennial State, I am always proud to represent Colorado and this year marks the 140th anniversary of statehood.

The 2016 Colorado QSO Party takes place on  Saturday, 3 September beginning at 0400 UTC (7 AM to 10 PM MDT).  I have a few mid morning commitments which I need to take care of, but KDØBIK should be on the air shortly after the lunch hour. 

Perhaps it is naïve to anticipate better band conditions for next Saturday.  After all…..

But I for one will be giving it a solid effort from the basement ham shack located in grid square DM79np.  I hope to work you in the 2016 Colorado QSO Party. 

Until then…

73 de KDØBIK

P.S.  Episode 71 of the Practical Amateur Radio Podcast will release Saturday, 27 August.  Thank you for listening!

Jerry Taylor, KD0BIK, is a regular contributor to AmateurRadio.com and writes from Colorado, USA. He is the host of the Practical Amateur Radio Podcast. Contact him at [email protected].