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ATU-100 Current Draw?

CBJessee-N4SRN
 

What would be the current draw for the ATU-100 (the firmware V3.2 model with Tune, Auto, Bypass and 4-line screen) in idle? I read that the ATU-100 does not have latching relays so it must be powered on to retain the tuning.

BRET/N4SRN
 

Hi Bret, The supply current of the ATU-100 is dominated by the number of relays that are activated and the unit does need to be powered to retain the tuning.

Each relay has a coil resistance of approximately 750 Ohms.
The measured current consumption of the PIC and OLED display is approximately 13 mA.
The voltage drop across the protection diode on the supply rail is approximately 0.7V.
Therefore the estimated supply current with respect to the number of active relays is shown below for 12V and 13.8V.


At a supply voltage of 13.8 V, the measured current of my ATU-100 is 0.27 A. This does drop slightly over time since the relay coil resistance will tend to increase.
Using the default firmware, after reset only one of the relays is powered (C-Select), which is set to output.

Typically the seller specifies a maximum supply current of 0.45A, which will be the worst case and based on the minimum value of the relay coil resistance.
73, Dave
CBJessee-N4SRN
 

Thanks, Dave. So, the ATU-100 may not be the best option for QRP radio operation on battery power, although the current draw may vary considerably based on antenna and configuration.

Are there other small/lightweight ATUs with latching relays that might be a better option?

Bret/N4SRN
 

Hi Bret, There is a QRP version by the same designer called the ATU-10 that uses latching relays.


There are other QRP tuners that may be suitable for your needs.
73, Dave
 

The Elecraft T1 has a low power QRP tuner:

>T
the LDG Z-11 Prp has latching relays:

<>

I have both tuners. Both product lines may be hard to find. Check the Ham Radio Distributors for LDG tuners.

Note many QRP manual tuners today use polyvaricon capacitors. Wes Haywood, W7ZOI, one of my favorite tech writers, studied the Q of various capacitors and found the Q of polyvaricon capacitors to be very low, therefore they have a high loss. I would not use high loss capacitors for QRP operation.

<>

The problem today is that new mechanical variable capacitors are expensive. The best place to find variable capacitors is at ham fests today.

The only QRP tuner that I know of that does not use polyvaricon tuners is the MFJ-971 tuner

<>

I had this tuner and it did a good job. MFJ products have a reputation of poor quality. I checked my tuner and the assembly and all solder joints looked fine.

Does anyone else know of QRP tuners or tuner kits that does not use polyvaricon capacitors?

Mike N2MS


On 04/24/2023 7:31 AM CBJessee-N4SRN <cbjesseenh@...> wrote:


Thanks, Dave. So, the ATU-100 may not be the best option for QRP radio operation on battery power, although the current draw may vary considerably based on antenna and configuration.

Are there other small/lightweight ATUs with latching relays that might be a better option?

Bret/N4SRN
 

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Bret

Take a look at the ATU-100's little brother, the ATU-10. Specifically designed for the type of operation you have in mind, including latching relays.

Bill VK7MX

On 24/04/2023 9:31 pm, CBJessee-N4SRN wrote:

Thanks, Dave. So, the ATU-100 may not be the best option for QRP radio operation on battery power, although the current draw may vary considerably based on antenna and configuration.

Are there other small/lightweight ATUs with latching relays that might be a better option?

Bret/N4SRN

 

Does anyone have an exrta pcb for the atu-10 that i might buy?

thanks dave k7da

Take a look at the ATU-100's little brother, the ATU-10. Specifically designed for the type of operation you have in mind, including latching relays.

Bill VK7MX

_._,_._,_
 

Dave I have a couple of ATU-10 PCB's here.

They use 0603 parts in the main as per N7DDC's board but the two Micros are for the larger footprint types. ie easier to find and solder.

Glenn
vk3pe
 

开云体育

Hi glen

how did you stay in the hospital come out.? hope all is well.

How much are you asking and what is the postage to the usa.

dave k7da

On 4/26/2023 12:57 AM, Glenn wrote:

Dave I have a couple of ATU-10 PCB's here.

They use 0603 parts in the main as per N7DDC's board but the two Micros are for the larger footprint types. ie easier to find and solder.

Glenn
vk3pe
 

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Hi Dave
OK in the end. 2 weeks in trying to find the problem. Turned out my blood pressure dropped to about half from lying down or sitting to standing. A change of BP medicine has almost eliminated it. While there I came down with novavirus which kept me confined to the room for a week....diarrhea in other words. Not pleasant. And my birthday right in the middle of my stay.?

Dave I will send the pcb for free. It will be in a envelope which is not strictly legal these days.....must be documents only. I put the pcb into a cutout in a bit of cardboard which seems to work.
Legal means is almost 5 times the cost plus customs form etc.? Now i have to submit 4 copies. Apparently they send that forward to usa so the package can be more quickly processed compared to the single copy before.

