Thanks OM Raj!! Will revert after checking!
73

Jerry,

Sorry, I rethought the prior email and it is the 2nd harmonic that is causing the issue.? Somehow it is canceling some of the square wave that should be the 40meter signal.? That is also why the scope is reading 14.448MHz instead of 7.065MHz.? Going back to theory, there should only be odd harmonics for a square wave.

Could this be caused by a 3rd order mixing product?? 3rd harmonic - fundamental would give the second harmonic.? Why only on 40meters?

73
Evan
AC9TU

Jerry,

On thinking about the waveforms, could it be that the 3rd order harmonic on 40meters, being below the 30MHz filter cutoff is causing the issue?

More data, the TP12 readings for 80meters and 40meters:


73
Evan
AC9TU

On Tue, Mar 30, 2021 at 07:53 PM, Jerry Gaffke wrote:

I'm not 100% sure I understand what a "very high low harmonic" is.

Jerry,

Here are three screenshots from my scope:


They are from TP2 of the ?BITX.? The one that is not the correct measured frequency is supposed to be 40meters.? The frequency for 40meters was set at 7.065MHz on the ?BITX.

73
Evan
AC9TU

Hi Evan,

Yes. I see.

I'll check output on SSB and will look out for your findings.

Best,
N

Thanks everyone, sounds good to me. I will replace the regulator and add the dropping resistor both.
?
? ? ? ?Thanks, Mike

Got it, thank you again Evan.?

As it happens, I haven't tinkered much with CW yet, but I anticipate it in the future. Actually, despite having an Extra license, I have never so much as keyed a mic, not even on the local repeaters that I monitor. I am more interested in QRP,, antenna design and signal propagation under different atmospheric conditions. FT8 allows me to study and learn about these things without taking the time to be social. This WILL eventually change, because there are so many genuinely fascinating people to talk to, but for now, SSB, FM and CW are almost too personal. I want to be lost in the various sciences that are associated with amateur radio, not with the sociology, you know? ;)

Evan,

I'm not 100% sure I understand what a "very high low harmonic" is.
Operating a 7mhz, I assume these are 2'd and 3'rd harmonics, so 14 and 21 mhz.
I'd expect that on pretty much all bands at TP1, especially the odd harmonics as we are feeding a square wave.
However, the 30mhz LPF at L1,2,3,4 should take out anything much above 30mhz.

Keep an eye out for anything undesired that is lower than the 2'd harmonic,?
as that stuff is probably getting all the way out to the antenna.
Otherwise, so long as those harmonics are not as strong as the fundamental,
seems it should be ok.

Jerry, KE7ER

Jerry,

I tried putting a 2.2kOhm resistor in parallel with R104 and got the same results.? Evidently, it is not the diode bias that is the issue.

I did note that the waveform at TP1 and TP2 has very high low harmonics on the waveform as opposed to the other bands where there is just some higher-order ripple on the fundimental frequencies.

Will keep looking.
Thanks again.
73
Evan
AC9TU

Skip,

You correct in that there is still heat that needs to be dissipated.? The reason to go to the higher current rated device is that it can handle the higher current without generating as much heat, or can tolerate the higher temperatures.? I did specify that you do need to have a good heatsink on the regulator and that in most cases adding the dropping resistor will solve the supply issue.

73
Evan
AC9TU

Gamaliel,

Your statement is true IF you do not want to get serious with CW.? There are a couple of options that make the ?BITX operate more as most commercial rigs do on CW.? The most significant is that the dial displays the transmit frequency.? The stock will transmit either the sidetone above or below the dial frequency as delivered.

So If you are planning on mostly SSB and only causal CW use, then the stock software is fine.? That is my opinion, others may have a different view.
73
Evan
AC9TU

开云体育

Mike replacing the regulator on the Radunio will not solve the heat problem. The regulator will source at least 1 amp to run everything that needs 5 Volts. The main problem is that if your supply voltage is say 13 volts the regulator is dissipating the heat of the 8 volts times the amps used. I installed a dropping resistor between the 12 volt supply and the regulator to drop the voltage the regulator is seeing and this reduced the heat the regulator is expected to dissipate. Mine runs much cooler now.?

It *seems* - and someone please correct me, in the likely event that I am wrong, bilut it *seems* that the newest stock firmware is quite solid, and has incorporated many of the advantages of the other firmwares. Would it be true to say that, unless one wants to install a Nextion or Teensy or some other significant mod, it is likely best to stick with the stock? Naturally those wanting to roll up their sleeves and tinker should do so, that is what uBitx is about.?

