XVTR TX output active when using 28MHz

G3ZQH
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XVTR TX output active when using 28MHz

Postby G3ZQH » Fri Feb 11, 2022 6:00 pm

I recently changed my 28/144 MHz transverter installation so that it could be left permanently on in periods when I am switching between HF/VHF activity. This is mainly to help with frequency stability in the transverter but also for convenience. I was very surprised to notice RF out on 144MHz when I was using 28MHz band on my 200D. Checking, I found that the XVTR TX output (20dBm/100 mW max) was active when TX on 28MHz and driving my 144MHz PA to give full 250W output! I would expect when in HF mode then there would be no RF to the XVTR output. This may have been present all the time but I never noticed it before.

So, does anyone else see this? It could be a long-standing bug or possibly something introduced by some of the recent changes to Thetis? Previously I know there was a problem (now fixed) with the main PA TXing when in XVTR mode. What I see is the reverse of this where the XVTR TX is active in HF mode.

200D, Thetis 2.8.11 v21k8 (MW0LGE), Protocol 2 v1.9 pre4.

73 Dave G3ZQH
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w-u-2-o
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Re: XVTR TX output active when using 28MHz

Postby w-u-2-o » Fri Feb 11, 2022 7:47 pm

If you look at the schematics for the 200D:

viewtopic.php?f=35&t=2338

you will see that the hardware directly connects the TX output of the Orion board to both the amp input on the PA board and the transverter output connector. There is no way to sever this connection via software or firmware internally.

One possible solution would be to put a coaxial switch between the the transverter output and the transverter that would break the connection during HF operations. You could potentially control this switch automatically using the OC output feature of the ANAN hardware.
G3ZQH
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Re: XVTR TX output active when using 28MHz

Postby G3ZQH » Fri Feb 11, 2022 8:57 pm

Thanks Scott- you are exactly right about this! I should have checked the schematic first. For now I'll just make sure to turn the transverter/PA OFF when I'm on HF. I have several small small relays which should be suitable to switch out the XVTR TX line . I'm using most of the OC controls but think I have one spare which should do the job.
73 Dave G3ZQH
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FM5GB
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Re: XVTR TX output active when using 28MHz

Postby FM5GB » Sat Feb 26, 2022 12:51 pm

Hi Dave,

On my 200D (as on your's most probably) there is HF power on the transverter TX output when transmitting on ANY HF band. I had to put a 28 MHz band pass filter on the HF input of my home made transverter to correct this mess somewhat. This is why I'm considering more and more to abandon my Anan.

73s Phil FM5GB
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w-u-2-o
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Re: XVTR TX output active when using 28MHz

Postby w-u-2-o » Sat Feb 26, 2022 2:32 pm

Please abandon it at my house ;)
dk8nd
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Re: XVTR TX output active when using 28MHz

Postby dk8nd » Sat Apr 23, 2022 2:36 pm

Dear OM,
please have a look to the block schematic of the ANAN 200 or in my case 8000DLE. The antenna outputs Ant1...Ant3 are T/R-output connectors for the PA and for RX1. RX2 has an own connector RX2 Ant, as well as TVTR TX.

Use RX2_Ant as Receiver input for Your tansverter and use XVTR TX as exiter for transmitting with transverter. Please note: With Thetis control program RX2 is just a "second class receiver". Tuning it for narrow band cw is more difficult than tuning RX1 for the same mode. Though both receivers are according to block schematic equal in hardware, by using Thetis control program RX2 cannot be controlled straight forward as RX1. The marking on the outlets at the back panel of the ANAN 8000DLE may differ from the marking in the block schematic, . Used handbook: ANAN-8000DLE Users Gui8de, 15 March 2017, Block Schematic on page 10.
There is now other way in beeing qrv on HF and LF/MF or VHF with transverters.

73,
Hans-Albrecht
DK8ND
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w-u-2-o
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Re: XVTR TX output active when using 28MHz

Postby w-u-2-o » Sat Apr 23, 2022 4:37 pm

dk8nd wrote:Please note: With Thetis control program RX2 is just a "second class receiver". Tuning it for narrow band cw is more difficult than tuning RX1 for the same mode. Though both receivers are according to block schematic equal in hardware, by using Thetis control program RX2 cannot be controlled straight forward as RX1.

Why do you write that, Hans? I can control RX2 exactly the same as I do RX1. There is not a separate RIT or CW APF, but other than that they are identical.
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w-u-2-o
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Re: XVTR TX output active when using 28MHz

Postby w-u-2-o » Sat Apr 30, 2022 3:12 pm

FM5GB wrote:Hi Dave,

On my 200D (as on your's most probably) there is HF power on the transverter TX output when transmitting on ANY HF band. I had to put a 28 MHz band pass filter on the HF input of my home made transverter to correct this mess somewhat. This is why I'm considering more and more to abandon my Anan.

73s Phil FM5GB

Phil,

Revisiting this given your recent negative comment in another topic: why not simply add an external switch on the transverter TX output? It could be automatically switched as required using an OC output, programmed as required in Setup > General > OC Control.

73,

Scott

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