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Author Topic: all-band transceiver, CW-only  (Read 1017 times)

AC7A

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  • Posts: 7
Re: all-band transceiver, CW-only
« Reply #15 on: November 09, 2021, 07:56:33 AM »

I have constructed a number of QRP transceiver kits that cover 40/30/20. The K2 is my favorite, but it is a bit large and runs about 300 mA receive current. That probably excludes it from consideration unless you are operating portable from a park bench where those factors are less of a consideration.

Next in terms of portability and performance is the K1. It is considerably smaller than the K2 and runs tens of milliamperes of receive current. It is a very clean sounding CW radio and I have used mine for QRP sprints and ARRL Field Days. Mine has the built-in ATU which is very convenient. My K1 performs flawlessly and is a pleasure to operate.

Moving smaller, I have a KX1 that covers 40/30/20. It truly is of a size suitable for backpacking trips. The receiver is similar to the K1, and it has an adjustable IF bandwidth allowing adjustment for everything from SSB to narrow CW. I find the audio output is affected by the headphone sensitivity and a high SPL headphone is needed if you want good volume. I made the 5 Watt mod to mine and it has the internal ATU. I am getting mine packed for a trip next week where I will be operating /5 from OK. It packs nicely with all the bits and pieces in my carry-on luggage.

Lastly, I have an ATS-4 that I assembled over a decade ago. It is very small in size and functions well. It is a bit unconventional in that the tuning is done with up/down tuning switches. The audio does not have the fidelity of the other radios I mention, but it is completely suitable for the purpose. It doesn't have an ATU built in so I usually have to use an external tuner if the antenna is not resonant.

Even though all of the mentioned radios are out of production I find that when someone is looking for one of them posting a Want Ad on eHam, or a QRP list usually brings up someone who is willing to part with one of the radios. Some folks just like to assemble a radio and then after some use it just mostly sits collecting dust. After some years of it sitting on a closet shelf, or on a bench they are willing to part with it.

That might be worth a try.

'73, ac7a
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AE5X

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  • Posts: 1755
Re: all-band transceiver, CW-only
« Reply #16 on: November 11, 2021, 06:34:01 AM »

An SW-3C is now available - same price but different form factor than the SW-3B:
https://www.venus-itech.com/product/sw-3c/
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KL7CW

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Re: all-band transceiver, CW-only
« Reply #17 on: November 11, 2021, 10:39:45 AM »

I have a KX1 and a KX2, both are great.  However, for serious hiking and backpacking the extra weight of the KX2 may be significant.  For a short activation that may not be a problem, but to me the power consumption especially on RX is an issue.  With my KX1 I can operate for approximately 20 to 30 hours on the internal lithium batteries since I do lots of listening and I believe the current drain is less than 50 milliamps. But the one to two watts of power may not be enough for some folks, so the KX2 and other rigs with perhaps 5 or 10 watts of power may be a better solution. In the future I will choose whichever rig works best for a particular activity.  The variable BW filter on the KX1 works "OK" but has its limitations.  When set to a BW of about 700 Hz there is a nice peak in the signal at about 600 Hz, but strong signals on the opposite side of zero can sometimes be heard.  Not a problem for me.  Narrowing the filter further shifts the resonant frequency some, sometimes the result is not what one would suspect.  Works OK at wider BW for casual shortwave BC stations and SSB.  Never had a problem operating from many locations in the US and Europe with overload, but mostly operated with compromise antennas in remote areas. I consider the KX1 filter "satisfactory" for portable operation, and even some from the home station in my rural QTH.  I even built a 15 meter rig and duplicated the same variable 3 crystal filter for my CW operation.  I am a confirmed 99% CW operator for 67 years, but must admit that I have enjoyed a few SSB QSO's on my new KX2 on 17 meters.
                  Rick  KL7CW
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