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Hi there,

I'm waiting for my Ubitx to be shipped and my project is to make a small go box to be portable with no risk of breaking something on the move.

I create this topic because I'll post updates on this project to share and to give ideas for others.

The goal of this box is :

• to be not so big to be carriable easily in a backpak
• to have it's own energy to last about a day
• to be also ergonomic and fun to use in the QRA (so, I'll keep some comfortable knobs)
• to have a connection for a RTL SDR when used at the QRA
• to be installed in a cookie metal box or something similar, but with no holes at all in the box (so you need to open the cap to use the radio, like SOTA boxes for example)
• if possible and if it's not to big, to be able to carry also small materials like earplugs, mic, notebook + pencil, etc.
• with an internal speaker which can be switched on or off to be able to share the contacts with my family or friend
• with USB panel connector to connect CAT on computer a clean way

I'll use this radio at the QRA, but also for SOTA or SOTA like activations (on hills around my QRA for example) and when moving for work (that I do often) to use in hotel rooms for examples.

Box

• it's cheap
• it can be small (or you can find lot of different sizes at the supermarket)
• it's lightweight
• you can eat the cookies inside before ;-)
• it's open source friendly, to keep the philosophy of the global project
• it can be watertight quite easily (if there are no holes, you can use electrician tape all around the cap to have it protected from water)
• with a metal box, you can shield the whole radio

I've in first thought thinked about a Pelicase or something like that. It's so? badass and look like terrific ! But the main problem is the size of the global case (could be difficult to fit in a bag for a 25x25cm box), heavy (beetween 800g and 1200g for the size I speak about) and could be quite expensive.

I've laying around a very nice cookie box which is about 230x230x50mm inside. I think everything should fit and the box is really not to big to fit inside my backpak I use all the time.

Battery

I've some experience with 18650 lithium cells (I've already built several e bikes with lot of them). It's quite cheap, very reliable, and easy to solder (with a point to point soldering unit that I've built).
Also, you can configure the battery pack shape as you to fit in tiny spaces.

As the ubitx is about 10W output, I think the global power should not exceed 20W when transmitting.

I'll make a 3S battery pack (3x 4.2V fully charged, so 12.6V), and I've ordered 3300 mAh cells. I'm thinking about making a 3S4P battery pack, so the capacity will be 13200 mAh.

It will give about 8 hours of transmitting time with that very simple calculations. It could be maybe a bit overkill but with that you can last a whole WE if needed. Also, you don't have to check everytime before you go if the battery is still OK.

Mics and speakers

As the idea is to have something to use at the QRA as my main rig, and also as a go box, it needs to be quite versatile on the things you can connect.

At the QRA

• I'll often use I think a CB mic with a 6 pins connector with the PTT, so the rig should have a 6 pins CB socket
• As I won't have some weight limitations, I'll use an aircraft headset I already have, with 6.35mm and 5.23mm jacks. I'll certainly use adapters to fit the 3.5mm standard jack sockets to avoid overloading the panel with too much sorts of sockets. That kind of headset should give a good audio quality for the ears
• If I use the mic of the headset instead of the CB mic, I'll also need a PTT button directly on the panel to transmit

When moving

• I'll also have the 2x 3.5mm jacks on the panel, to connect maybe a very light and small mic made from the supplied electret mic of the kit and not having to carry the CB mic if it can't fit inside the box (I don't really want to choose a bigger box just to carry that mic)
• The internal speaker could be used outside (I've salvaged a 8ohms 5W something like 60x60mm speaker from an old CB radio)
• Or I can connect earplugs on the 3.5mm jack and switch the internal speaker of if needed

Antenna

The main panel will have a PL259 socket to install all sort of cables or antenna.

At the QRA

I'll certainly use an endfed antenna system, connected with a coax cable like the QRPguys end fed system which is simple :?

When moving

• I've ordered a Watson ATX Walkabout MK2 which should give me (even it's not the best efficiency) a simple way to connect directly the antenna on the PL259 socket and have it attached to the rig
• maybe a small tuner for wire antenna like this one if I can deploy wire antenna :?

So, what do you think about that ? It's not easy and also not a good idea to think about making a "do everything" rig, it's matter of compromise.

I think with this setup it will be still quite carriable and also fun to use at the QRA.

Stay tuned for the next part : the CAD design to fit everything in the box !

I've made some spreadsheet work upon the battery size.

It appears, with 15W global power drained from the setup when transmitting, that a 3S2P should be enough and smaller to fit in the box (and also lighter).

Here is the screenshot :



So, more than 4 hours just on transmit is not bad at all !
If anybody have already measured the real power drain if the ubitx when transmitting (not the output power, the power used on the power supply).
Thx

I've shared the Dropbox folder of this project. So, this way, if you want to download CAD files, BOM, etc, you can !



Please be aware that it's a work in progress project and for now it's just the beginning !

I am currently traveling for work, so cannot take the measurements.? From my memory, I believe that the total power on transmit (CW) was approximately 1.9 amps at 13.8 vdc = 26.2 watts. SSB would vary based on the audio.? Regardless, I believe that the 15 watt estimate is low.? I would use 25 watts.? This can be adjusted by the setting of RV1, transmitter drive.?

