swr bridge re use+ repair

[p.larner]

why is that,as i said could the wrong torroids cause this?

[vk4ffab]

why is that,as i said could the wrong torroids cause this?

Without greater information, pictures and other such tests, my gut says user error in the build. You have a VNA, do an S21 on both SWR meters and see what is what from 1 to 30mhz. An swr meter is essentially a pass though as far as anything connected to it is concerned, it should be invisible and not add any load to the system. Grab a stack of 3 or 4 of these riods you used and pass them over an sma patch cable and put them on the VNA for an S21.

Without data we can only offer advice, with hard data we can look over your build for obvious errors, I cant see how the torriods can be placing such a load into the system. It should be just a single wire passing though the center, its not adding and tranformative effects, a poor choice of material will effect how accurate its measurements will be over frequency, becoming poorer at higher frequencies.

Here's one i prepared earlier. Your S21 should look something like the image below.

[vk4ffab]

why is that,as i said could the wrong torroids cause this?

Here is a random green ferret, well no so random, i use these for other things,



its a little more lossy than other ferret mixes, but would be suitable for HF



This is a type 43 mix sleeve, a little less lossy across HF



So, if the pass through of your SWR meter does not look like any of the above plots, you did something wrong and if the ferrite mix you used does not present a rather flat S21 from 1 to 30mhz, then they are useless for the task. Post some pictures, lets see what you have going on.

[p.larner]

would you have the artwork to the bridge shown so i can etch one?.

[vk4ffab]

would you have the artwork to the bridge shown so i can etch one?.

I am not sure that the 50ohm resistors I used are commonly available, or the huge binocular, it was made with what crap I had here in mind, not actual repeatability. It based off the schematic by Diz at Kits and Parts, beafed up to take 200w continious. He sells a complete kit for 12 bucks and a bare PCB for 4 bucks. Pretty sure there are chinese clones of this on ebay as well for very little money.

I can teach you how to layout a pcb and have it sent off to china for making. 5 pcb 100x100mm cost like 5 bucks delivered.

[p.larner]

how many turns doe T1+ T2 have on there secondarys?.

[VK2AZT]

The diagram shows that the secondaries take 10 turns. No idea what gauge wire is used but a thin diameter would be best.

[vk4ffab]

how many turns doe T1+ T2 have on there secondarys?.

It depends on the amount of power you are driving though it and the ma rating of the meters you are using. For mine, its designed so that the tapped off voltage is a maximum of 5V at 200W as the maximum input voltage to the ADC i am using is 5V.

But if you are using physical meters, you want the turns ratio to give you the maximum defection at the highest power the meter will see. As designed in the schematic, its 10 turns for 5W continuous with 50ma meters. Which should be fine for 50 to 100w with appropriately rated 50ohm resistors.

[A.Z.]

well the ratio also affects the min measurable power btw

[p.larner]

how many turns doe T1+ T2 have on there secondarys?.

It depends on the amount of power you are driving though it and the ma rating of the meters you are using. For mine, its designed so that the tapped off voltage is a maximum of 5V at 200W as the maximum input voltage to the ADC i am using is 5V.

But if you are using physical meters, you want the turns ratio to give you the maximum defection at the highest power the meter will see. As designed in the schematic, its 10 turns for 5W continuous with 50ma meters. Which should be fine for 50 to 100w with appropriately rated 50ohm resistors. do you mean 50 micro amp not milli?.

[p.larner]

well i rebuilt this coupler(see pdf),the first attempt was using unknown torroid cores,this made the swr rea 3+ when inline between my swr meter and atu,i was going to try and get some 43 torroids from a rally on sunday but there was none there,i got 10x ft-50 43 mix torroids from ebay,now its working ok,73.

[A.Z.]

I believe the main issue is the fact that you're using torroids, while any other uses toroids

[p.larner]

does the lh side go to the rig or rh side on the pcb,all it says is 50 ohm in 50 ohm out,is it the same convention,ie power input from the left?,i am unsure how to connect it,thanks in advance for a basic question.

[vk4ffab]

does the lh side go to the rig or rh side on the pcb,all it says is 50 ohm in 50 ohm out,is it the same convention,ie power input from the left?,i am unsure how to connect it,thanks in advance for a basic question.

Without looking at your schematic, or how you built the bridge, there is an input side and an output side in relation to the meter display, you can reverse the input and output and it will reverse the meter movements, IE FWD becomes REV. So even if its unmarked in your document, you can determine experimentally which is which.

[p.larner]

this is what i built see pf,its to fit inside an atu,i dont want to have to rewire it once in,hence need to know what side goes to the rig,all it says on the pf is 50 ohm in 50 ohm out,!.

[vk4ffab]

this is what i built see pf,its to fit inside an atu,i dont want to have to rewire it once in,hence need to know what side goes to the rig,all it says on the pf is 50 ohm in 50 ohm out,!.

Take a look at your linked file again, its all in there in one of the diagrams. Big labels saying IN and OUT.

[p.larner]

i see the in and out but is in from the rig or antenna,its confusing.

[A.Z.]

so long, and may we never meet again.

[vk4ffab]

i see the in and out but is in from the rig or antenna,its confusing.

No idea, but, if you think of input and output as in which way the RF travels through the device while making a measurement, In and Out then make sense. Power travels from the transmitter through the device to the antenna you are trying to measure.