Topics

100W Automatic Antenna Tuner...


Bob Lunsford
 

Here's another item that may be of interest for you build-it-yourself hobbyists: An automatic antenna tuner. Costs $28 plus shipping for the kit...

Here are some specs for it:

Power supply range: 10 - 15 VDC
Max current : 450mA
Max working power: 100 watts
Max measured power: 150 watts
Minimum power for tuning start: 1 watt
Recommended maximum power while tuning not above 30 watts. (after tuning you can set 100 watts and work on this power)
Minimum measured power: 0.1 watt
Step for measurement on powers under 10 watts: 0.1 watt
Step for measurement on powers above 10 watts : 1 watt 
Power measurement accuracy : 10%
Maximum inductance set: 8.5 uH
Minimal step for setting inductance: 0.1 uH
Maximum installed capacity: 1870 pF
Minimal step for setting capacity: 10 pF






Patrick Ridge
 

The antenna tuner kit is available on Bangood for a few dollars less. The kit is mostly complete, but has a few issues. It comes with a nice, solid enclosure. I’m not sure it will handle more than 10 watts. 

Issues:
1. No clear instructions. YouTube to the rescue
2. The tuning capacitor knobs did not come with the necessary extension shaft. Mikes electronics to the rescue.
I am planning to make a short YouTube to address what I thought were shortcomings in the instructions and the YouTube videos I watched regarding this kit. Standby....

The kit is a value for the parts alone. Just be aware that it takes some effort and a few outside pieces that were not included to make it work.

73
Alan
AE0IX


On Aug 1, 2020, at 8:06 PM, Bob Lunsford via groups.io <nocrud222@...> wrote:


Here's another item that may be of interest for you build-it-yourself hobbyists: An automatic antenna tuner. Costs $28 plus shipping for the kit...

Here are some specs for it:

Power supply range: 10 - 15 VDC
Max current : 450mA
Max working power: 100 watts
Max measured power: 150 watts
Minimum power for tuning start: 1 watt
Recommended maximum power while tuning not above 30 watts. (after tuning you can set 100 watts and work on this power)
Minimum measured power: 0.1 watt
Step for measurement on powers under 10 watts: 0.1 watt
Step for measurement on powers above 10 watts : 1 watt 
Power measurement accuracy : 10%
Maximum inductance set: 8.5 uH
Minimal step for setting inductance: 0.1 uH
Maximum installed capacity: 1870 pF
Minimal step for setting capacity: 10 pF






Bob Lunsford
 

Further perusing eBay for offerings, I found other tuners. The specifications given were believable but of course they will not tell you the negatives, only the positives with a few elaborations. And it appears that the builder will still need to get an enclosure. No telling what it would take to make it perfect. Still, though, it beats the price of other auto-tuners on the market but everything like this comes with compromises. Myself, I'll stick to the manual tuner I mentioned previously since it is simplicity itself. One builder had a faulty switch in this kit but that was one builder's complaint before saying it was a good tuner once the fault was found and corrected. However, this simpler tuner is good enough for what I want to do with the V6. Also, there is a less expensive offering for the manual tuner: It's only $12 but they don't use PayPal.

Bob — KK5R

On Saturday, August 1, 2020, 10:37:07 PM EDT, Patrick Ridge via groups.io <apm80814@...> wrote:


The antenna tuner kit is available on Bangood for a few dollars less. The kit is mostly complete, but has a few issues. It comes with a nice, solid enclosure. I’m not sure it will handle more than 10 watts. 

Issues:
1. No clear instructions. YouTube to the rescue
2. The tuning capacitor knobs did not come with the necessary extension shaft. Mikes electronics to the rescue.
I am planning to make a short YouTube to address what I thought were shortcomings in the instructions and the YouTube videos I watched regarding this kit. Standby....

The kit is a value for the parts alone. Just be aware that it takes some effort and a few outside pieces that were not included to make it work.

73
Alan
AE0IX


On Aug 1, 2020, at 8:06 PM, Bob Lunsford via groups.io <nocrud222@...> wrote:


Here's another item that may be of interest for you build-it-yourself hobbyists: An automatic antenna tuner. Costs $28 plus shipping for the kit...

