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Beta firmware of KX2 for more battery time at 10W

73 Chris

4 Likes

This is the link to the firmware Firmware & Software – Elecraft and for the beta 3.02 https://ftp.elecraft.com/KX2/firmware/beta/
73 Chris

1 Like

Improvement (unfortunately) only usable by cw enthusiasts
https://www.mail-archive.com/elecraft@mailman.qth.net/msg252745.html

Yet another reason to learn the code and join us :smile:

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Nice… So is this a single byte change in the firmware then (threshold voltage)? :joy:

It’s great that they changed it – but ever since putting the following 3.5 Ah battery in my KX2 instead of the original KXBT2 (2.6 Ah), I’ve never seen it drop down to 5 W anyway, even after 2-3 hours of operation in winter:

Same dimensions, simply add a barrel plug. YMMV!

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Hello,
If I’m not wrong a similar Beta firmware with the Voltage drop cutoff reduction has been uploaded also in Elecraft’s web page for the KX-3.

73 Ignacio

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You have to know that with the same output, the generation of a low-intermodulation SSB signal without splatter in the adjacent channel requires a higher operating voltage than a single-tone cw signal.

73 Chris

3 Likes

If you are ordering in Austria, you will need to go to:

      73 de OE6FEG
             Matt

In Germany you get here made by Samsung

and by Ansmnn

73 Chris

Hi Chris, those seem to be the 2.6mAh versions, rather than the 3.5mAh one. They are also a lot cheaper. Yes, I really did just pay €90 for a battery. According to other posts on the reflector, you can make your own fairly easily. In fact, with care, you could probably reuse the BMS out of the original pack and add in some higher capacity cells. A DIY spotwelder can be rigged up with a large PTM switch, a solenoid from a car starter and an SLAB.
73 de OE6FEG
Matt

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Hi Matt, I noticed that too. I personally built the pack myself with 3000mAh cells. With care I was able to solder the balancer with bms to the classic cells without a solder lug. Not recommended for imitation.
73 Chris

It might be worth other hams trying to persuade their local club to get a cheap spot welder kit.

Unfortunately, the meaning of (unfortunately) was misunderstood. :upside_down_face:

This was written from the perspective of an amateur radio enthusiast who works exclusively in CW mode, with an eye on those colleagues who have not (yet) learned CW.

So don’t worry, there is no related gap in my subject-specific knowledge that needs to be filled… :wink:

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Shack. CW is the secret weapon of the successful SOTAteer.

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Same experience as me. I noticed Rapid Online in the UK were selling off the Ansmann 2447-3031-20 for £30 last summer. This was a slightly older version spec’d as 3500mAh / 37.8Wh. I studied the specs of the cells vs older 18650 cells at 2A load using

https://lygte-info.dk/review/batteries2012/Common18650comparator.php

Modern INR cells have a flatter discharge and higher voltage under load, in my case it indicated that 2A load voltage for the new pack would be 0.6V higher at half capacity vs my old Ansmann pack. Normally you can get the cell type used in a pack from the data sheet.

So its not just the total capacity of the pack, its much higher voltage under typical TX load.

First time I used the new pack was activations of GM/WS-034 + GM/WS-048 + GM/WS-082 in a day, total of 160 CW qso’s and it was still giving 10w at the end. I was impressed so I purchased second identical pack which was still on special offer.

IMO its not really worth trying to build your own packs, but there are much better packs available off the shelf vs the KXBT2

73 Gavin
GM0GAV

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I just built one Gavin. Mainly because this thread wasn’t in existance a couple of weeks ago!

I’m really pleased with it. 58 QSO’s 10w SSB all the way and that was with a -6°C summit temperature on Conachcraig GM/ES-019 this morning.

I fitted balance charge leads to my build.

1 Like

On a related note, I hope that the “KXIBC2” internal battery charger option that the beta firmware release notes hint at is made available soon! Would be great not having to take out the battery to recharge it anymore…

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With so much interest from the now very large KX2 community, the price will probably be “reasonable”, why shouldn’t it? :wink:
https://elecraft-kx.groups.io/g/main/message/70981

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Of course Heinz, it will seem “Reasonable” after 5 beers! N6KR gave some info last year

https://elecraft-kx.groups.io/g/main/message/70239
and
https://elecraft-kx.groups.io/g/main/message/70271

It appears to replace the KXIO2 inc RTC, also the KXBC2 is no longer needed as you charge from regular 13.8v external power source. So a fair estimate of the cost will be KXIO2 + KXBC2 + 25% :rofl:

73 Gavin
GM0GAV

2 Likes

Folks, how do you charge those ready to use battery packs? I assume that balancing circuit is built in, so the only thing I need is 12.6V power source delivering 0.5C