That's the same Centech brand as the red rectangular cheapies form Harbor Freight.
Pretty much the same functionality.  And I'd guess the same stuff inside.
The primary differences I see is that this ebay job has a continuity beeper  and a backlight. 

Jerry

On the CEC firmware, and the original factory firmware when you use the PTT for SSB the transmit frequency is what is shown on the display. When you key the transmitter with the CW key the firmware changes the transmit frequency to be lower than what is on the display by the same amount as the "sidetone" frequency setting. 

For someone hearing a CW station that they would like to respond to, then, if they tuned the other station at the same tone as the sidetone they hear when transmitting, everything is great. If you were wanting to initiate an exchange at a specific frequency (like inside the lower edge of amateur band) the unexpected offset kind of sucks. 

If the display at least switched to showing the actual transmit frequency, when transmitting CW, at least people would not be kept in the dark about what the radio is doing. Basic user interface feedback. Pretty much people assume the displayed frequency is the frequency they are transmitting on, and this shift from the display is unexpected behavior.

Tom, wb6b

I'm not sure I would recommend trying to replicate all the ACV/DCV/Ohms/Amps/mAmps ranges 
of a $1 Centek DVM from Harbor Freight.
But instead of spending the extra $11 bucks on a DVM with a capacitance range, it might be worth
building this capacitance meter into your Raduino:
    http://wordpress.codewrite.co.uk/pic/2014/01/21/cap-meter-with-arduino-uno/

Select it with a menu option.

Jerry

I'm not sure what you mean about shifting the BFO.
The BFO has nothing to do with transmit.
On receive, it can remain exactly where it was for SSB operation.

And no idea what all the other software releases out there are doing.
Mine is rigged as follows

On transmit the dial shows the frequency of the CW carrier (of course).

On receive (if RIT is not enabled) it still shows the same operating frequency in the LCD.
However, the VFO is tuned up in frequency by however many hertz the cw sidetone is set up to be
if operating in LowerSideBand mode, and down in frequency by that many hertz if UpperSideBand mode.

Since I worked for years with not terribly selective receivers (no crystal filter) I prefer to tune in a CW carrier
by going for a zero beat in the audio.  In this mode, the BFO is moved to the center of the 12mhz
crystal filter passband, halfway between USB and LSB mode.  I call it ZSB. 
Then once tuned in, flip back to LSB or USB mode to operate CW.
This ZSB mode is also handy when calibrating the the 25mhz si5351 reference oscillator as per post 35235.

Jerry, KE7ER

BITX QSO Afternoon/Evening, Sunday, June 17, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Join us as we make contacts with our BitX-40s or uBitXs or anything else on 7.277 MHz in 40 meters!

This is a worldwide event for BitX40 (and other QRP) stations starting at 3PM and 7pm in each time zone. To participate, call CQ BitX on Sunday, starting at 3PM and/or 7PM your local time. The BitX QSO Night continues through the evening and conditions usually improve after sunset, so it is worthwhile to participate later in the evening.

Suggested Best Operating Practices:

Work at QRP power levels unless conditions require more power.
Call and listen for CQ BITX on the hour and every quarter hour.
It is helpful if you call CQ BITX with your callsign, name and location. 
Repeat your callsign a number of times during your CQ BITX and during QSO's.
Start a QSO by confirming the callsign, location, name and signal report of the other operator.
Say the callsign, name and location of the other operator so others can hear.
If the frequency is busy, avoid long conversations.
After your initial QSO is complete, ask if there are any other stations who would like to contact.

Report your QSO's, discuss propagation, noise, signal reports, audio reports, antenna type, etc. in this thread.

This is an undirected, scheduled event.  The BITX QSO Night relies on you to call CQ BITX to initiate contacts with other stations, so warm up that final and transmit a few calls on Sunday evening.  Talk to you then!
--
John - WA2FZW

I'm another fan of the Harbor Freight cheep/free DVM.  I honestly don't know how many I have as they are so cheap and handy I keep them all over the place.  If the zombie apocalypse comes I will stay safe in a shelter made from all my harbor freight tarps lashed together with harbor freight dvm leads while I stab zombies with harbor freight screw drivers.



--
www.bitxmap.com

For most anything you'll do with the ubitx you don't need an expensive
desk meter.

this one:
www.ebay.com/itm/Digital-Voltmeter-Ammeter-Ohmmeter-Multimeter-Volt-AC-DC-Tester-Meter-US-Seller/271496690158?hash=item3f3676b9ee:g:qgUAAOSwHnFVkYPk

is representative of one that has lots of functions. It's a lot like
the one I use much of the time. PLEASE don't hook the test leads up the
way it is shown, it won't work!

There is a huge gap in its current measuring scales, from 200ma to
10amp in one big jump, but that will probably get you by.

tim ab0wr

On Thu, 14 Jun 2018 19:11:08 -0700
"Mark M" <junquemaile@cox.net> wrote:

Sorry if this is a bit off topic but it is related to uBitX hacking...