Here are some specs for it:

Power supply range: 10 - 15 VDC
Max current : 450mA
Max working power: 100 watts
Max measured power: 150 watts
Minimum power for tuning start: 1 watt
Recommended maximum power while tuning not above 30 watts. (after tuning you can set 100 watts and work on this power)
Minimum measured power: 0.1 watt
Step for measurement on powers under 10 watts: 0.1 watt
Step for measurement on powers above 10 watts : 1 watt 
Power measurement accuracy : 10%
Maximum inductance set: 8.5 uH
Minimal step for setting inductance: 0.1 uH
Maximum installed capacity: 1870 pF
Minimal step for setting capacity: 10 pF






Patrick Ridge
 

Re: the N7DDC auto tuner.

I looked for reviews first, decided to order it. This was a little over six weeks ago. For me, it entailed two orders, one for the circuit board and related components and another for the enclosure.

The enclosure arrived via China Post rather quickly. It was 28.00 USD shipped. It contains a few other pieces such as the antenna bulkhead connectors. It is a 3D printed item, but appears to be decently done. 

The circuit board has not arrived. 35.00 USD shipped. The tracking shows it stalled in Russia.

When and if it arrives, I'll assemble and give some further feedback...standby....

73
Alan
AE0IX

On Saturday, August 1, 2020, 08:56:38 PM MDT, Bob Lunsford via groups.io <nocrud222@...> wrote:


Further perusing eBay for offerings, I found other tuners. The specifications given were believable but of course they will not tell you the negatives, only the positives with a few elaborations. And it appears that the builder will still need to get an enclosure. No telling what it would take to make it perfect. Still, though, it beats the price of other auto-tuners on the market but everything like this comes with compromises. Myself, I'll stick to the manual tuner I mentioned previously since it is simplicity itself. One builder had a faulty switch in this kit but that was one builder's complaint before saying it was a good tuner once the fault was found and corrected. However, this simpler tuner is good enough for what I want to do with the V6. Also, there is a less expensive offering for the manual tuner: It's only $12 but they don't use PayPal.

Bob — KK5R

On Saturday, August 1, 2020, 10:37:07 PM EDT, Patrick Ridge via groups.io <apm80814@...> wrote:


The antenna tuner kit is available on Bangood for a few dollars less. The kit is mostly complete, but has a few issues. It comes with a nice, solid enclosure. I’m not sure it will handle more than 10 watts. 

Issues:
1. No clear instructions. YouTube to the rescue
2. The tuning capacitor knobs did not come with the necessary extension shaft. Mikes electronics to the rescue.
I am planning to make a short YouTube to address what I thought were shortcomings in the instructions and the YouTube videos I watched regarding this kit. Standby....

The kit is a value for the parts alone. Just be aware that it takes some effort and a few outside pieces that were not included to make it work.

73
Alan
AE0IX


On Aug 1, 2020, at 8:06 PM, Bob Lunsford via groups.io <nocrud222@...> wrote:


Here's another item that may be of interest for you build-it-yourself hobbyists: An automatic antenna tuner. Costs $28 plus shipping for the kit...

Here are some specs for it:

Power supply range: 10 - 15 VDC
Max current : 450mA
Max working power: 100 watts
Max measured power: 150 watts
Minimum power for tuning start: 1 watt
Recommended maximum power while tuning not above 30 watts. (after tuning you can set 100 watts and work on this power)
Minimum measured power: 0.1 watt
Step for measurement on powers under 10 watts: 0.1 watt
Step for measurement on powers above 10 watts : 1 watt 
Power measurement accuracy : 10%
Maximum inductance set: 8.5 uH
Minimal step for setting inductance: 0.1 uH
Maximum installed capacity: 1870 pF
Minimal step for setting capacity: 10 pF






Dave Dixon
 

I have a built and am running the auto atu being sold on ebay,you have to look around to see what you get and dont get luckily i chose one that came with all componants at the time i ardered the 3D printed case and built it and tried it on my 4 wire aerials at home and the auto tuned all 4 with no problems i ran 100 watts through the atu after intially using 5 watts to attain resonance suffice to say it handles 100 watts with no problems and the best auto atu for the money im very pleased i also spent 4 days out in the countryside using this atu with a minimum of 50 watts and had no problems and made many contacts on the aerial i used,this is based om my findings and experience of 4 days/nights last week operating hf cw with 50 watts on a icom 706 mk2g and 85 foot end fed via a 9;1 UNUN at 25 feet.The beauty is i built this myself and a great feeling of satisfaction of using a piece of equipment youve built.Despite my mini stroke last nov i managed the build okay.Regards.Dave G0AYD.... 

On Sun, 2 Aug 2020 at 04:24, Patrick Ridge via groups.io <apm80814=yahoo.com@groups.io> wrote:
Re: the N7DDC auto tuner.