Also from memory, there was a lot of worry back when the group was working on smoothing the power across the bands that the efficiency of the transmitter was on the order of 40%, relatively low.? Assuming the 10 watt output, 40% would be at least 25 watts in.? This also coincides with the current measurements from memory.

Am getting old, so memory might be faulty.? Would suggest someone actually measure their rig for validation.

73
Evan
AC9TU

Thanks Evan for such good informations.

I've asked?woody KZ4AK to take some measurements as he proposes to do some. We'll see. Anyway, I've adjusted the spreadsheet you can access on Dropbox, and the transmit time will be now about 2.66 hours with the same battery pack, maybe a bit low for a WE without recharging for example.

Let's confirm that and then I'll make the good compromise upon the batterie size.

73
Adrien F4IJA

Bob?WB8BEL sent me an email with its setup. He allowed me to post it here.

Hi Bob,

Thanks a lot for this share. It's very interesting !

I've received your answer as a private email. Do you mind if I post it on the thread for other hams to read it ?

Thx and 73

Adrien F4IJA

Some news on design :

Global plate

Even I don't really know the cookie box I'll select, I've started to try to fit everything in so tiny space.


Here is the plate with not everything yet, but we can see the global fitting. It's the bottom view. The idea is to have everything attached on this single plate so it's very easy to unmount for the cookie box to diagnostic things or add new things.
The plate is in yellow and will be machined (as I've built a big CNC router for my own company).
The red thing will be an extra heatsink (it's barely a piece of aluminium which will be screwed on the actual heatsinks). I hope, as the setup won't have fans for now, that will be passively cooldown the amplifier.

Amplified mic

After reading lot of things on the group, I'll finally don't use my CB mic, which need to add a proper socket in the case. Instead of that, I'll make a very simple but I guess OK amplified mic based on a MAX9814 chip I've ordered on Aliexpress.

The main problem is to power the amp. I've the idea to power it with a 18650 cell (4.2V fully charged, 3.7V nominal) directly in the mic.

In fact, the cell holder will make lot of the mic itself, I'll just need to print 2 3d printed parts to fit everything. As I want the global thing to be very simple, it won't be cased, so wires will be visible.


I also plan to use the shipped switch for the PTT.
If after I want to case it, I think it will be quite easy though.

Hello Adrien,

Regarding the Mic preamp I would consider the SSM2167 based module rather than the MAX9814 as based on my usage of both the MAX is more of an ALC type rather than compressor type as is the SSM based module.?

I get good on-air reports with the SSM2167 module and the average power is close to double the bare board.

Be mindful of the spurs issues with over driven Mic input (may be less of an issue with the V5 boards). A trim pot on the output of the module is a good idea.

73, John

Thank you John for this information. I've found that the Max is quite easier to install as you do not need extra components.?

I think I'll try it as it's already ordered :-)?

Nice use of the design tools! ?Keep the group apprised of your progress.

I'm looking to put together something that looks kind of like one of those WWII spy radios. ?The Ubitx is about the right size to fit in the size of one of those radios but will be so much more capable! ?Definitely planning on having a battery on board and room for microphone, earphones and key. Not sure if I will have a speaker. ?An HT speaker mic would do the job of both and, maybe, work as a key, too, like is possible with an 817. I'm not much of a CW guy so that might be fine. So many possibilities!

73

Jeff
--
Jeff, K7AIL ?CN87

raoul@...

Yes, keep tuned Jeff ! I'll receive all the parts in a month or so, but I've the time to design well everything to avoid losing time on the build.

Also, all the designs are made with SpaceClaim, that I use everyday in my company.

At the end of the project, I'll be able to put in the folder the STEP file of the design so that everyone should be able to process it.

Salut Olivier,

Thank you for those informations (frenchies talking to each other in english, is kinda fun !)

So, that's quite interesting the running time you have. With that information, I think I should go for example with 3S2P to have extended autonomy, but 3S4P seems to be really overkill, even if you plan to go for 1 week SOTA without recharging, which will ne be my case (just one day session most, maximum a WE with other activities than radio too).

Another question : what do you think about the Nextion LCD ? In fact I'm thinking beetween two things :

• Staying with the LCD 16x02 which is very simple, low current usage, and very basic (I'll add the Smeter mod from KD8CEC?
• Go for a 2.8" Nextion like you, because it's tiny enough to fit anyway

My point is what are the benefits of the Nextion LCD, beside the comfort of use and ergonomy of menus. Also it's fancy and cool with that display ! Does it have other things you can't do with the basic LCD ?

OK Thx Olivier,?

I don't think I'll want to use for now the spectrum nor the CW decode (I'm currently learning hard CW as I 'm a new ham and I hop to be ear ready in about a year!)

So I' ll continue on the standard 16x02 for now.?

Anglais aussi, peut-être? (Fran?ais de lycée, 50 ans passé) :)

73 de ZL2DEX

Dexter that was jus a remark of Olivier. He thinks the Nextion is very convinient to use and that I should consider it in my setup.?

For now I will stick with the stock LCD and will change it if I feel the need :-)

73 de F4IJA?

Hi everyone !

Here is the V1 of the front end plate :