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CW key sticking with Nextion LCD, still getting RF in


Joe Puma
 

Hi,

So I made some progress with adding the diodes on the RX and TX blocking the discharge of the caps near by. And I was able to get the CW key to stop sticking with a .01uf on the blue line to ground on the Nextion display. But there is still one more bugger. The problem does not happen all the time but around 14mhz and 28mhz there is some RF getting in the delay portion of when you unkey the CW keyer, If I make delay 0 no problem. but with it on It shows a power and swr boost durning that delay time on the meter and I hear a hiss in speaker. My auto tuner chatters making it go out of tune for the next transmit.

Its intermittent now but it definitely seem like RF getting into that delay, if that makes sense. Since I’ve been making great use of filtering with .01uf on other areas I am thinking I can use a cap to fix this problem, but where? I did PTT, but I dont think I put a .01uf on the CW key yet

To add, I don't see the problem when I am on a dummy load, just my antenna system and it seems to act wacky if my tuner tunes it to a weird spot. RF is present. Then sometimes I get a good tune and when I unkey, CW It ends clean. I want to say that the radio is not all to blame either because on my commercial radio, same antenna on 11 meters around 29.500 if I key my radio full power and hit max watts out, the whole radio resets and clears memory, so I might have some wild RF issues, the EFHW is near by the house and over the roof.


the sage continues…

Joe
KD2NFC

On Apr 10, 2019, at 6:17 PM, Joe KD2NFC <kd2nfc@gmail.com> wrote:

At first I wrapped a barrel chock on the wires of Nextion. It helped a little. The I put a .01uf on the blue wire of Nextion and ground and that stopped the key from sticking.

Joe


Sent from my iPhone

On Apr 10, 2019, at 12:46 PM, d balfour <davesters@hotmail.com> wrote:

I didn't follow the link but You might try a torrid on the orange line and/or between the raduino and nextion.



Sam Tedesco
 

U have a choke on the efhw? I have a very similar set up and run into similar issues without one. I use an pvc wound coax choke.  Or, try adding/removing a couple feet of radiator line? Intermittent sucks.


Joe Puma
 

Hi Sam, 

I had a pvc air wound one too. 21ft of coax, but it was some real crappy coax so I took it off. I will try a better one. I was eyeing an inline choke, I was thinking of getting the my antenna one. 




On Apr 11, 2019, at 2:51 PM, Sam Tedesco <stedesco619@...> wrote:

U have a choke on the efhw? I have a very similar set up and run into similar issues without one. I use an pvc wound coax choke.  Or, try adding/removing a couple feet of radiator line? Intermittent sucks.


Evan Hand
 

I had similar problems when connected to an off center fed dipole.  i solved my issues with clip on ferrite on the coax going to the antenna.  That may work for you.  Maybe a ferrite between the uBitx and the tuner, or an isolation balun

The issue was RF on the braid of the coax.

FWIW
73
Evan
AC9TU


Joe Puma
 

I can try that on the short patch from tuner to meter or radio as I have LM240 there. but the line going to antenna is RG213. So I don’t have a clip ferrite that big.  




On Apr 11, 2019, at 3:40 PM, Evan Hand <elhandjr@...> wrote:

I had similar problems when connected to an off center fed dipole.  i solved my issues with clip on ferrite on the coax going to the antenna.  That may work for you.  Maybe a ferrite between the uBitx and the tuner, or an isolation balun

The issue was RF on the braid of the coax.

FWIW
73
Evan
AC9TU


Jack Brabham - KZ5A <kz5a@...>
 

Antennas like the OCFD, EFHW , really even a plain dipole will utilize the coax shield as part of the antenna's counterpoise if they can,  resulting in  RF in the shack, excessive noise pick-up, and pattern distortion.   The EFHW requires a counterpoise of ~10% of the main element length, the others not so much.

The way to prevent this problem is a choke unun at the antenna feedpoint.   This can be as simple as several turns of coax in 8 to 12 inch loops,  or at qrp levels several turns of  RG-174 wound around something like a FT240-43 core. 

I had a Balun Designs 2KW Unun that was the center of a 160/80 trap dipole, after a few years the electrical box it was mounted in deterioated and it went to the junk box.

Recently it's "parts" have now been resurrected and it now forms the input choke unun for my 4 core 49/1 EFHW transformer, all in the same 4x4x6 junction box.

