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Bj?rn

While there is no harm in having exact capacitances in the ATU-100, the PIC1938 is measuring only the forward and reflected voltages from the Sontheimer coupler (ie Tandem match) and goes through the steps to reduce the reflected voltage.

AFAIK, the tuner's tandem match is not measuring complex impedance nor the operating frequency to calculate a conjugate match. The algorithm is similar to you operating a manual L-match tuner, and is merely searching for the lowest reflected voltage. It does a good job with a reasonable parts count...

Owen Duffy touches on this subject as it relates to binocular cores vs separate cores



73 de Russ, va3rr

Hi David,

Efficiency depends on style of winding, core dimensions and attention to details when construction the transformer. For example tight winding on the core and short wires at primary side play big role in good result. See my comparison tests on FT140-43


I never got to 98-99% range but managed 94.4% using FT82A-43 using KN5L method of wind. It also was only on 20m and 17m band, other bands were 91-92.?

Owen Duffy was initially sceptical as popular FT240-43 with 14:2 turns has efficiency of 82-84% at best. However, 3xFT240-52 got his approval as efficiency was over 90% with 14:2 turns. Still you need to wind it tight and look after construction details. I for instance use FT240-43 and FT140-43 inside to improve efficiency and at base QTH I use transformer which has two FT240-43 and two FT140-43 in them. Efficiency is in the range of 92-93% on most bands.

Owen also recommends method to measure efficiency of transformer by connecting antenna terminal through 2450ohm resistor to S21 input. Resistor and input impedance form voltage divider and you can calculate losses/attenuation of that system. In my case it was -17.1db as resistor was of slightly higher value than 2450ohm.

You can read transmission losses (blue line) of the system subtract losses of voltage divider to get transformer losses.?

?

Example of measuring setup


I hope this will help you to explore and experiment with 49:1 transformers and antennas.

GL 73 Marek

The firmware update was very easy and the 1.6 firmware performs better in matching than the 1.5.
I have updated 3 ATU-10s to use with TX-500 and IC-705.

73 - Dave, N4ELM

Thank you both for your answers'!
I want the algorithms to be as effficient as possible and it should be better to not have negative jumps in the applied capacitances so I will compensate for the missing pF. It should be better as the algorithms should expect the binary values to have a relatively linear relationship with the actual capacitance.

I have the components and it is only a matter of adding a few of them in parallell so not a big deal.

Bj?rn

as long as i tunes ok still i dont see that it matters.

I'm considering adding an ATU-10 to my FT-818 for POTA etc. and those I'm seeing on the various sites are 1.5 firmware versions not 1.6 versions. I've Googled "how to update firmware ATU-10 but haven't come across any info. Can someone point me in the right direction? Any suggestions for which avenue from whcih to purchase one? eBay, Aliexpress, Bangood, etc?

Thank you!
--
Rod

David;

For the KN5L transformer (2xFT114-43 toroids), John's work is found at:



For the Owen Duffy transformer (2643625002 core), his articles start at:

and;



I don't have the equipment (or knowledge) to either valid or refute the data. I can say that Owen Duffy was critical of early 49:1 transformer designs.

73 de Russ, va3rr

Hi, Bjorn

People, how did you find your 90-98% efficiency of 1:49 transformer ?
I would like to find it too.

Hello all!
I have an ATU-100 where I have had problems with broken SMD caps so now I have replaced them all with 3kV disk caps instead.
However when I measure the capacitance between center and ground in test mode I get non-linear values out when stepping through the 128 different combinations.

I understand it is probably due to my capacitors are not exact in value as the spec says some % more or less.
My idea is to make the stepping through all possible combinations as linear as practically possible by adding or removing capacitance.

My question is what to write to the EEPROM settings regarding the cap values? Is it the exakt measured values of the capacitors before inserting or is it the measured values between center and ground connector? When measuring both stray capacitans and inductance are involved in the actual values.
It could be that the software compensates for known stray capacitance on the PCB as it should be possibly known at time of designing the software and fairly consistent between PCBs when manufactured.

Also, does the software do a deacent job even if there are non-linearities in the capacitor range?
And also, is my method not good as I measure the capacitance using a frequency around a few hunder khz which could possibly affect measured values due to stray inductance?

By 'non-linear' above I mean that when increasing the binary value the capacitance actually get lowered. This happens if e.g. capacitor value activated by bit 4 is lower than the combined capacitors of bit 3, 2, 1 and 0 when switching from value 15 to 16.

Hi Paul, Yes, the female connectors can be a bit of a pain. I tend to just make up a multi-pin connectors as required, and they seem to be a little more reliable.
Anyway, is sounds like you are back up and running with the OLED display.

Picked mine up from NewDIYTech.com Good build quality. Prefer my T1 but the ATU-10 is great for the price and availability. Not to mention it’s feature set.?

You can see some of my testing here:?

Joshua
N5FY

Hi, Stig

Hi Stephan,

I strongly recommend KN5L method, if you are still looking for 6m band make primary connections as short as possible.

I tested my repaired ATU-10 with Long Wire antenna in the garden and it worked with SWR below 1.5:1 on all bands from 80 to 10. I am using 9:1 on FT140-43 3x7 turns and 12.5mtr (41feet) wire. The big test will be this Sunday when I plant to use it for SOTA activation on local hill. You never know we might have S2S.

I will post results next week.

73 Marek

Hi Rod.

I have purges the AT-15 variant, but this drains the battery twice as fast in OFF, as when it is ON, so stay away from this model.

73 de OZ3XO - Stig.

Any recommendations for best outlets from which to purchase an ATU-10?
Any to avoid?

If any have had relevant experience with one of these and a FT-818 I'm all ears.?

Thanks.
--
Rod

Well it now has a semi working display,looks like an iffy dupont lead connector,i hate them with a vengance,total crappy idea!.

well i have used an arduino uno with a test sketch,all my oled displays work fine,need to hunt down my programer now,at least i now know the displays are ok,can rf corupt the pic fw on these?.73 m3vuv