Thank you a lot for the input guys!? It seems I should do nothing with the v3 for now until more data is in -- either that or use a spectrum analyzer and strike out into the unknown!? lol.

I happen to have a spectrum analyzer from hell at work, but I've never used it at frequencies as low as the ubitx.? I think I'll hold tight, and tinker with the v4 currently working ...

No, sketch and memory manager together available there

Thanks, Snowist. It seems the 1.11 refers to the Memory Manager and not the uBitX sketch, so I seem to have the latest version 1.10 for the uBitX.

=Vic=

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Hi Curt

You were bang on with this.
I put a DFM onto R110 which is the BFO oscillator and it was 5KHz off the 12MHz

The calibration option when selected offers adjustment, tweaking away improved the sensitivity to more like the 1uV promised.
I'll read the frequency it needs to be set to to give the sensitivity at some stage and do some calculations, I expect that will give me the exact crystal filter response.
The cheapy encoder supplied is not brillant and tuning does jump about. I have a nice Bournes part rescued from a junk sale unit and that improves the tuning nicely, it's 128 step which is far to many steps, but I'll look around for a part with less steps. It's not a concern as that's not my intended use for the BITX.

One calibration option if you are not careful puts the board into transmit which upset the RF signal generator, I did not have 12v on the PA stage so no damage done, but I need to spend some more time reading up on this.

Thanks very much for your advice, I'll settle down and do some more testing before I build the board into it's case.

****

Not sure how interested anybody is in this,
Short history;

I bought a couple of solid state (1980's) HF transceivers from a 4x4 vehicle rally. With PA and Antenna auto tuners. ( I like 'green boxes'!)


It was made in the UK but only sold into Australia as far as I can tell.
The design made extensive use of tantalum capacitors which if they get moisture in can catch fire (I've seen a tiny flame coming out of one)
The internals of the radio, mainly the flat flexi wiring it made extensive use of, were so badly damaged I made a decision to replace the electronics, and the BITX is just perfect size to fit into the existing case, with some room for a controller and antenna filtering / tuning.

I bought the BITX? with the intention of writing code to control the Si part and allow me to use the control panel from the Army Radio which is basically about 20 switches to programme frequencies in, and end up with a working Raven radio.

Again, many thanks for your help,

BobM0RHE

Bob

The 12 MHz crystal filter is quite narrow. If the bfo is way off,? the signal will be highly attenuated by the shape of this filter. Second,? the receiver has less total gsin than some receivers so a good antenna is needed, not just a short piece of wire. My bfo came way off and it wasn't easy to get it aligned. When aligned, big signals will be quite loud in headphones needing the volume control to be set quite low. Weak signals might need near full volume. If you like to use a speaker, you may wish to use an amplified one, there are many inexpensive ones out there. But first important to align the bfo.

Curt

-- 
Bob Head, Rotronics Systems Limited, 01252 722686

--
Best 73
KD8CEC / Ph.D ian lee
kd8cec@...
(my blog)

--
Best 73
KD8CEC / Ph.D ian lee
kd8cec@...
(my blog)

@Vic you can get CEC 1.11 from following Github repo

To run different firmwares on Raduino you don't need to buy additional Raduino. Just get a few more Arduino Nano unsoldered and flash firmware on different Arduinos.
Its so easy removing Arduino modul and replacing new one on the socket.

It looks like my radio is a V.5

I came home tonight to the screeching gone, but now there is nothing.? Just a bit of very low noise even when connected to an antenna.

I clicked "Load Factory Setting" and the following values are set
Master: 6125
USB:?11058000
Configuration attached.?

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That worked, and was exactly what I was looking for!!!

Thank you!

Jerry

Thanks for pointing out better 45 MHz devices as being a help against spurs, but I wonder if biasing them with a bit more current might help. I do have some eclectic vhf npn devices in my stash.

I did install an LC filter, but only in transmit path. Modeling using a Q around 70 per coilcraft catalog conveys enough rejection,? still I am skeptical I might be a little short.

I am getting around 4w on 28 MHz CW so not sure I need a mod per this thread.

73 curt

Thank you very much!

--
Tim Keller - KE2GKB

Evan

I don't expect us all to purchase spectrum analyzers, that we might just use a few times.? I am confident that repeatable solutions will emerge for curing the spurious, that should be good enough for builders that don't have spectrum analyzer access.? Our club members are building 23 units, and eventually we should have data on most if not each of them.??

I think there is evidence around that many ubitx units have spurs on both CW and SSB.? (A table of my spurious are here somewhere).? Others have data clarifying the transmit harmonics relate to leakage within the relays.? Adding a simple small board containing 3 relays to separate the input and output function should be a high success solution - most of our builders plan to use this method (we kitted it for them).? A few may try Axicon relays - it might work depending upon the severity of their spurs.? We found an added xtal filter will cure the mixing spurs, but at least 2 of us have degraded CW output on 40m.??

Curt

In the questionable tests that I have done on my v4 with the RF Explorer and SDRPlay as a Spectrum Analyzer, I have seen that the SSB signals do not have the harmonic issues, but does have the spurs, and vice versa.? The questionable part is the accuracy of the SA results.? I have worked out the audio two tone generator and step attenuater.? I have a personal belief from measuring the clock#2 signal with an oscilloscope that the harmonic content is very high, and that is being fed to the PA stage, before there is a chance to knock it down with the low pass filters.? One of these days I plan to temporarily place a LPF on the clock#2 signal for 8mhz and test the 40 m harmonics.? My guess is that there will not then be an issue.

If the experiment does prove that the harmonics start with the clock#2, then a switched LPF in place of the current fixed LPF between the first mixer and the PA driver may be the only solution to ultimatly solve the issue for CW.

My data also points to a legal SSB rig, as long as you do not overdrive the audio and you put in the 45 mhz LPF to remove the spurs when operating above 20 m.

I have received my v5 board, however I am still not sure of the reliability of the way I am able to measure spectrum content.? A Rigol or Siglent is still a significant investment, and have a lot of convincing of others (my wife) that it is a good use of funds.? I just bought an IC-7300 this year, so not sure I can squeeze it in at this time.? This long explanation is to justify that I will not be able to do a definitive test on the v5 board.? I had also checked at my club and when asked as to what SA that they might have, they all offered the RF Explorer as what they use.

Above are my opinions, based on my observations.? ?Yours may be different.
73
Evan
AC9TU

Great point, Curt -- thank you! I've actually been thinking about adding an external relay filter board anyway.? So far I only use it for cw, so many of the ssb aspects aren't terribly important immediately .??

On my v4 I did a lot of transistor replacements etc and liked the results . Not having a spectrum analyzer I haven't been brave enough to try ssb.??

Brutus

If it were me, I would not covert a v3 to a v5.? I don't recommend replacing over a dozen crystals !??

We don't yet have any data that a v5 has lower overall spurious than v3 or v4.? I hope it should be better but the data so far isn't that encouraging (to me anyway) for the factory board (we honestly need more than one sample. have not seen ssb data).??

I think any ubitx would likely be compliant if relays on an external board were used.? Whether axicom relays solve spurious may depend upon the board.? Respecting that >90% of us don't have a spectrum analyzer, it may be more of a personal choice whether to replace relays or add a relay circuit board.? Either might be compliant or somewhat close.??

Curt