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Author Topic: RF sensing TE system amplifier (1454GRH, 144-148 MHZ, 60-80W in and 350-40  (Read 126 times)

KO4ENU

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I am trying to disable the RF sensing on my TE system amplifier (1454GRH, 144-148 MHZ, 60-80W in and 350-400 out) and hard key the amplifier using pin 2 and 6 in the older style 7 pin socket.

I also read that in conjunction with the connecting the two pins I would need to defeat the RF sensing circuit. The RF sensing circuit can be disconnected from the circuit by lifting the leg of the capacitor that is connected directly to the coax RF input line. I did this by desoldering the leg and there was still RF sensing so while I had the capacitor leg up I also grounded it to the chassis to see if that would work. Both times there was an amplified RF output when I keyed the radio (ICOM 9700) and allowed RF into the amp. The amplifier sensed it and linearly amplified the signal per the inline watt meter.


How do I get amp to quit RF sensing so that my sequencer can hard key it at the predetermined interval?

I am wondering if I even need to lift that leg up or just connect pin two to the sequencer and pin 6 also to the ground of the sequencer (SSB 2004B).

I am attempting digital EME with JT 65B so the amplifier must be hard keyed to be connected to a SSB 2004 B sequencer and my SP 200 mast mounted pre amplifier .


Pin out in the back amp


Pin 1 is FM/SSB mode selection. External control will override front panel switch if it is placed in CW-SSB position and this pin is grounded.
Pin 2 is the PTT line. (Ground to TX. This will override the RF sensed default PTT)
Pin 3 is +12.5 VDC typ. up to 1A maximum accessory power.
Pin 4 No connection
Pin 5 is Remote Control operation. When ungrounded the PA cannot be activated. Cut internal grounding wire to activate this.
Pin 6 is Ground.
Pin 7 is LED illumination control. When ungrounded the front panel LED except for RF LED are not operative. Cut internal grounding wire to activate this.

In most cases, you just need to wire your transceiver PTT to pin 2 and pin 6 ground.

Thank you for any assistance and support by answering questions.

Steve
KO4ENU
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W9IQ

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Steve,

I haven't looked at the schematic but try grounding the lifted capacitor leg instead of leaving it floating.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KO4ENU

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Glen, thank you for responding and I did ground the lifted leg to the chassis and it was RF sensing. I just cannot figure it out...


Steve
KO4ENU
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W9IQ

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Steve,

Now I am back in the office and so I could look at my TE references. I believe you need to break the connection between pins 5 and 6 on the accessory connector to disable RF sensing and then assert PTT on pin 2 - it needs to be grounded to transmit (pin 6 is available for the ground reference). Have you already tried this?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KO4ENU

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Glenn, broke the connection between pin 5 and 6 on the accessory connector and it was still 50 watt in 200 watts out. As pin 5 was disconnected,  I decided to  connected pin 2 to ground and it was still 50 in 200 out. I then re soldered pin 5 back on to the accessory connector and again grounded pin2 to ground 50 watts in and 200 watts out.

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