I have been using my V3 uB on CW only and have it working very well. ?But, I have never even heard another one on CW, let alone worked one. ?Is anyone else CW active with theirs?

73,

Tom ?W1EAT

And so many of them!
Don’t like one? Adopt another!

Hi,

During a QSO with a Swedish ham (with both of us at our homes) he told me he had a QSO with a U.S. ham in Oklahoma from Sweden on SSB using 15 meters and 200 milliwatts! So much for large Varian tubes being required for DX. I was using 2 watts and he was using 3.

73,

Bill KU8H

Michigan QRP Club

--
bark less - wag more

If you get a 57 with an IC-7851 it is the absolutely normality to receive a 55 report with the Ubitx from the same station. You get what you pay hihi...

开云体育

Wow! ? Thanks for the report! ?

开云体育

Fascinating programmable attenuators! ?Thank you guys for the education. ?

Got my first european? phone contact on my ubitx yesterday.

It was on 20 meters to a ham in Scotland. It was just a quick call sign and signal report exchange. We are deep in the heart of the USA.
I was running a wire dipole? about 45 feet up.?

I have had lots of contacts in the past internationally on FT8? but this is the furthest on phone with this machine.?
I log on QRZ.?

Overheard on ham say on the air that you need a amp to do phone dx. Ah OK I got a 55 signal report?

Have heard that there a CME has hit earth over night so maybe things will be different today.
73
Dave
K0mbt

Another thought, rather than try to raise the harmonics to match the fundamental, with the likely overload issue. Maybe, I could lower the gain after I measure a harmonic so the fundamental will match the harmonics. Avoiding overload, but pushing measurements more in the direction of the noise floor of the dongle. Again, just have to try it to see what works best. Nice thing about using a computer to drive this thing it does not have to follow a linear sweep sequence, it can jump around and play with the attenuator. And do some other math to remove the images, mirrored around 14Mhz, if I use the "direct" mode of the dongle.?

Tom, wb6b

That is a good price. The chip is an "obsolete" chip, but does not matter. Only 0.5 DB steps, but that is more than needed.?

With my Google Translate App, with some humorous variations in the translation, I can read the label.?

So, yes, maybe I'll give my eyesight a break.

Tom, wb6b

Hi Gordon,

Glad you are feeling better. I'm looking forward to your results.

On a side note, I don't have a second quality receiver to use so I'm going to try to see if I can concoct a spectrum analyzer from a RTL-SDR dongle. I have no idea how accurate any purported DB levels from any dongle/SDR software will be, so I've been looking around for a step attenuator to buy or build.?

I ran across these amazing (and inexpensive) things.??don't know if they may be of any help to you making your measurements. Ordered a couple from Digi-key and they came in a few days.?

In my case I'm going to use two of them (plus an voltage divider like you described) to get a 60+ DB adjustable attenuation range to attempt to calibrate my dongle/SDR and to step the attenuation back down to match the fundamental to get more accurate harmonic measurements. I may need a microscope to solder wires to them, dead bug style. The big issue that will likely need a solution will be the dongle, unlike a ?good receiver, will likely overload on fundamental when I reduce then attenuation to measure the harmonics. Won't know until I try.

Tom, wb6b

Tom

When you measure VSWR you are measuring reflected power. The less reflected power, the lower the indicated VSWR. When you measure a transformer (or attenuator, or feedline, or any circuit element) with 100% loss, there is no measured reflected power. All of the forward power is absorbed by the circuit element and none is reflected. A VSWR bridge sees no reflected power and reports VSWR = 1:1.

WA8TOD

While I agree the only way to measure the effectiveness of a transformer (either an antenna "matching" transformer or the transformer used to couple the output of the transmitter PA to the antenna load) is to measure the power in vs power out. Either by coupling two back to back, or simply measuring the RF voltage on the input (with a carefully calibrated 50 ohm input impedance driving the transformer [transmitters do not magically have 50 ohm output impedances. A 90% efficient transmitter will have a very low, maybe a few ohms, output impedance, for example]) vs the output with the intended load impedance and calculating the power in and out. Also in both the case of antenna and PA transformers, the power level and reactance of the load will be a factor; putting outer limits on how high the SWR can be and power handling. Transmitters successfully use transformers all the time, so I imagine antennas can also.?

