Q R P e r

Many thanks to Joshua (KO4AWH) who shares the following guest post:

UPDATE: Please check out Joshua’s most recent review after updating the ATU-10 with new firmware. The results have improved dramatically.

by Joshua (KO4AWH)

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I had a bit of time to do some field tests and I recently acquired an ATU-10. So I jumped right in and did some ATU-10 Random Wire Testing. The testing was completed with a Tufteln 9:1 QRP Antenna configured with an elevated feed point sloper and a counterpoise hanging straight down. The coax feed was RG316 17′ with the ATU at the radio with a short jumper. Several different radiator lengths are used as mentioned below. The ATU-10 was sourced from newdiytech.com, price was $120.24 shipped to me in GA USA, Ordered June 25, delivered July 8th.

A quick list of ATU-10 Features:

• 0.91″ OLED Display that shows Power, SWR and internal battery remaining.
• USB-C Rechargeable LiPo 1.7Ah
• Grounding Lug
• Bypass Mode (When I set to this mode however it would tune anyways)
• Latching Relays (No power needed to keep in position. Hold tune with ATU off)
• Input port for communication with IC705 (and potentially others)
• 7 Inductors, 7 capacitors
  • (Elecraft QRP)
    • C array, pF 10, 20, 39, 82, 160, 330, 660
    • L array, uH 0.05, 0.11, 0.22, 0.45, 0.95, 1.9, 3.8
  • ATU-10
    • C array, pF 22, 47, 100, 220, 470, 1000, 2220
    • L array, uH 0.1, 0.22, 0.45, 1.0, 2.2, 4.5, 10.0
• USB-C firmware update (ATU shows up as a drive, simply copy the new firmware file to the device and it will automatically update)
• Weight 232g (8.1oz)
  • Tufteln Case adds 23g (.8oz) for a Total of 255g (8.9oz)
  • Compared to the T1 with cover for a total weight of 187g (6.5oz)

SWR measured with a RigExpert RigStick 320, Lab599 Discovery TX-500 and the ATU-10

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The test process was to first check the SWR on the antenna with no tuner. SWR values recorded from the TX500 and RigExpert Stick 320. Values recorded in the 2 columns under the “No Tuner” section. This was completed for each of the Bands listed in the table rows (see below). SWR values were the lowest in the band range for all recorded numbers.

The second test was with the ATU-10 tuned. I tuned the antenna with the ATU-10 from the tune function on the TX500 (to produce a tone at about 3w) and recorded the value on the ATU-10 and the TX500. When a SWR over 1.5 was achieved I would give several more tries to get the ATU-10 to tune. I then disconnected the radio and checked the SWR with the RigExpert 320 through the ATU-10. These three values are recorded in the “ATU-10 Tuned” columns.

The third test was the same as the previous but after tuning with the Elecraft T1.

These tests were then completed with the same setup with only a different radiator length. See the table name in each for the length. 31.5’ 41’ and 85’ were all used. Sorry, I did not 80m but probably should have.

Test Conclusions

I will keep this brief as the data is self explanatory. The ATU-10 is not a great tuner. Maybe it is just the one I got? The Elecraft T1 is excellent (not the intention of this testing but of course no surprise on the results). The ATU-10 I received from newdiytech.com was not DOA. It reads power level, shows an SWR level, Charges, clicks the internal relays etc. but it just doesn’t do a good job tuning the antenna. I will have to do some further testing and research on the device and see where this goes.

Other thoughts

Yes, a brief conclusion for sure. I am not very familiar with this ATU and to be honest I didn’t have very high expectations. The display with power and SWR reading was very attractive for me as well as the opportunity to offer another protection cover like I made for the T1.

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One reason I chose newdiytech.com was that they are one of the very few approved vendors for the (tr)uSDX and I have seen several times there they appear to have great customer support.

Did I mention the T1 is great? Currently they have shipping time from Elecraft listed as TBD due to chip shortages, I believe.

There is both a “Relay-Test” and “Manual-Test” file from the GitHub Repo by David Fainitski. You can load these firmware hex files and step through the L and C circuits. In a not so scientific manner, I watched Inductance and Capacitance through the open tuner and did in fact see changes with each step and hear clicks as well which at least tells me the relays are functioning. There is some discussion on the Groups.io page as well, honestly much of which I have not yet read.

That groups.io page is for the original ATU-100 as well as the ATU-10. One commenter believes the cap values should be updated for better agility to match the network. You can see this in the Features section above when comparing the T1 and ATU-10.

It also sounds like David is planning to work on updating the tuning algorithm. The community work on this ATU and so many other areas of HAM radio is such a great thing to see!

Joshua KO4AWH Tufteln Antennas

For those still Interested an ATU-10 case:https://www.etsy.com/listing/1266117729/atu-10-tuner-protection-case

Source: https://antiquewolrd.com
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