Re: 100W Automatic Antenna Tuner...

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

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

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