My ancient, el-cheapo VOMs (Radio Shack/Harbor Freight freebies) all
have pretty much ceased working so I'm looking for some suggestions
about suitable replacement units. I'm not looking for lab quality,
just something for a hobbiest/amateur hardware hacker (like for
modifying the uBitx). I'd like to find something that's reliable and
reasonably accurate for a few 10's of dollars. I see many units on
Amazon for around that but don't know which ones would be good buys.
So, any advice from y'all?

Thanks & 73....     Mark    AA7TA

Do you have an swr meter that shows forward power? Does it flcker when
you speak into the mic?

The mic amp in the ubitx expects to be fed from a high-output electret
mic. Is your Astatic mic an electret mic or a dynamic mic? If it is a
dynamic mic you might have to build a small amp to use with it to get
enough output.

tim ab0wr




On Thu, 14 Jun 2018 18:33:21 -0700
hotrod541@hotmail.com wrote:

I have assembled my uBITX and when I set up the power-amp bias
everything adjust fine until I key the mike and grunt loudly, I don't
see any increase in the bias. I assume that the transmitter is not
working.  I have installed a led for rec. and trans. and it keys
correctly with the led, I get red on trans, green on receiver. I
installed a four (4) pin mike connector and it may not be wired
correctly. It is wired, pin 1 blue (gr), pin 2 orange (ptt), pin 3
purple (mic), pin 4 case ground. I am using  a Astatic CB mike. I
must not have one of the wires connected right but it does key as I
can hear the power supply load increase when I key.  I cannot believe
the receive on this radio, it does a great job just like it is. Any
help would be appreciated. Buddy3223 KJ4ZSI

Michael,

It would actually make the most sense to me if *both* the TX and RX
frequency stayed the same, only the BFO would be shifted. If you are
working CW on 7030 the both the TX and RX should show 7030! If you
change from CWL to CWU only the BFO should move. Otherwise you wind up
continually having to do math in your head to determine what frequency
you are actually listening to!It's far easier and quicker to make the
rig do that!

tim ab0wr

On Thu, 14 Jun 2018 18:19:42 -0700
"Michael Babineau" <mbabineau.ve3wmb@gmail.com> wrote:

I have confirmed the same thing in the CEC firmware V1.08.  The uBITX
display frequency is the RX frequency not the TX frequency.

I will now explain why this is a problem.

This is not theoretical .. I tried this with my Flex-1500 with both
rigs side-by-side, TXing into dummy loads. 

My Flex is transmitting on 7.030 Mhz CWU exactly (dial frequency BTW)
using a 700 Hz RX offset. The uBITX is on CWU has a 700 Hz sidetone
set (ie offset) then the dial on the uBITX needs to be at 7.029.300
Mhz  so that it is receiving a the Flex with a 700hz audio tone. Both
stations can hear each other with a 700 Hz tone. This confirms that
the uBITX dial frequency is the receive frequency not its transmit
frequency.  I can also see and hear that the uBITX is transmitting on
7.030 Mhz with this dial setting.

Now I switch the Flex to CWL without changing frequency. I leave the
uBitx on the same frequency (7.029.300 Mhz) and still on CWU. Both
stations can still hear each other with a 700 Hz tone. Changing modes
on the Flex left the TX (dial) frequency the same and only moved the
RX frequency of the Flex to the other sideband (ie. the Flex RX
frequency switches from 7.029.300 Mhz to 7.030.700 Mhz). 

I put back Flex back on CWU without changing frequency (ie. dial
still shows 7.030 Mhz). Now switch I the uBITX from CWU to CWL. The
dial frequency on the uBITX still shows 7.029.300 Mhz on the dial but
it is now transmitting at 7.028.600 Mhz and is inaudible to the Flex
which is still listening at 7.029.300 Mhz !

With any rig in CW mode, when you have a station tuned in and are
listening you should be able to switch from CWL to CWU at at any time
and without retuning and you should be able to hear the other station
and he should still be able to hear you. The whole idea of switching
sidebands in CW mode is to be to use it as a means of avoiding
adjacent noise. Sometimes switching from CWU to CWL will allow you to
avoid QRM. 

That is only possible if the uBITX TX frequency remains fixed on CW
sideband changes (CWU/CWL) and the RX frequency changes according to
the sideband selected and the configured offset.  

So that means that the display frequency since it is fixed, must be
the TX frequency. The RX frequency should change on switching from
CWU to CWL based on a minus or plus offset from the TX frequency. 

Cheers

Michael VE3WMB

I picked up about a half dozen harbor freight DVM's when they were on sale for $1 or so.
Not auto ranging and pretty easy to blow, but well worth a buck.
Something I can knock around without worrying too much.

