Thetis Tune Drive Attenuation

[Jason Petrovffsky]

I am wondering if the Tune Drive Attenuation is Software driven in Thetis or is it a hardware limitation of the HL2. I would like to find a way to attenuate my Tune Drive lower then the max setting of -16.5dB. On 20 meters and below my amplifier still puts out over 100 watts on -16.5dB and over loads my MFJ998 Auto tuner. I temporarily fix this by putting a 3dB attenuator in line of the coax between HL2 and my PA when I press TUN but would like to see if the software is modifiable to produce a more attenuated drive signal. 

[Rick Langford (N8SDR)]

See the pic below, as it sounds like your not using the independent tuner slider option

reason I say this is  a min setting using the tune slider separated from Drive slider option, I run a SS with NO PADDING and around 29-32 DB gain

using the min setting on the tune slider I can minimize that to about 7=10 watts

a slight bump and I'm well over that

the intendant tune slider has much more control

As far as I know Reid has down about what can be done with Thetis on the Tune slider, there may be a way or little wiggle room to make another adjustment on the driver slider for a little more control , but I think that will also involve using a option that ties in with the MIC gain and or VAC gain to actually reduce audio gain thus lower Output gain as well

[Jason Petrovffsky]

Thank you for your response. I do have the slider enabled and set it to the max -16dB setting. The strange thing is I seem to get varying levels of output, especially on 20 meter and below. Sometime my PA puts out 10-20 watts and then sometime it is well over 100. Then sometimes I did not get any drive signal from the HL2. I can press tun 3 times in a row and get different results. When HL2 puts out nothing on tune I usually power cycle it and seems to fix it for a while.. I have re-flashed the gateware to current. Can you point me in the right direction for adjusting the audio gain on Tune. Your well written tutorials have been invaluable, I remember when I first got the HL2 a few years ago I fumbled around a lot to figure it out. Thanks again.

[Rick Langford]

What what of thetis 

And who's Ritchie or Reid's version 

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From: herme...@googlegroups.com <herme...@googlegroups.com> on behalf of Jason Petrovffsky <jasonpet...@gmail.com>
Sent: Monday, February 10, 2025 10:09:26 AM
To: Hermes-Lite <herme...@googlegroups.com>
Subject: Re: Thetis Tune Drive Attenuation

 

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[Jason Petrovffsky]

I did not realize there was two versions I use the MI0BOT

[Rick Langford]

That the correct version 

I asked because some use the other and it's incorrect for the Hermes Lite 2

There is something else going on I suspect with your setup it's very repeatable as in consistent with as both my Hermes and friends who run them.

Do make sure you have the ignore SWR box checked in thetis for the HL2 as that can cause issues.

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From: herme...@googlegroups.com <herme...@googlegroups.com> on behalf of Jason Petrovffsky <jasonpet...@gmail.com>

Sent: Monday, February 10, 2025 11:40:42 AM

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[Jason Petrovffsky]

Thank you. I believe the SWR protection was one of my problems.  I did the AH4 tuner modification and the HL2 directly initiates the tuner. I have done more testing and realized that when I first press TUN I here the bypass relay click, I get a spike of power on the tuner's meter. Then about a second of no output then a steady output. I think this delay is just long enough to make the MFJ-998 auto tuner think there is not enough power to tune. It stops and throws an "Increase Power" Error before that steady output begins. I'm wondering if this is latency in transmit chain or normal. Is there any setting that would create a delay on the transmit tone? I did the AH4 tuner modification and the HL2 directly initiates the tuner. I appreciate your guidance.

[Reid Campbell]

Hi Jason,

AFAIK, the drop in carrier is part of the AH4 protocol and is initiated by the FPGA. I'm not sure you are going down the right route, as you are trying to get it to work with the MFJ-998.

The I/O Board was designed for interfaces like this and the I2C protocol has a AH4 like protocol which the HL2 version of Thetis will use. Tune using this I2C protocol is achieved by pressing the Ctrl key, while clicking the TUN button.

Have a look at the specification for the I/O Board: https://github.com/jimahlstrom/HL2IOBoard

Cheers

Reid
GI8TME/MI0BOT   

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[Robert Benedict]

Jason

  I use my HL2 with a HardRock 50 amp and an MFJ993B remote tuner. I also see varying levels of output on initial tune. 

The power the amp puts out on tune will depend on the impedance the amp sees when tuning starts. With the same drive the amp will put out much more power to an initial low impedance. So at initial tune the power out will vary depending antenna impedance and the last tuner solution.

   Bob  KD8CGH