Fighting RF in the shack problems never ends until you find a way to keep it out.

73 Jack KZ5A







On 4/11/2019 1:44 PM, Joe Puma wrote:
I can try that on the short patch from tuner to meter or radio as I have LM240 there. but the line going to antenna is RG213. So I don’t have a clip ferrite that big.  




On Apr 11, 2019, at 3:40 PM, Evan Hand <elhandjr@...> wrote:

I had similar problems when connected to an off center fed dipole.  i solved my issues with clip on ferrite on the coax going to the antenna.  That may work for you.  Maybe a ferrite between the uBitx and the tuner, or an isolation balun

The issue was RF on the braid of the coax.

FWIW
73
Evan
AC9TU



Joe Puma
 

I ordered the myantenna inline choke I posted. Theres a lot of good things said about so we will see. I have a 3 core 49:1 unun for efhw. before i had a 9:1 unun and a random wire. Had the same issues there. I got grounding, counterpoise, all types of stuff…nothing has really combated the issue, getting closer though. I put 3 ferrites on the cable it helped a little with the tuner chatter but still hear some RF hissing in the speaker.  Today I am redoing all the cabling in the radio with good shielded wire with foil wrapping. 


Joe
KDNFC


On Apr 11, 2019, at 6:09 PM, Jack Brabham - KZ5A <kz5a@...> wrote:

Antennas like the OCFD, EFHW , really even a plain dipole will utilize the coax shield as part of the antenna's counterpoise if they can,  resulting in  RF in the shack, excessive noise pick-up, and pattern distortion.   The EFHW requires a counterpoise of ~10% of the main element length, the others not so much.

The way to prevent this problem is a choke unun at the antenna feedpoint.   This can be as simple as several turns of coax in 8 to 12 inch loops,  or at qrp levels several turns of  RG-174 wound around something like a FT240-43 core. 

I had a Balun Designs 2KW Unun that was the center of a 160/80 trap dipole, after a few years the electrical box it was mounted in deterioated and it went to the junk box.

Recently it's "parts" have now been resurrected and it now forms the input choke unun for my 4 core 49/1 EFHW transformer, all in the same 4x4x6 junction box.

Fighting RF in the shack problems never ends until you find a way to keep it out.

73 Jack KZ5A







On 4/11/2019 1:44 PM, Joe Puma wrote:
I can try that on the short patch from tuner to meter or radio as I have LM240 there. but the line going to antenna is RG213. So I don’t have a clip ferrite that big.  




On Apr 11, 2019, at 3:40 PM, Evan Hand <elhandjr@...> wrote:

I had similar problems when connected to an off center fed dipole.  i solved my issues with clip on ferrite on the coax going to the antenna.  That may work for you.  Maybe a ferrite between the uBitx and the tuner, or an isolation balun

The issue was RF on the braid of the coax.

FWIW
73
Evan
AC9TU




Joe Puma
 

Happy to say running shielded wires and making sure metal contacts like mic plug is grounding to case and everything else. I am not hearing any RF in the CW delay on my antenna. 



image1.jpeg



On Apr 11, 2019, at 2:57 PM, Joe Puma via Groups.Io <kd2nfc@...> wrote:

Hi Sam, 

I had a pvc air wound one too. 21ft of coax, but it was some real crappy coax so I took it off. I will try a better one. I was eyeing an inline choke, I was thinking of getting the my antenna one. 




On Apr 11, 2019, at 2:51 PM, Sam Tedesco <stedesco619@...> wrote:

U have a choke on the efhw? I have a very similar set up and run into similar issues without one. I use an pvc wound coax choke.  Or, try adding/removing a couple feet of radiator line? Intermittent sucks.


_Dave_ AD0B
 

My fix for sticky controls
I have had rf on the ptt on 20. SWR was 1:1 My solution was to put a choke on the mic wires inside the box. Can imagine that using a small toroid on the key wires would help.
I use these https://www.arrow.com/en/products/5943000301/fair-rite-products.

I don't have hardly any shielded wire.

If you have rf on the circuit after you have put a choke on it you don't have enough choke.
I reviewed w1his articles. Had a lot of good ideas.


Jack Brabham - KZ5A <kz5a@...>
 

There is a uBitx "keying" board by W0EB on QRP Guys, might be relevant to your issue.

https://qrpguys.com/ubitx-cw-conditioning-adapter

73 Jack KZ5A