However, why would a transformer with 100% loss have an SWR of 1:1. Why would a transformer with 100% loss end up with an impedance of 50 ohms, rather than some other value, like 100 ohms, 500 ohms, 10 or 20 ohms?

Tom, wb6b

Well, I'm several days BEHIND on what I had planned on this project, but I have some baseline results finally.? ?(Had pancreatitis last week and gallbladder removed Monday and laid up a bit, then struggled several days with an open-repeater ics-ctrl repeater controller raspberry pi project to completion).

First goal was to develop a homebrew measurement lab in place of a spectrum analyzer, to allow baseline measurements of harmonic output from a stock ubitx v3/4.? ?(Prior to modification to add in a daughterboard filter relay repair described previously.)

Using a 50 ohm/16.6K ohm voltage divider built on top of a Heathkit cantenna ( 2 100 ohm in parallel to make the 50 ohm, checked with very low SWR well beyond 30 MHz on antenna analyzer to be sure not wirewound resistors) and 6 100K resistors in parallel to make the top of the voltage divider), created approximatelly 50 dB attentuator.

Then double shielded BNC coax patch cord to selected bnc attenuator right at the input to an ICOM 718 receiver.??

Tonight was initial tests.? ?First problem:? V4.3 of software would not go into CW mode no matter what I tried on the key terminals.? ?Finally gave up and reverted to my own modified v2.0 of the ubitx code which does transmit.? ?Next problem was my radio shack "wattmeter" indicates rather low outputs.....but may not be accurate at all so I just went forward.

"Attentuator" is the ADDITIONAL attenuator beyond the estimated 50 db at the cantenna.

Mode? ? ? ?Freq? ? ? Meas.Watts? Attenuator? ?Fundamental? ?2nd Harmonic? ?3rd Harmonic? 4th Harmonic? ?5th Harmonic
CW? ? ? ? ?3.505? ? ? ? 2? ? ? ? ? ? ? ? ? 20 dB? ? ? ? ? S9+25? ? ? ? ? ? ? ?S8? ? ? ? ? ? ? ? ? ? ? ? S8? ? ? ? ? ? ? ?not meas? ? ? ? ? S8
CW? ? ? ? ?7.080? ? ? ? 1? ? ? ? ? ? ? ? ? 20 dB? ? ? ? ? S9+25? ? ? ? ? ? ? ?S6? ? ? ? ? ? ? ? ? ? ? ? S8.5? ? ? ? ? ?not? meas? ? ? ? ? not meas


All I have is the little LCD screen of the ICOM 718....but the readings were quite steady and the tuning in of the signal was not critical at all.?For the very first crack at? this EVER in my life, I was much more impressed with the measurement setup than I was with the problems I was inhaving the little uBitx to perform for me to allow testing.? ? I'll fiddle with this a bit more to be sure I'm happy with some baseline readings before I begin hacking traces and building the circuit board I have for the outboard relays.? ?I may have some other "power meters"? [these allare just simple rf voltmeters posing as wattmeters]? and see if I get any more believable answers.??

Thanks,

gordon gibby kx4z

I've always said I love standards.

They're just so FLEXIBLE!

73,
Gwen NG3P

When changing frequency or trying to step through the menus my encoder has a very annoying behavior. Sometimes with a single click it will act like 2 or 3 clicks. Sometimes you have to rotate it 2 or 3 clicks to make any change at all. So for example: lets say you are on 7.039.900 and you want to go to 7.040.000. You might have to do something like this: Right one click and you are on 7.040.200, left one click - no change, left one click and you are on 7.039.900, right one click and you are on 7.040.100..... and so on until you eventually land on 7.040.000.

I built two Raduino clones and they both operate this way. One is breadboarded with a parallel display and the other is built on a VK4PLN board with an I2C display. Both are running KD8CEC code V1.08.

The encoder I'm using is a brand new Bourns PEC16-4220F-S0024 part that I bought from Digikey. I have tried it with 0.01uf caps, 0.22uf caps and with no caps on the EncA and EncB lines and basically saw no change in behavior. ?I have used that encoder part in some other projects without issue. I tried one of the cheap e-bay encoders and it was even more annoying. Any ideas would be appreciated.

Spot on Iz.

WA8TOD