I looked for reviews first, decided to order it. This was a little over six weeks ago. For me, it entailed two orders, one for the circuit board and related components and another for the enclosure.

The enclosure arrived via China Post rather quickly. It was 28.00 USD shipped. It contains a few other pieces such as the antenna bulkhead connectors. It is a 3D printed item, but appears to be decently done. 

The circuit board has not arrived. 35.00 USD shipped. The tracking shows it stalled in Russia.

When and if it arrives, I'll assemble and give some further feedback...standby....

73
Alan
AE0IX

On Saturday, August 1, 2020, 08:56:38 PM MDT, Bob Lunsford via groups.io <nocrud222=yahoo.com@groups.io> wrote:


Further perusing eBay for offerings, I found other tuners. The specifications given were believable but of course they will not tell you the negatives, only the positives with a few elaborations. And it appears that the builder will still need to get an enclosure. No telling what it would take to make it perfect. Still, though, it beats the price of other auto-tuners on the market but everything like this comes with compromises. Myself, I'll stick to the manual tuner I mentioned previously since it is simplicity itself. One builder had a faulty switch in this kit but that was one builder's complaint before saying it was a good tuner once the fault was found and corrected. However, this simpler tuner is good enough for what I want to do with the V6. Also, there is a less expensive offering for the manual tuner: It's only $12 but they don't use PayPal.

Bob — KK5R

On Saturday, August 1, 2020, 10:37:07 PM EDT, Patrick Ridge via groups.io <apm80814=yahoo.com@groups.io> wrote:


The antenna tuner kit is available on Bangood for a few dollars less. The kit is mostly complete, but has a few issues. It comes with a nice, solid enclosure. I’m not sure it will handle more than 10 watts. 

Issues:
1. No clear instructions. YouTube to the rescue
2. The tuning capacitor knobs did not come with the necessary extension shaft. Mikes electronics to the rescue.
I am planning to make a short YouTube to address what I thought were shortcomings in the instructions and the YouTube videos I watched regarding this kit. Standby....

The kit is a value for the parts alone. Just be aware that it takes some effort and a few outside pieces that were not included to make it work.

73
Alan
AE0IX


On Aug 1, 2020, at 8:06 PM, Bob Lunsford via groups.io <nocrud222=yahoo.com@groups.io> wrote:


Here's another item that may be of interest for you build-it-yourself hobbyists: An automatic antenna tuner. Costs $28 plus shipping for the kit...

Here are some specs for it:

Power supply range: 10 - 15 VDC
Max current : 450mA
Max working power: 100 watts
Max measured power: 150 watts
Minimum power for tuning start: 1 watt
Recommended maximum power while tuning not above 30 watts. (after tuning you can set 100 watts and work on this power)
Minimum measured power: 0.1 watt
Step for measurement on powers under 10 watts: 0.1 watt
Step for measurement on powers above 10 watts : 1 watt 
Power measurement accuracy : 10%
Maximum inductance set: 8.5 uH
Minimal step for setting inductance: 0.1 uH
Maximum installed capacity: 1870 pF
Minimal step for setting capacity: 10 pF






Lawrence Galea
 

I also ordered one, kit was posted, I was tracking it and it ended up in Russia back to the sender.
I got a refund as they are not sending anything due to Covid.


On Sun, Aug 2, 2020 at 5:24 AM Patrick Ridge via groups.io <apm80814=yahoo.com@groups.io> wrote:
Re: the N7DDC auto tuner.

I looked for reviews first, decided to order it. This was a little over six weeks ago. For me, it entailed two orders, one for the circuit board and related components and another for the enclosure.

The enclosure arrived via China Post rather quickly. It was 28.00 USD shipped. It contains a few other pieces such as the antenna bulkhead connectors. It is a 3D printed item, but appears to be decently done. 

The circuit board has not arrived. 35.00 USD shipped. The tracking shows it stalled in Russia.

When and if it arrives, I'll assemble and give some further feedback...standby....

73
Alan
AE0IX

On Saturday, August 1, 2020, 08:56:38 PM MDT, Bob Lunsford via groups.io <nocrud222=yahoo.com@groups.io> wrote:


Further perusing eBay for offerings, I found other tuners. The specifications given were believable but of course they will not tell you the negatives, only the positives with a few elaborations. And it appears that the builder will still need to get an enclosure. No telling what it would take to make it perfect. Still, though, it beats the price of other auto-tuners on the market but everything like this comes with compromises. Myself, I'll stick to the manual tuner I mentioned previously since it is simplicity itself. One builder had a faulty switch in this kit but that was one builder's complaint before saying it was a good tuner once the fault was found and corrected. However, this simpler tuner is good enough for what I want to do with the V6. Also, there is a less expensive offering for the manual tuner: It's only $12 but they don't use PayPal.

