Ultra Portable Radios.

Started by gil, July 16, 2015, 03:07:29 AM

Previous topic - Next topic

Rescue9

I'm with you Gil on the small size versus small power. I want something that I can take anywhere, hence the prepped part of our forum. As a fire / rescue guy, I very much understand the need for a portable, real-world emergency comm setup. It is one of the reasons that I built the m0nka radio; small package, big possibilities.

Seeing the new KX2 has me drooling though. I simply have to make this part of my EDC bag. Now all I have to do is find the funds... no small task on a city government employee's paycheck.

RadioRay

May 22, 2016, 07:16:03 PM #16 Last Edit: May 22, 2016, 07:17:34 PM by RadioRay
Sure Gil -

Feel free to use them, and maybe they could be used for T-shirts and coffee cups to generate a little income for this site :-)


>Ray

Ps. Right now, I am looking at your former MTR2b and at a small, German tobacco (a) tin and getting ideas for my UPR.

(a) - Reiner Professional.  German made, in a Danish style. 
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

gil

Thanks Ray.

I wish I knew enough or had time to learn radio circuit design. We need a circuit designer on this board! We'd get something cool going and make kits. I'd  start with a single band CW radio with a  20W output but low current draw on receive, regular VFO, a 500Hz filter and the ability to dial down power to save batteries once a contact is made. A bit like a Rock Mite with a VFO and on steroids, with a DFE (direct frequency entry) like on the MTR, what a stroke of genius that was, and no need for a display, which is only useful to go to a sked frequency. But that would imply a DDS VFO, oh well, if Steve Weber can pack a three band rig with DDS and a microprocessor in an Altoids box, anything is possible. And while we're at it, add a Bluetooth chip. I think radio designers all swore a secret oath to ignore Bluetooth..

Gil

vwflyer

QuoteI think radio designers all swore a secret oath to ignore Bluetooth..

Wouldn't a KX2 with bluetooth and a dedicated PSK/RTTY IOS/Android app be the perfect paring? You wouldn't need to use the paddles to send digital and non-CW proficient people could have a portable and easy text entry device.

gil

Definitely. You could also use Bluetooth headphones. Bluetooth paddles would appear, and all kinds of neat things.

Gil

gil

One comment to Wayne: Why go with a proprietary battery pack? A 18650 cell holder would have been much better. I bet that's what's in it anyway. You lose one cell in the pack and the pack is gone.. Especially that the charger doesn't seem to be the balanced type. I'd put a 3x 18650 holder in it and be done with it. Maybe someone will 3d print one, or a holder shell to fit the KX2. 18650s now also come in 3400mAh.

Gil

gil

I am adding one more desired feature for a UPR... I have been looking at the Clansman PRC320.. What a beast of a radio! It sure isn't portable by our QRP standards, but I read a comment from a user who said his tumbled down a hill and fell in a river.. No ill effects! The case sure looks like you could run over it with a truck. So a sturdy case, if not watertight, at least weather resistant is a must. Good thing with kits, you can often choose or replace the case like Ray did with his KX1. Hammond makes great cast aluminum cases.. If I get a KX2, I will surely make a special bullet proof case for it.

Gil

RadioRay

Speaking of UPR's, I just received my MTR5b and WHAT a receiver!  I put it on the air on the home brew magnetic loop and right away K1A / Special Event Station in Texas for Memorial Day came back and about blew my phones off. When I told him 2 Watts - we was astounded.  Great propagation - to be sure. All this on a cheap RadioShack 9 volt battery.

I am already planning an "UpArmored" MTR5b in a waterproof case, much like my KX-1 was http://radiopreppers.com/index.php?topic=897.0, but smaller, due to the relative size of the MTR. Rather than aluminum, I may use the 3D printer at work to make the faceplate to slide into the kayaker case - to maintain water seal.

73 de RadioRay ..._ ._  /shirtpocket portable

Ps. If ONLY Steve had designed in the general coverage receiver - it would have been perfect for a Morse-o-holic like myself, and many others.
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

Wayne

Quote from: gil on May 26, 2016, 03:47:18 AM
One comment to Wayne: Why go with a proprietary battery pack? A 18650 cell holder would have been much better. I bet that's what's in it anyway. You lose one cell in the pack and the pack is gone.. Especially that the charger doesn't seem to be the balanced type. I'd put a 3x 18650 holder in it and be done with it. Maybe someone will 3d print one, or a holder shell to fit the KX2. 18650s now also come in 3400mAh.

Gil

Hi Gil,

Good questions. Nice to see that the folks on this list have put in some serious thought on the topic -- as have we.