If you're willing to spend big money, $12 will get you an autoranging meter that shows capacitance:
I got one of these 5 or more years ago:
    https://www.amazon.com/GigaMax-Multimeter-Pocket-Size-Resistance-Capacitance/dp/B00RSQD6IW
I can't recommend it, as you can see how small the "V" indication is that shows it is reading Volts.
That can do an autoranging jump to "mV" to show millivolts, and it takes me awhile to figure my probe
isn't quite making contact with the battery or whatever.

But do consider getting one with a capacitance range, it's handy.
This UT10A generally shows about 100pf across the leads with my hands on the probes.
I put the cap down on the desk and hold the probes to it, take a reading.
Then gingerly pull the probes away a fraction of an inch, take a second reading.
Subtracting the second from the first I get the value of the cap to within about 10pf.

Jerry

Buddy,

Hope you don't mind, I created a new thread with a descriptive name.
"Need help" just doesn't do it.  
Original thread was   https://groups.io/g/BITX20/message/51984

I suggest you try sending CW into a dummy load.
Finding out whether it works or not will divide the problem roughly in half,
If it works with CW, then everything from Q90 out to the antenna port is fine,
and the problem lies somewhere between the mike and T2.

The fact that the rig receives means that most of the stuff from T7 to T2 is working.

Jerry, KE7ER

Sorry if this is a bit off topic but it is related to uBitX hacking...

My ancient, el-cheapo VOMs (Radio Shack/Harbor Freight freebies) all have pretty much ceased working so I'm looking for some suggestions about suitable replacement units. I'm not looking for lab quality, just something for a hobbiest/amateur hardware hacker (like for modifying the uBitx). I'd like to find something that's reliable and reasonably accurate for a few 10's of dollars. I see many units on Amazon for around that but don't know which ones would be good buys. So, any advice from y'all?

Thanks & 73....     Mark    AA7TA

I have assembled my uBITX and when I set up the power-amp bias everything adjust fine until I key the mike and grunt loudly, I don't see any increase in the bias. I assume that the transmitter is not working.  I have installed a led for rec. and trans. and it keys correctly with the led, I get red on trans, green on receiver. I installed a four (4) pin mike connector and it may not be wired correctly. It is wired, pin 1 blue (gr), pin 2 orange (ptt), pin 3 purple (mic), pin 4 case ground. I am using  a Astatic CB mike. I must not have one of the wires connected right but it does key as I can hear the power supply load increase when I key.  I cannot believe the receive on this radio, it does a great job just like it is. Any help would be appreciated.
Buddy3223
KJ4ZSI

I have confirmed the same thing in the CEC firmware V1.08.  The uBITX display frequency is the RX frequency not the TX frequency.

I will now explain why this is a problem.

This is not theoretical .. I tried this with my Flex-1500 with both rigs side-by-side, TXing into dummy loads. 

My Flex is transmitting on 7.030 Mhz CWU exactly (dial frequency BTW) using a 700 Hz RX offset. The uBITX is on CWU has a 700 Hz sidetone set (ie offset) then
the dial on the uBITX needs to be at 7.029.300 Mhz  so that it is receiving a the Flex with a 700hz audio tone. Both stations can hear each other with a 700 Hz tone. This confirms that the uBITX dial frequency is the receive frequency not its transmit frequency.  I can also see and hear that the uBITX is transmitting on
7.030 Mhz with this dial setting.

Now I switch the Flex to CWL without changing frequency. I leave the uBitx on the same frequency (7.029.300 Mhz) and still on CWU. Both stations can still hear each other with a 700 Hz tone. Changing modes on the Flex left the TX (dial) frequency the same and only moved the RX frequency of the Flex to the other sideband (ie. the Flex RX frequency switches from 7.029.300 Mhz to 7.030.700 Mhz). 

I put back Flex back on CWU without changing frequency (ie. dial still shows 7.030 Mhz). Now switch I the uBITX from CWU to CWL. The dial frequency on 
the uBITX still shows 7.029.300 Mhz on the dial but it is now transmitting at 7.028.600 Mhz and is inaudible to the Flex which is still listening at 7.029.300 Mhz !

With any rig in CW mode, when you have a station tuned in and are listening you should be able to switch from CWL to CWU at at any time and without 
retuning and you should be able to hear the other station and he should still be able to hear you. The whole idea of switching sidebands in CW mode is to
be to use it as a means of avoiding adjacent noise. Sometimes switching from CWU to CWL will allow you to avoid QRM. 

That is only possible if the uBITX TX frequency remains fixed on CW sideband changes (CWU/CWL) and the RX frequency changes according to the sideband selected and the configured offset.  

So that means that the display frequency since it is fixed, must be the TX frequency. The RX frequency should change on switching from CWU to CWL based on a minus or plus offset from the TX frequency. 

Cheers

Michael VE3WMB 

Thanks for the guidance and advice. I tested my rig today and RF gain seems to be working. I'm used RG-316 left from another project. I ran the coax across the bottom of the board to a 3-pin male connector. This makes it easier to keep pulling it apart