Bob — KK5R

On Saturday, August 1, 2020, 10:37:07 PM EDT, Patrick Ridge via groups.io <apm80814=yahoo.com@groups.io> wrote:


The antenna tuner kit is available on Bangood for a few dollars less. The kit is mostly complete, but has a few issues. It comes with a nice, solid enclosure. I’m not sure it will handle more than 10 watts. 

Issues:
1. No clear instructions. YouTube to the rescue
2. The tuning capacitor knobs did not come with the necessary extension shaft. Mikes electronics to the rescue.
I am planning to make a short YouTube to address what I thought were shortcomings in the instructions and the YouTube videos I watched regarding this kit. Standby....

The kit is a value for the parts alone. Just be aware that it takes some effort and a few outside pieces that were not included to make it work.

73
Alan
AE0IX


On Aug 1, 2020, at 8:06 PM, Bob Lunsford via groups.io <nocrud222=yahoo.com@groups.io> wrote:


Here's another item that may be of interest for you build-it-yourself hobbyists: An automatic antenna tuner. Costs $28 plus shipping for the kit...

Here are some specs for it:

Power supply range: 10 - 15 VDC
Max current : 450mA
Max working power: 100 watts
Max measured power: 150 watts
Minimum power for tuning start: 1 watt
Recommended maximum power while tuning not above 30 watts. (after tuning you can set 100 watts and work on this power)
Minimum measured power: 0.1 watt
Step for measurement on powers under 10 watts: 0.1 watt
Step for measurement on powers above 10 watts : 1 watt 
Power measurement accuracy : 10%
Maximum inductance set: 8.5 uH
Minimal step for setting inductance: 0.1 uH
Maximum installed capacity: 1870 pF
Minimal step for setting capacity: 10 pF






Russ@va3rr
 

I have one on order from Russia. Hope it doesn't get cancelled!


Gordon Gibby
 

I ordered one from a US source

On Aug 2, 2020, at 13:26, Russ@va3rr via groups.io <va3rr=yahoo.ca@groups.io> wrote:

I have one on order from Russia. Hope it doesn't get cancelled!



Guenter
 

The ATU 100 is an open source project and you can find all informations on GitHub.

https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards

It works fine with my uBitx after I modified cell 5 for a minimum power of 1W. Otherwise it will not always work on the higher bands.
For modifications in EEPROM cells you need Microchip PicKit3.


 

For a case I used:
    https://www.mouser.com/ProductDetail/854-BOX3-1455L-BK
and did my own bezel for the OLED display.  I'm not too happy with the
bezel yet.  The display should be closer to the front of the bezel to be more visible.

I included a picture (problem_area.jpg) showing a bad idea about to be brought to fruition.
The power trace is really close to the mounting holes which do not have the usual spacing
rings.  My lock washer shorted  across it.  I managed to kill a display and a regulator and burn
a few traces.  Maybe use tiny washers or nylon.  I used nylon.

  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/bezel_closeup.jpg
  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/exploded.jpg
  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/problem_area.jpg
  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/back.jpg

John
K6JDS

On 8/1/2020 7:06 PM, Bob Lunsford via groups.io wrote:
Here's another item that may be of interest for you build-it-yourself hobbyists: An automatic antenna tuner. Costs $28 plus shipping for the kit...

Here are some specs for it:

Power supply range: 10 - 15 VDC
Max current : 450mA
Max working power: 100 watts
Max measured power: 150 watts
Minimum power for tuning start: 1 watt
Recommended maximum power while tuning not above 30 watts. (after tuning you can set 100 watts and work on this power)
Minimum measured power: 0.1 watt
Step for measurement on powers under 10 watts: 0.1 watt
Step for measurement on powers above 10 watts : 1 watt 
Power measurement accuracy : 10%
Maximum inductance set: 8.5 uH
Minimal step for setting inductance: 0.1 uH
Maximum installed capacity: 1870 pF
Minimal step for setting capacity: 10 pF







Bob Lunsford
 

Good show, John. I like it. Very compact, too.