But staying stock, at least until us new folks acclimate, is looking best, I think.

Mike,

I run a 2.8" display on a stock v5 with just an added heatsink to the regulator.? You could go the extra step and add a series resistor to drop the 12+ volts (I am running 13.8) to a lower value.? I would assume a 1 amp draw and you want at least 7 volts to the regulator.? That means you want to drop no more than about 5 volts.? At one amp that is 5ohms and 5watts.? I used 2 3watt 2ohm resistors.? Close enough.

The total power draw on receive is under 400ma, so the above is really worst-case estimates.? The total 5vols is probably under 200ma.? That means you could just add a series resistor to drop the input voltage and dissipate the power in the resistor rather than the regulator using the stock regulator.? So if the max current is 500ma, and the lowest supply to the rig is 10volts, then you can drop 3 volts across the resistor at 500ma = 6ohms at 1.5 watts.? This would also mean that if the supply voltage goes under 10volts the Raduino would start acting erratic.

The true belt and suspenders person would do both: replace the regulator AND install the dropping resistor.? UNLESS you were designing for portable operation THEN a buck/boost regulator might be a better option (with a power line filter on the output).

Lots of options.? Makes my head spin.
73
Evan
AC9TU

Nick,

If you scroll back through some of the earlier posts on this thread you will see that I have a very similar issue with my v6 that I just assembled in the last two weeks.? It is not as drastic as your reduction in power on 40meters, 5watts vs your 3.24watts.? I ran a test using a tone generator as the audio input and got different results.? 40meters was the highest output and then tapered down from there to 10meters being the lowest, as expected.? This points to an issue with unbalancing the mixer to get the clock2 to the power amp as suggested by Jerry KE7ER.? I will try reducing the value of R104 to maybe 1kohm (add a 2.2k in parallel).? I will post what I find out.

You can simulate an audio tone generator by playing a constant tone on a PC or mobile and holding the mic close to the speaker.

The good news is that SSB is not affected.? The bad news is if you wanted full output on CW.? Read the messages from Jerry for more information.? Thank you, Jerry!

73
Evan
AC9TU

Hi Evan,

QRPGuys' Dummy Load/Power Meter kit arrived. Built and attached. Handy piece of kit for QRP power levels. Anyhow, essentially it confirms the reading I received with the borrowed meter ie 18V measured at 7.150MHz meaning 3.24Watts output.

I checked the other bands and they correspond to previously measured levels. 30m gives 29V, equivalent to 8.41Watts, 20m 26.7V = 7.13Watts, 17m, 24V = 5.76Watts, and 80m 35V = 12.25Watts.

I have also built an RF probe but am unsure what to test with it..?

Best,

Nick

Thanks a lot, Bob! /s
Now my wallet is a little lighter than before...

Yes, my V6 has a heat sink on the Raduino with the 7805. It still gets quite warm to the touch.

So you think replacing the one on the Raduino would run both the V6 and the Nextion 5 inch display?

? ?Thanks,? Mike

Justin

Ok L1 0.5mm? 3 turns
L2 to L7 0.8mm

yes 100nf =0.1?f? on the button (s)? --> you have 3 buttons max

On the match tandem, I think to use the wire the big 0.8 mm? or more (1 turn) that go in and out RF. (This is where the power passes)
Do the 10 turns with the 0.5 if there is enough left, or other wire, (I have stock from old transformers)? it does not matter too much (There we recover a part of the power to made? SWR for decoding? FWD and RVS? with the diodes. After the PIC makes to enslavement to find the best compromise SWR with modifing relays postions.

cdt

Gerard -

I also used the appropriate drill bits to wind the air-core coils.

1.? I wound with 3 turns.? The picture I have is a bit fuzzy but it looks like 3TY as well.

2.? All 6 toroids appeared to be identical.? Two sets of two and two singles for the 4 coils.

3.? My kit came with three types of wire.? L2 - L7 were wound with the large enameled wire, L1 wound with the small enameled wire, and the dual/binocular/tandem coil both sides wound with the small insulated wire, 10T on each side.

I read reviews on several kits and found some complained about their kit not having enough wire to wind all of the coils/transformer.

The users manual for the extended board suggests 100 nf which I believe is .1 uf.? I have not installed these yet and so far have not noticed any issues.? I will probably use thru-hole parts at the switches if I do.

Robert - I ordered another kit for my upcoming mobile rig project from a different seller (it had a couple switches the other didn't) so we'll see how it goes.? Both confirmed shipping within on day and both by Ali Express Standard Shipping.

73,

Justin B.
KI5GKD