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I have been looking at the schematics of the ubitx and sbitx units.
Both appear to use the IRF510, at least in the diagrams that I found. The sbitx is advertised as 20 watts and the ubitx is advertised as 10 watts. Are they using different versions of the same unit, or just a better design and heat sink?

What am I missing??

Scotty

Topographically they are very similar.?
Its small design differences.

Things like lower output load resistance output transformer turns ratio,
construction,?and increased Drive to meet the need.

Heat sinking is also critical, as are things like lead lengths and mechanical layout
are also factors.

I've seen uBitx deliver over 15W when the drivers were up to the task.

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Allison
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Please use the forum, offline and private will go to bit bucket.

Thank you for the reply. I have been doing some research into these radios for a possible purchase. I am leaning toward the sbitx at the present.? As a past Radio Shack repair tech, I am very familiar with service of electronics. If I do purchase one of these, I am hoping repair will never be needed. But the fact that the schematics are available and a very straightforward design make them very appealing, compared to many other radios I have found. They seem to be very easily modifiable for any new things I might wish to add. My biggest challenge will be to learn the coding to modify software to implement any modifications! If I get one, I will want to make a battery pack and perhaps an antenna tuner for camping or even while sitting in the front yard supervising grandchildren. It seems a better choice than playing games on a cell phone.

Scotty

Hi Scotty,

I own six uBitx and two sbitx.? The uBitx, as delivered, can do SSB, and with a PC and sound card, it can do digital modes.? It is marginal for CW as it does not have a narrow audio filter.? The significant advantage is the lower cost.? It also has a lower learning curve to modify the software that controls the radio.? It is a mature design, as few new mods have been posted recently.? Older mods are becoming unavailable.

The sbitx is good at CW, SSB, and can do digital modes with the internal Raspberry Pi.? It has a steeper software learning curve as it is a software-defined radio.? It is early in the maturity cycle, as updates are almost monthly and are free.? It will get even better and should cost nothing for the improvements.

The actual cost difference will depend on how you want to use it.? As a portable SSB rig, the uBitx wins on cost.? As a digital rig, the sbitx wins.? I recommend the sbitx, as the functionality improvements are just starting, and most are free software based features.? You will be purchasing or building hardware to add functions to the uBitx.? I am in the process of adding functionality to a uBitx to make it CW-worthy, as well as adding AGC, S-Meter, and taming the power curve vs frequency.? The parts cost $100 unless you have an extensive parts/junk bin.

I recommend the sbitx.

My opinion, others may differ, and YMMV
73
Evan
AC9TU

Hi Evan,

I really do appreciate the advice and reasons that you have stated. Since I really like rtty/bpsk style modes as well as cw, I will most likely go for the sbitx model. Also, if modification is needed to bring the ubitx up to what I want, then I am best to start out with the sbitx. I do enjoy ssb from time to time too though. When on a limited radio equipment budget, planning is needed. Not sure of the portable antenna yet, but it will most likely be no larger than a 20 meter inverted vee so that it will fit in a camp site with our pull behind camper at state parks. I might try making it multiband with a tuner and twin lead cable.
Many thanks, 73

Scotty

Hi Roy,
Do you have a link that I can look at that you recommend for making one of those? What bands are you able to use it on without a tuner?

73, Scotty

I chose the simplest antenna. This is a top-fed loop antenna with a total cable length of 43.8 meters.
I made a triangle out of it. Its upper point is at 10 meters (it is a telescopic mast), and the two lower points are at 5 meters.
The fixing of the lower two points is about 3 meters from the high support, so it became an inclined vertical antenna.
If you look at my LOG, you can see that it works quite well. Low swr on 7, 14, 21 MHz. The lowest 14 there is 1.1.
Power for sBitx is RG8X on coax.

At the top point, two baluns are tied in a row. One will match the impedance from 2 to 1 because the loop is around 112 Ohms.
And the other is current balun 1:1 Both are on FT240-43 core. There is a French seller who makes one (eBay), I have a similar one.
Since it is a closed loop, the noise of the antenna is low.
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Gyula HA3HZ