Date   

Re: Antenna Question #antennas #v3

Gordon Gibby
 

Be mindful of a lot of metal on the roof. We have installed antennas on the top of two professional buildings, that both had extensive metal flashing and extensive  lightning arresting systems.  

These appear to create RF coupling to the antenna that we placed, and we had to move the antenna as far away from them as possible to get in and impedances to look anything like what we are used to.   When the antenna was 5-8 feet or so above all of this metal, impedances in the five ohm range were measured which should have been 50 to 75     We were forced to move antennas way off the roof to the side or above to get manageable impedances.   

Gordon. KX4z 




On Mar 13, 2020, at 16:38, Joel Caulkins/N6ALT <caulktel@...> wrote:

Good news Chris! It never hurts to have the landlords blessing. I hope it all works out out.

Joel
N6ALT


Re: Antenna Question #antennas #v3

 

Good news Chris! It never hurts to have the landlords blessing. I hope it all works out out.

Joel
N6ALT


Re: Antenna Question #antennas #v3

Christopher Miller
 

This is true, the maintenance manager is in fact a cber. I am still thrilled at the prospect at having a dipole at 40 feet. And my landlord wants it.


Re: Antenna Question #antennas #v3

iz oos
 

That's great! Long life to CBers and SWL!


Il 13/mar/2020 20:32, "Christopher Miller" <djmalak2k6@...> ha scritto:
Ok, so the sky’s opened and a choir of angles sang. 

My apartment manager and the head maintenance guy came over to view the splendor of the UBITx.

They both were impressed that I got wwv at 10 MHz. They wanted to know what it meant.... I simply said it means the radio is calibrated and working.

They looked disappointed but then the magic happened.

They want to install a long wire or dipole on my roof. I told them I wasn’t going 40 feet up but my maintenance guy who has cb experience wants to do it. 

So I now have a bitx with a 20 meter dipole at 40 feet. This should be fun.

KF4FTR


Re: Antenna Question #antennas #v3

Christopher Miller
 

Ok, so the sky’s opened and a choir of angles sang. 

My apartment manager and the head maintenance guy came over to view the splendor of the UBITx.

They both were impressed that I got wwv at 10 MHz. They wanted to know what it meant.... I simply said it means the radio is calibrated and working.

They looked disappointed but then the magic happened.

They want to install a long wire or dipole on my roof. I told them I wasn’t going 40 feet up but my maintenance guy who has cb experience wants to do it. 

So I now have a bitx with a 20 meter dipole at 40 feet. This should be fun.

KF4FTR


Thank you

Christopher Miller
 

I hope this works, this is my first attempt to post. I received my bitx v3 yesterday and took a long time before connecting it to power because I didn’t want to smoke anything. With help from the original Elmer whom can be identified if they wish, and another ham cheering me on I had the guts to power on my first uBITx v3. I have tuned to wwv and with my dipole a mess across the floor I can clearly hear it at 10.000 with a half wave 20 meter dipole.

I am over the moon, the case is even the color of the tempo one my dad purchased for my twin and I as kids. I want to thank the community at large and the ham that sent me a rig. I have to find out how to pay it back now.

Hams are the best.

Chris KF4FTR


Re: Crystal Filter Termination

iz oos
 

Mini Circuits transformers are really good and many really wideband. Having said this, I think up to 15mhz winding one is cheaper and will be adequate. For higher frequencies higher than 15mhz it is likely to notice a difference.


Il 13/mar/2020 13:01, "Ravi Miranda" <ravimiranda@...> ha scritto:
Hi,

Doing some further research, are there any off-the-shelf transformers
that can be used for T5 and T6 (Crystal filter Termination)
https://www.hfsignals.com/wp-content/uploads/2019/02/ubitx_v5.pdf

Such as this: https://www.minicircuits.com/pdfs/T2-1T-KK81.pdf

Would this work instead of winding one?

Best 73,

Ravi/M0RVI

--
I'm here to add more value to the world than I'm using up.




Re: Crystal Filter Termination

 

Hi again,

Mini-circuits says (except for DC isolation) RF performance is similar between the types:

https://www.minicircuits.com/app/AN20-001.pdf

73,


Mark


Re: Crystal Filter Termination

 

Hi,

I suspect to simplify construction, they wind all these transformers the same.  Then to use them in that part of the circuit (simplify the traces?) they used them as autotransformers.  Unless, the schematic is not following what was done in the actual construction.  T8 is like that too.  I most often see regular transformers used in situations like this -- not sure if one way is better than the other.

73,


Mark


Re: Crystal Filter Termination

 

The better way would be to use the primary and secondary windings to make a 1:4 transformer..

At 13/03/2020, you wrote:
Hi,

Doing some further research, are there any off-the-shelf transformers
that can be used for T5 and T6 (Crystal filter Termination)
https://www.hfsignals.com/wp-content/uploads/2019/02/ubitx_v5.pdf

Such as this: https://www.minicircuits.com/pdfs/T2-1T-KK81.pdf

Would this work instead of winding one?

Best 73,

Ravi/M0RVI


Re: Crystal Filter Termination

 

Hi Ravi,

I think the ohm ratio is wrong on that one.  From the schematic, the originals look like 2:1 winding ratio autotransformers which will give a 4:1 ohm ratio.  Otherwise I don't see why you can't switch.

73,


Mark.


Re: Transmit Output Power (CW) #v5

 

Hi Rob,

It would be interesting to see "before" measurements.

One trick on viewing SMD parts is to take a good picture with a smartphone or digital camera and then zoom in to view the fine print.  SMD parts typically don't have real names on them like "2n3904" but have codes.  There are code lists on the web to help translate them though.

