Anybody have a problem with SWR tune


Leonard A. Gucciardo KD2NEN
 

I have built 2 loop controllers. 1 for 1000watts and 1 for QRP. Both controllers behave the same when I go higher than 20 meters. The SWR tune starts tuning when I transmit and on the display the SWR jumps around and is not steady as well as the power meter goes into milliwatts. It is almost as if it is RF interference. If I manually request an SWR tune the loops tune up fine. If I key the mic on AM both controllers will keep on looping in and SWR tune. They tune to success pause then start tuning again. 14mhz and below are fine. It gets worse as you go higher in frequency. If I manually turn off SWR tune I can use the loop fine.
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LennyG KD2NEN


Patrick
 

I agree, sounds like rf interference and as if further shielding is needed.
Can you get some copper plating and make a shield to cover the SWR circuit?


Leonard A. Gucciardo KD2NEN
 

It does not matter if I take the SWR circuit and isolate it. Tried shielding did nothing. Loop controller functions amazing just a big annoyance.

Leonard A. Gucciardo
KD2NEN

On Feb 23, 2021, at 4:02 PM, Patrick <kd7wpq@...> wrote:

I agree, sounds like rf interference and as if further shielding is needed.
Can you get some copper plating and make a shield to cover the SWR circuit?

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LennyG KD2NEN


Patrick
 

Hmmm, I'm interested to know if there is a solution to the problem and being that my electronic skills are lacking I can't offer advice that's any better than I did but I am curious if someone else has some ideas on how to resolve the issue because it seems you found a bug that we should get sorted out and when i say we, I mean someone with more knowledge than I.

I do wish I could help more.

Anyone have any ideas?


Immo, DL5KB
 

hi Lenni,
do you use the same loop with both controllers? And also the same capacitor? Is it possible, that there are problems in tuning the loop >21 Mc? Backlash, endcapacity of capacitor? 
How have you shielded the swr bridge? picture? Are the wires to stepper enough blocked? is the enclosure of the controller „close“?
HF is a like a squirrel.
73, Immo, DL5KB 


Leonard A. Gucciardo KD2NEN
 

I have 2 different controllers. One I made for QRP and the other I built with a high powered breune bridge coupler for 1kw. The QRP controller uses the kits and parts tandem bridge coupler for 30 watts max. They are 2 separate controllers on 2 separate magnetic loops. Both exhibit the same behavior above 14mhz. I tried to modify software changing the average over points from 32 to 320 steps because I am using 100:1 steppers in each loop. The only thing in common are the common mode chokes I used on both controllers. Here is a picture.

On Feb 24, 2021, at 6:20 AM, Immo <dl5kb@...> wrote:

hi Lenni,
do you use the same loop with both controllers? And also the same capacitor? Is it possible, that there are problems in tuning the loop >21 Mc? Backlash, endcapacity of capacitor? 
How have you shielded the swr bridge? picture? Are the wires to stepper enough blocked? is the enclosure of the controller „close“?
HF is a like a squirrel.
73, Immo, DL5KB 

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LennyG KD2NEN


Immo, DL5KB
 

hi Lenni,
I have an iron case for for my SWR-bridges. It is close for up to 500W and there is no issue tunig up to 24Mc. I have also two capacitors tested, one butterfly-C with a 1: 100 geared stepper and another with a vac-C and a 1: 20 geared stepper. As I started my built, I had the little bridge after Kits and parts mounted only with copper-shields open in my controller case. There I had the issue, that automatic tuning was not possible over 18Mc. At least my Teensy won't work any more and I had to change it. It was to much straying HF inside the case. Today I have both bridges in a steel case and no problems any more. I use my loop inhouse, about 2 m (6ft) from my rig and the loop controller working up to 100W. The housing of the controller is made of double sided copper coated material. All sides (in- and outside) are soldered together and  grounded. The pictures show the bridge with two 8307. This one I can remove from controller and connected over cable, mount directly at the loop. Works fine!
So you have to prove your design, I believe. Good luck!
73, Immo, DL5KB


Leonard A. Gucciardo KD2NEN
 

Looks like that’s what I have to do with mine. I believe it is RF that is causing the issue because it is frequency dependent. I will place my couplers in an aluminum enclosure and remotely connect them. Thanks for the input I really appreciate it. Very nice job on that coupler.

Leonard A. Gucciardo
KD2NEN

On Feb 24, 2021, at 1:12 PM, Immo <dl5kb@...> wrote:

hi Lenni,
I have an iron case for for my SWR-bridges. It is close for up to 500W and there is no issue tunig up to 24Mc. I have also two capacitors tested, one butterfly-C with a 1: 100 geared stepper and another with a vac-C and a 1: 20 geared stepper. As I started my built, I had the little bridge after Kits and parts mounted only with copper-shields open in my controller case. There I had the issue, that automatic tuning was not possible over 18Mc. At least my Teensy won't work any more and I had to change it. It was to much straying HF inside the case. Today I have both bridges in a steel case and no problems any more. I use my loop inhouse, about 2 m (6ft) from my rig and the loop controller working up to 100W. The housing of the controller is made of double sided copper coated material. All sides (in- and outside) are soldered together and  grounded. The pictures show the bridge with two 8307. This one I can remove from controller and connected over cable, mount directly at the loop. Works fine!
So you have to prove your design, I believe. Good luck!
73, Immo, DL5KB
<SWR bridge in its case.JPG>
<SWR-Bridge closed.JPG>

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LennyG KD2NEN