Bob   KK5R

On Sunday, August 2, 2020, 4:15:30 PM EDT, John Sutter <jds@...> wrote:


For a case I used:
    https://www.mouser.com/ProductDetail/854-BOX3-1455L-BK
and did my own bezel for the OLED display.  I'm not too happy with the
bezel yet.  The display should be closer to the front of the bezel to be more visible.

I included a picture (problem_area.jpg) showing a bad idea about to be brought to fruition.
The power trace is really close to the mounting holes which do not have the usual spacing
rings.  My lock washer shorted  across it.  I managed to kill a display and a regulator and burn
a few traces.  Maybe use tiny washers or nylon.  I used nylon.

  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/bezel_closeup.jpg
  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/exploded.jpg
  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/problem_area.jpg
  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/back.jpg

John
K6JDS

On 8/1/2020 7:06 PM, Bob Lunsford via groups.io wrote:
Here's another item that may be of interest for you build-it-yourself hobbyists: An automatic antenna tuner. Costs $28 plus shipping for the kit...

Here are some specs for it:

Power supply range: 10 - 15 VDC
Max current : 450mA
Max working power: 100 watts
Max measured power: 150 watts
Minimum power for tuning start: 1 watt
Recommended maximum power while tuning not above 30 watts. (after tuning you can set 100 watts and work on this power)
Minimum measured power: 0.1 watt
Step for measurement on powers under 10 watts: 0.1 watt
Step for measurement on powers above 10 watts : 1 watt 
Power measurement accuracy : 10%
Maximum inductance set: 8.5 uH
Minimal step for setting inductance: 0.1 uH
Maximum installed capacity: 1870 pF
Minimal step for setting capacity: 10 pF







Paul Parks
 

I've built two  - one for use remotely at the antenna and one built in the 3D printed case (files on GitHub).  I printed in PETG and drilled the antenna connector hole out for SO-239  - tight fit but works.

Vendor quality and delivery does vary.  Some have extra parts and some had a few easy to find parts missing (caps, transistors, wire).  One board had all of the SMD components soldered in place and one had none including the SMD PIC.

I am quite pleased with it.

Dave, W4VU  


 

Thanks.  One of these days I'll get the power switch.  I've just been waiting
to place a bigger order.

One other thing to watch out for is that some of the PCBs out there come with an expanded button
header for all three buttons.  Most only have a header for a single button, so you'll need to run wires
directly from the PCB.  I was lucky and got the one with the expanded header which made life easier.

John
K6JDS


On 8/2/2020 4:58 PM, Bob Lunsford via groups.io wrote:
Good show, John. I like it. Very compact, too.

Bob   KK5R

On Sunday, August 2, 2020, 4:15:30 PM EDT, John Sutter <jds@...> wrote:


For a case I used:
    https://www.mouser.com/ProductDetail/854-BOX3-1455L-BK
and did my own bezel for the OLED display.  I'm not too happy with the
bezel yet.  The display should be closer to the front of the bezel to be more visible.

I included a picture (problem_area.jpg) showing a bad idea about to be brought to fruition.
The power trace is really close to the mounting holes which do not have the usual spacing
rings.  My lock washer shorted  across it.  I managed to kill a display and a regulator and burn
a few traces.  Maybe use tiny washers or nylon.  I used nylon.

  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/bezel_closeup.jpg
  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/exploded.jpg
  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/problem_area.jpg
  http://www.sutters.com/AmateurRadio/N7DDC_ATU-100/back.jpg

John
K6JDS

On 8/1/2020 7:06 PM, Bob Lunsford via groups.io wrote:
Here's another item that may be of interest for you build-it-yourself hobbyists: An automatic antenna tuner. Costs $28 plus shipping for the kit...

Here are some specs for it:

Power supply range: 10 - 15 VDC
Max current : 450mA
Max working power: 100 watts
Max measured power: 150 watts
Minimum power for tuning start: 1 watt
Recommended maximum power while tuning not above 30 watts. (after tuning you can set 100 watts and work on this power)
Minimum measured power: 0.1 watt
Step for measurement on powers under 10 watts: 0.1 watt
Step for measurement on powers above 10 watts : 1 watt 
Power measurement accuracy : 10%
Maximum inductance set: 8.5 uH
Minimal step for setting inductance: 0.1 uH
Maximum installed capacity: 1870 pF
Minimal step for setting capacity: 10 pF








Dave Bescoby
 


Just to add, I managed to shoehorn one of these into my uBitx v5 case for portable use and it seems to work well. As mentioned, very configurable, including LED SWR indication if required. Displays run on I2C serial connection and so should be possible to integrate with main uBitx display, which would be a nice touch.