To check power at lower power levels (like the ubitx) you can use a diode RF probe.  Easy to make from scratch or as a kit.  Some QRP dummy loads have them built in (e.g. Elecraft, QRPGuys, QRP-Labs all have them).

If I remember correctly, I think changing Q90 and its biasing makes the biggest different in evening the output.

73,


Mark


Re: Crystal Filter Termination

 

Go for it Ravi, good find! much smaller fooprint.

Raj

At 13/03/2020, you wrote:
Hi,

Doing some further research, are there any off-the-shelf transformers
that can be used for T5 and T6 (Crystal filter Termination)
https://www.hfsignals.com/wp-content/uploads/2019/02/ubitx_v5.pdf

Such as this: https://www.minicircuits.com/pdfs/T2-1T-KK81.pdf

Would this work instead of winding one?

Best 73,

Ravi/M0RVI


Crystal Filter Termination

Ravi Miranda
 

Hi,

Doing some further research, are there any off-the-shelf transformers
that can be used for T5 and T6 (Crystal filter Termination)
https://www.hfsignals.com/wp-content/uploads/2019/02/ubitx_v5.pdf

Such as this: https://www.minicircuits.com/pdfs/T2-1T-KK81.pdf

Would this work instead of winding one?

Best 73,

Ravi/M0RVI

--
I'm here to add more value to the world than I'm using up.


Re: uBitx v6 Microphone #v6

Rene
 

Okay, you can see the hole for the screw, after pulling up the raiduno it wil fit but i think cause of all the problems i had, som contacts will not connect with the motherboard


Re: Transmit Output Power (CW) #v5

Rob French (KC4UPR)
 

I do have a V5 board.  To be clear, I have not yet made any modifications to the transmit chain... the only thing I have done is adjust RV1 to increase the output power on 80M to about 12W.  Before I did that, the pot was set at about half way, so it would be easy enough to turn RV1 back to a half-turn, and it should pretty much be what it was from the factory, +/- a few tenths of a watt.  I could then take reasonable "before" measurements.

I can't tell by looking what Q90 is (tiny little thing...), but based on the official V5 schematic, it should be an SMD 2N3904.  The rest of the pre-driver/driver transistors (6 of them) are all 2N3904, by the looks of them.

My power meter is built into an automatic antenna tuner designed for up to 150W.  So I'm sure it's not super accurate.

Thanks for all the feedback!
-Rob KC4UPR


Re: uBitx v6 Microphone #v6

Rene
 

Oké iedereen, bedankt voor het beantwoorden. De C die ik op de microfoonlijn moet plaatsen, is misschien een oplossing? Maar voorlopig heb ik gisteren geprobeerd om de radio stap voor stap in elkaar te zetten ... Ik ben begonnen met het moederbord en daarna heb ik de raduno erop gezet. Ik heb de draden aangesloten en ...... het werkt, audio niet zo geweldig en microfoon ook niet zo geweldig, maar geen toon aan de zijkant. Maar .... toen probeerde ik de voorkant van de sluiting te plaatsen en ik zag (vanmiddag maak ik foto's) dat het raduno bord en het scherm niet in de voorkant passen ?? Ik moet de raduino ongeveer 5 of 6 mm uit de connector trekken. De montage van de raduino is slecht en past niet goed. Dus ik heb wat kleine o-ringen gevonden and i am gonna place them under the mainboard for just that .5mm rise. The next problem is that the hole's for mike, phones and volume are  on the right place...😶😶 so this story continues


Re: Transmit Output Power (CW) #v5

jim
 

Well ...anything you've got is better than nothing ...back in the old days, folks used a wave-meter (gdo in diode position) to check for spurs/harmonics ..was hoping for some before/after measurements...ah well

thanks, Jim

On Friday, March 13, 2020, 1:59:53 AM UTC, Rob French (KC4UPR) <kc4upr@...> wrote:


Jim, no, I don't really have a way to check for that.  I suppose I could use my SDR dongle as a poor man's spectrum analyzer??? See what other spikes I get in the spectrum when I transmit?

I will note that, at the low end of 80 meters, prior to turning up RV1, I was only getting ~6.5W, so I'm wondering if my uBITX wasn't quite adjusted right from the factory... I wasn't getting 8 W anywhere.  Although, that probably also gets to Dave's point about different power meters, different measurements.


Re: Transmit Output Power (CW) #v5

_Dave_ AD0B
 


If you have a decent amp meter you can adjust RV2 and RV3. Don't try and set them by ear. Review. the procedure on line. All three RV adjusters adjust the final power out be it ditties or voice.  I got one unit that was weak on transmit and turning up RV1 brought it up to spec.

I have a spread sheet that has the approximate RF voltage at each transmitter stage as collected by my 30 year old scope. You would want an oscope to compare. Basically you see that each transformer decreases the voltage substantially but the 3 transistor array more than makes up and by the time it is to the next  transformer it is stronger than it was when it entered the prior stage. 

Personally I would not want to do a two tone test at this point. 
If you have done any modifications you are not in a position to see what if any difference they are making. Best return to stock to make that as good as possible. 

If yours is a v5 it should have the improved transistors in it. No? You should verify. 

I looked through this post and was not sure of the model version. 


--
73
Dave
ADOB
Raduino bracket and Ham_Made_Keys


Re: Transmit Output Power (CW) #v5

 

Hi Rob,

Well, what is the power meter you are using?  If it's a 100-200W maximum meter, certainly it will not have much accuracy down below 10W.

Do you have, or could you get, an oscilloscope?  That is a good method for setting SSB power out (using a 2-tone test signal).

73,


Mark