KL203P and SWR

Like many of us we are back on band but a little rusty.The QRP set up this end is a Uniden 2830 With a 30 amp power supply and a Zetagi HP1000 transmatch to an old half wave dipole. So far connected to the transmatch once set on the ROS The SWR is 1:2, and works well as the radio puts out Pep about 20w

I decided to buy the KL203P as it had had good reviews and it arrived yesterday and connected it with the correct patch leads. Once tested the SWR rose to 2 and the ROS off the scale, so turning it back to 10 setting the SWR drops to about 1:5 if the linear is used.

Is this the correct way to use? and should i then move from the ROS setting to the 100W notch? If I want to use QRP then I just want to reverse what I have done and adjust the settings and knobs.

Thank you in advance

I don't have the exact same Zetagi meter/tuner, this just has 10w and 100w all they do is change the sensitivity of the meter so you can get more accurate power readings if your SWR is 1.5 at 10W it should be the same at 100W I would have thought.

If I wasn't using the matcher on it I would tend to check my reading then take the meter out of line(especially using lower power) I always found I got far better results with a well-tuned antenna for the band as opposed to using the matcher/tuner.

Alan

Thank you Alan for your reply and thoughts, yes the antenna is well matched on QRP but you have to re calibrate when running the linear

Mark

The SWR shouldn't vary with the power level (unless you're using enough power to make something arc or melt!). Have you got the matcher/SWR meter between the radio and the amp or between the amp and the antenna?

Hi 26CT287

It’s radio - Amp -matcher/SWR - antenna.

So Radio patch lead to RTX on amp, Radio (Antenna) Patch lead to Tranceive On HP1000 Matcher and Antenna socket on HP1000 matcher to antenna.

Just checked again so QRP set ROS 1:2 , switch linear on ROS goes off the scale turn back and match in at 1:5

Hope that’s correct

Thank you

Mark

ROS is Italian for SWR (and French). When you have the meter set to ROS and you adjust the Set control, you're calibrating the meter in response to the amount of power going through it - "Forward" power - so it is right that when you up the power, the meter goes off the scale and you have to adjust the Set control before you adjust the actual tuning controls. It sounds as if things are working as they should.

Thank you its what thought so good news

It is a common myth that does the rounds when people say that swr does not change with power.

It shouldn't, but in the real world the sensitivity of the diodes used in 'low cost' swr meters and matchers varies with the power and so gives 'random' readings and are designed to be 'accurate' at lower powers and this is why some swr meters (Bird for example) cost so much.

Add to this, if you do not stop common mode currents, the outside of your coax will usually radiate and the higher power (ie the increased energy) can also give spurious readings.

I also have the Zetagi HP1000 transmatch amongst others and over the years I have found it to be pretty good, if a little overpriced from new these days.

With mine I had to connect a dummy load and then adjust the three trimmers inside for the power ranges to get accurate readings but it has proved to be very reliable and will match 'random wires' from 24 - 30 Mhz very impressively!

People get far too hung up over swr and if you connect 3 different swr meters you will usually get 3 different readings, just try and keep it as low as possible and use the matching capability of the HP1000 to achieve that if you need to!

Thank you Michael for coming back to me and taking the trouble to reply. The SWR on the 2 element Sirio beam is 1:2 QRP and rises to 2:5 with the linear how ever hard you use the HP1000 it just will not come down. So a short burst then work QRP Does the trick but i was wondering if a good HF matcher would tune the SWR even better ?

Mark

Hope you got it sussed