external directional coupler

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JO

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Feb 8, 2025, 5:17:23 AM2/8/25
to Hermes-Lite
external directional coupler
Is there any possibility of connecting an external directional coupler from a 600W PA to a Hermes lite 2, after setting the cross meter to 600W and having a reading for this power?
thetis600w.jpg

Lukasz Olszewski

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Feb 8, 2025, 10:16:12 AM2/8/25
to JO, Hermes-Lite
I too am interested in the answer. There is an ADC on the raspberry pi pico in the IO board that maybe can be utilised, but I don't know if there is any software that supports it. Or if it has to be written by oneself.

73, Łukasz 

On Sat, 8 Feb 2025, 11:17 JO, <ct2...@gmail.com> wrote:
external directional coupler
Is there any possibility of connecting an external directional coupler from a 600W PA to a Hermes lite 2, after setting the cross meter to 600W and having a reading for this power?

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Ed Grafton

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Feb 8, 2025, 12:13:40 PM2/8/25
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If you read the schematic & description of the boards, you will find where you can run a 5VDC signal for FOR/REF power, then calibrate Thetis to read your amplifier's output.

Ed

DL1YCF

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Feb 8, 2025, 4:15:47 PM2/8/25
to Lukasz Olszewski, herme...@googlegroups.com
If you look at the specification of the IO board, you will find
that there are three ADC values which can be read from registers
25/26, 27/28, and 29/30.

So the SDR host software in principle can read them, but
if you want this be taken as fwd/ref, you better get the
source code of the SDR host software (e.g. Thetis) and
build this in (if it is not yet there).
> To view this discussion visit https://groups.google.com/d/msgid/hermes-lite/CACwB4R6sx28sPvqJZRo9iqCdzbAxv%3Dy2D65GByPnQktHHqLXAw%40mail.gmail.com.

Ed Grafton

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Feb 9, 2025, 7:33:32 AM2/9/25
to Hermes-Lite
FInd P9 on this schematic of the N2ADR filter board & read the notes. No need for the IO board for what you want.

Ed

Lukasz Olszewski

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Feb 9, 2025, 8:38:07 AM2/9/25
to Ed Grafton, Hermes-Lite


On Sun, 9 Feb 2025, 13:33 Ed Grafton, <yankn...@gmail.com> wrote:
FInd P9 on this schematic of the N2ADR filter board & read the notes. No need for the IO board for what you want.

Ed
Thanks.

I wonder if there is some way to have your cake and eat it it too in this situation ... 

I mean have a switchable way to get normal swr reading and when using the amp get external input. I can imagine how to do it with some changes, but maybe there is a simple way.

I often use my HL2 without an amp (mainly for testing antennas with wspr).

73, Łukasz 


Ed Grafton

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Feb 9, 2025, 1:01:04 PM2/9/25
to Hermes-Lite
I would consider using a relay from stock to high power inputs.

Ed

John Williams

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Feb 9, 2025, 1:13:24 PM2/9/25
to Hermes-Lite
What I did is leave the amp inline and just shut it off, thus reading the 0-5W output from the external directional coupler as it passes thru the unpowered amp T/R relay. Was accurate enough for my needs. 

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