+12V output when TX?

Gord-VA7GP

Hi, Flex'ers:

I seek a +12V signal when I key my '6400. I want to use this for some switching; the manual seems to say all the TX1-3 are pull-to-ground and would require a pull-up resistor...?

Is there some port/pin/jack which will source +12V at 10mA upon transmit? Or, where would I find and apply a pull-up to +12V for a TX1 signal that does what I need?

(for the truly curious: I operate my TS-850 in this manner, with the +12V TX being some 10ms faster than using the T/R relay. This +12V TX signal goes into a buffer/inverter box containing a Solid-State-Relay (SSR) which in turn triggers the open-frame relay in my Collins 30S-1 amp. The '6400 TX1 output is not directly compatible with the amp's 12V relay: the current is high and un-specified, and the inductive-kick upon opening is at least 100V... my buffer/inverter box deals with all this).

Mike-VA3MW

You can tie an event based on PTT.

Section 35.2.2. 73

KD0RC

You are correct, the TX outputs take a positive voltage (up to 40 V) to ground at transmit time. The manual warns about inductive kickback and transients potentially damaging the radio.

I think you can use the same buffer box that you have, but you would need to invert the TX 1, TX2 or TX 3 signal going into it. An NPN transistor and current limiting resistor would be a simple solution; an opto-isolator is probably a better choice. You would need to verify the voltage and current requirements of the buffer box to know what devices could be safely used.

Gord-VA7GP

Thanks for the confirmation/reply…

the elegance of my existing buffer box: no power! The SSR gets enough trigger-power from my TS-850 +12v

your suggestion is the same that I thought of, but I had hopes for a source of +12v from my 6400 if it turned out I could not avoid power

73 and tnx!

Mike-VA3MW

Why not use the USB device on the back of the radio to drive an external relay board? This is what it is there for.

https://www.flexradio.com/documentation/usb-cable-interface-guide-pdf/

https://www.amazon.com/SainSmart-Eight-Channel-Relay-Automation/dp/B0093Y89DE/ref%3Dsr_1_3

KD0RC

Hi Mike, the bit cables switch based on band. He is trying to switch based on PTT status. So unless there is a bit tied to PTT, I think he needs a little 12 V relay driver for one of the TX ports.

Gord-VA7GP

Thanks for the suggestions, guys. In-depth suggestions.

These suggestions - and the reality of the situation - paints me into a corner, where I'll have to adapt...

For sure - I am NOT going to use a relay. Adding 10ms to the TX-time is a non-starter, to say nothing of the fact that when I play with older (25+ years) radio, relays are among the most-problematic...

And while I dislike having to add a source-of-power to get +12V in one manner or the other, I am turning to the reality that this is probably what I'll have to do...

Mike-VA3MW

At the moment, that is the only solution that I have for you and this is the reason these hardware options are available.

If your concern is sending RF before your downstream devices are ready for transmit, the radio has a built-in sequencer to allow for RF to be delayed until devices are fully engaged.

This is why on the BIT cables you can specify a delay time if required.

As well, there is an overall Transmit Delay function that ensures that no RF is sent until that time expires. This page mentions the earlier models but the functions are available on all FlexRadio 6000 series of radios. Setting TX Delay to 20 ms is a good starting point.

The BIT cables are used extensively by Microwave and EME users who use them to switch transverters and preamps in and out of the transmit path. They have been proven by many other operators to be incredibly reliable but we do urge you to do your own testing as each station is unique with different priorities.

In the FlexRadio networking world, the move to using TCP/IP to control amplifiers and tuners has allowed us to make sure down stream devices are ready for TX before going into TX. As an example, if a user is using a PGXL and a TGXL at the same time, when you put the radio into transmit the radio then checks with both the PGXL and the TGXL to ensure they are 'ok' to go to TX before sending RF. TCP/IP being faster than a series of mechanical relays.

KD0RC

Thanks for that Mike, I missed the part about mapping PTT. Wow... I can see lots of possibilities with that functionality.

Mike-VA3MW

Yes, it is pretty powerful.

And, if you need speed, you could go to an FTDI Parallel Bit cable and just switch transistors or optoisolator with your own design.

https://www.flexradio.com/products/usb-to-parallel-adapter-for-the-flex-6000-series/

Gord-VA7GP

To wrap this up for the bystanders / onlookers / Googlers and participants:

I've decided that integrating my '6400 is my highest priority, and my legacy gear will be supported (but not prioritized).

I'll re-design my amp-interface box, with short-to-GND TX taking priority. I'll hold my nose as I succumb to the need to add +12V power to my interface box. Having a TX signal of +12V will also be supported.

Sure, Hamgadgets makes their UKA 3+ which will do what I want done (and also RBI-1), and there is the venerable ARB-704. ARRL Handbook also provides ideas. For some, that may be the right answer. But I opt for a Hammond box, an optocoupler, a handful of diodes, a couple of FETs and resistors, some status LEDs and top-notch connectors + stainless hardware. No relays. And while I'm at it, I'll probably diode-OR a couple of additional inputs so I can add to the radio collection 😁 Four separate exciters should be enough for any ham.... right 🤣