First, battery sockets take much more space than the batteries themselves; they're something like 120% of cell volume for a high-quality multi-cell holder, larger in all three dimensions. Worse: they're often unreliable at the high currents available from 18650 cells. The KX2 can draw over 2 amps in transmit mode, worst case, such as when pumping 10 watts into an ad-hoc field antenna that presents a very low-Z load. Even very high-quality holders have contacts that can migrate or distort under heating.

But we also didn't want to leave any aspect of our internal battery pack to chance. The cells we're using are 2.6 Ah and have an excellent track record (millions shipped by the manufacturer). They're double shrink-wrapped, and we had them use a serious, 5-amp plug, unlike some of the poor-quality 0.5 amp plugs you see on other packs. Inside the shrink-wrap is a circuit board that protects the individual cells against over-current, over-temp, and over- or under-voltage.

We also monitor all of these parameters in the KX2's firmware. For example, if temperature or current or SWR is too high, we roll back to a safer power level and stay there. If that doesn't restore target levels, we'll go so far as to exit transmit mode or even shut the unit off. It's all about ensuring safe, reliable operation for field ops. The user should correct the problem (say, by adjusting the antenna or swapping in a fresh battery). Only then can they increase the power setting again.

The matching charger was also carefully vetted. We've been using the batteries and chargers in-house since October of last year, just to be sure. Then we signed up half a dozen top-flight SOTA operators as field testers. They've been using the radios, batteries and chargers daily for over two months. Not a single issue.

One bit of trivia: We designed a custom nylon pull-loop to make it easy to unplug the battery pack's 2.1-mm barrel connector when the pack is inside the radio. The geometry is a bit tight.

Of course you can also plug in the pack externally. In fact you can have both internal and external batteries plugged in at the same time, and the radio will run from whichever has the higher voltage. Inside/outside connectors are diode isolated from each other with low-drop (0.1 V) battery-ORing diodes that were designed for this application. More important, this protects the battery from accidental charge by an unknown power source. (The pack must be charged externally, but this isn't a big deal, as it can be removed/installed in seconds.)

Wayne

gil

May 27, 2016, 07:07:26 PM #24 Last Edit: May 27, 2016, 07:13:51 PM by gil
Thanks Wayne. Good call on using protected cells, which I guess is a simple solution to charging three cells in serie. I am using rechargeable AA cells right now but thinking of 18650s for a bit more capacity. I can charge them with a solar panel having a couple USB outputs and chargers like the XTAR or Nitecore. I will use protected cells as well, but in a holder. Less of an issue with an external supply.

I have used small LIPO packs in the past but I lost them all to bad cells when I inadvertently let them get too low. I suspect the small current draw sort of artificially kept the voltage higher than it would have been otherwise under a decent load, but still depleting the cells beyond recovery. Protected cells would have avoided the issue.

I have put the KX2 on my list of "wants." Worried about being charged VAT here in France. So it probably would have to wait. I'll have to rely on my MTR for camping this summer. I also want a RT-320, totally different animal.

I built a K1 and a K2, bought a KX3, and they were the best radios I have ever used. My only gripe with them has always been the lack of weather sealing. Nothing a Pelican case can't solve, but operating in bad weather is a no-no. No HF radio I know of offers that of course, but one can always dream.

I hope Elecraft is not leaving the kit market entirely.. I know, the K1, K2 and KX1 are still available, and I hope for a long time.

As long as I have you here, here is my issue with current QRP kits, of any make: They are either mostly CW rigs or SSB, and only a few of those like the Weber Suvivor, Iler or OzQRP. The SSB ones however either do not have CW or do as an afterthought, with no keyer or narrow filtering. I want a real CW radio kit that does SSB as well. A dual bander  would be awesome, or even a single bander. A single bander would sell like hot cakes because people are going to want more than one.. Anyway, I like throwing ideas around..

Congratulations on the new baby, it looks like a winner!

Gil

gil

Darn it... I'm so broke now, it's not even funny. I have a KX2 on order...

Gil.

RadioRay

There is the " 1 Watter" which is gaining popularity.

URL:   http://www.kitsandparts.com/1watter-V3.php


Looks like fun!


de Ray  ..._ ._
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

gil

Thanks Ray, that's a great kit for less than $50! Not as small as a Rock-Mite, but frequency-agile..

Gil

RadioRay

That's my thought: a frequency agile RockMite !
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

gil

A frequency agile Rock-Mite with selectable 5-25W power.. Maybe the SW series circuit could be a starting point..

Gil