Mind you when I receive a parcel it only ever has 1 copy like the old way. Weird.

Give me your address and I will posta asap.? Probably Monday.

Glenn?



Sent from my Samsung Galaxy S7 smartphone.


-------- Original message --------
From: k7da <k7da@...>
Date: 27/4/23 12:33 am (GMT+10:00)
Subject: Re: [ATU100] ATU-100 Current Draw?

Hi glen

how did you stay in the hospital come out.? hope all is well.

How much are you asking and what is the postage to the usa.

dave k7da

On 4/26/2023 12:57 AM, Glenn wrote:
Dave I have a couple of ATU-10 PCB's here.

They use 0603 parts in the main as per N7DDC's board but the two Micros are for the larger footprint types. ie easier to find and solder.

Glenn
vk3pe
 

开云体育

Am i to assume that you are all better and back home.? The only thing good about a hospital it you get to watch the girls and do nothing.? although some of us find that to be a bore.

address is as follows.

Dave Alexander

620 3rd ave

Aberdeen,? WA 98520

and I do thank you.

dave k7da


On 4/27/2023 3:30 AM, Glenn wrote:

Hi Dave
OK in the end. 2 weeks in trying to find the problem. Turned out my blood pressure dropped to about half from lying down or sitting to standing. A change of BP medicine has almost eliminated it. While there I came down with novavirus which kept me confined to the room for a week....diarrhea in other words. Not pleasant. And my birthday right in the middle of my stay.?

Dave I will send the pcb for free. It will be in a envelope which is not strictly legal these days.....must be documents only. I put the pcb into a cutout in a bit of cardboard which seems to work.
Legal means is almost 5 times the cost plus customs form etc.? Now i have to submit 4 copies. Apparently they send that forward to usa so the package can be more quickly processed compared to the single copy before.

Mind you when I receive a parcel it only ever has 1 copy like the old way. Weird.

Give me your address and I will posta asap.? Probably Monday.

Glenn?



Sent from my Samsung Galaxy S7 smartphone.


-------- Original message --------
From: k7da <k7da@...>
Date: 27/4/23 12:33 am (GMT+10:00)
Subject: Re: [ATU100] ATU-100 Current Draw?

Hi glen

how did you stay in the hospital come out.? hope all is well.

How much are you asking and what is the postage to the usa.

dave k7da

On 4/26/2023 12:57 AM, Glenn wrote:
Dave I have a couple of ATU-10 PCB's here.

They use 0603 parts in the main as per N7DDC's board but the two Micros are for the larger footprint types. ie easier to find and solder.

Glenn
vk3pe
 

开云体育

Hi Dave?
Yes after two weeks there I came home. Basically the change of BP medicine has fixed. About 95% better now. And yes it was very boring. Most nurses here by the way these days are Indian or Sri Lankan.

So have been home about 4 weeks now.

OK on address.? Thanks.

Glenn?



Sent from my Samsung Galaxy S7 smartphone.


-------- Original message --------
From: k7da <k7da@...>
Date: 28/4/23 12:35 pm (GMT+10:00)
Subject: Re: [ATU100] ATU-100 Current Draw?

Am i to assume that you are all better and back home.? The only thing good about a hospital it you get to watch the girls and do nothing.? although some of us find that to be a bore.

address is as follows.

Dave Alexander

620 3rd ave

Aberdeen,? WA 98520

and I do thank you.

dave k7da


On 4/27/2023 3:30 AM, Glenn wrote:
Hi Dave
OK in the end. 2 weeks in trying to find the problem. Turned out my blood pressure dropped to about half from lying down or sitting to standing. A change of BP medicine has almost eliminated it. While there I came down with novavirus which kept me confined to the room for a week....diarrhea in other words. Not pleasant. And my birthday right in the middle of my stay.?

Dave I will send the pcb for free. It will be in a envelope which is not strictly legal these days.....must be documents only. I put the pcb into a cutout in a bit of cardboard which seems to work.
Legal means is almost 5 times the cost plus customs form etc.? Now i have to submit 4 copies. Apparently they send that forward to usa so the package can be more quickly processed compared to the single copy before.

Mind you when I receive a parcel it only ever has 1 copy like the old way. Weird.

Give me your address and I will posta asap.? Probably Monday.

Glenn?



Sent from my Samsung Galaxy S7 smartphone.


-------- Original message --------
From: k7da <k7da@...>
Date: 27/4/23 12:33 am (GMT+10:00)
Subject: Re: [ATU100] ATU-100 Current Draw?

Hi glen

how did you stay in the hospital come out.? hope all is well.

How much are you asking and what is the postage to the usa.

dave k7da

On 4/26/2023 12:57 AM, Glenn wrote:
Dave I have a couple of ATU-10 PCB's here.

They use 0603 parts in the main as per N7DDC's board but the two Micros are for the larger footprint types. ie easier to find and solder.

Glenn
vk3pe

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