All best wishes,

Dave


Sent from ProtonMail Mobile


On Sun, Aug 2, 2020 at 20:17, Guenter DF1KU via groups.io <gfs1415@...> wrote:
The ATU 100 is an open source project and you can find all informations on GitHub.

https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards

It works fine with my uBitx after I modified cell 5 for a minimum power of 1W. Otherwise it will not always work on the higher bands.
For modifications in EEPROM cells you need Microchip PicKit3.



mm0bef@...
 

I have been keeping an eye on these for some time but was not sure about performance. After seeing these posts i have ordered one to put in my V5 case. Awaiting agc kit also.

Best regards

Brian_____MM0BEF


Aaron K5ATG
 

Mine came in the mail today, I have yet to find any instructions for it but the search will continue. 
--
'72
Aaron Scott
QRPARCI# 16443
GQRP# 16389
4SQRP # 1080


Shirley Dulcey KE1L
 

I don't know what kind of automatic ATU you got. If it's one of the kits from China it's probably based on the N7DDC design, which is documented at https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards


On Mon, Sep 21, 2020 at 10:33 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io> wrote:
Mine came in the mail today, I have yet to find any instructions for it but the search will continue. 
--
'72
Aaron Scott
QRPARCI# 16443
GQRP# 16389
4SQRP # 1080


Ashhar Farhan
 

At 28 dollars, this looks like a steal. It would be best to rewrite the code for arduino for this group. It should be a simple task. I have used a similar setup earlier.
There were a few challenges:
1. The relays have 300 ohms coils. Together, all of them can consume over 12/30 = 350ma of current at all times. To save on this, you need latching relays. With them, the current can drop to less than a milliamp.
2. The relays must be of top quality as they will chatter quite a bit.
The way out is a little more elaborate:
A. Use a variable cap with a servo. Servos are cheap, capacitors are not.
B. Use high voltage FETs to short the inductors. 

On Tue 22 Sep, 2020, 9:06 AM Shirley Dulcey KE1L, <mark@...> wrote:
I don't know what kind of automatic ATU you got. If it's one of the kits from China it's probably based on the N7DDC design, which is documented at https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards

On Mon, Sep 21, 2020 at 10:33 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io> wrote:
Mine came in the mail today, I have yet to find any instructions for it but the search will continue. 
--
'72
Aaron Scott
QRPARCI# 16443
GQRP# 16389
4SQRP # 1080


Shirley Dulcey KE1L
 

Unfortunately, using latching relays would at least double the price of the kit. I haven't found any sources of inexpensive ones.


On Mon, Sep 21, 2020 at 11:46 PM Ashhar Farhan <farhanbox@...> wrote:
At 28 dollars, this looks like a steal. It would be best to rewrite the code for arduino for this group. It should be a simple task. I have used a similar setup earlier.
There were a few challenges:
1. The relays have 300 ohms coils. Together, all of them can consume over 12/30 = 350ma of current at all times. To save on this, you need latching relays. With them, the current can drop to less than a milliamp.
2. The relays must be of top quality as they will chatter quite a bit.
The way out is a little more elaborate:
A. Use a variable cap with a servo. Servos are cheap, capacitors are not.
B. Use high voltage FETs to short the inductors. 

On Tue 22 Sep, 2020, 9:06 AM Shirley Dulcey KE1L, <mark@...> wrote:
I don't know what kind of automatic ATU you got. If it's one of the kits from China it's probably based on the N7DDC design, which is documented at https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards

On Mon, Sep 21, 2020 at 10:33 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io> wrote:
Mine came in the mail today, I have yet to find any instructions for it but the search will continue. 
--
'72
Aaron Scott
QRPARCI# 16443
GQRP# 16389
4SQRP # 1080


Dave Dixon
 

Ive been using my auto atu from china since they first came out paid £38.00 and am very impressed with it tuned 4 of my wire aerials with no problems and getting good reports on various bands on my v3 bitx,you can hardly hear the relays chattering as they search for unity.Highly recommended.Dave G0AYD FISTS 15892.CWOPS 2159.

On Tue, 22 Sep 2020 at 03:33, Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io> wrote:
Mine came in the mail today, I have yet to find any instructions for it but the search will continue. 
--
'72
Aaron Scott
QRPARCI# 16443
GQRP# 16389
4SQRP # 1080