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USB 8 Channel Relay Board Setup for Transverters and Bit Menu Setup and TX delay

KM0T Member ✭✭
edited August 2019 in New Ideas
Some folks have asked how I set up my USB bit cable relay board and delays.  Here is a brief description of how I implemented the 8 channel relay board for 222 and 432 MHz transverters, amplifiers and mast mounted preamps.

(Back Room Mess...)

Radio:  Flex 6600 – utilize transverter port A and B

Transverters:  Kuhne 222 and 432 MHz - split IF

Power Amps:  W6PQL 1KW LDMOS linears for 222 and 432

Preamp system:  DEMI preamps with DEMI DTR high power - high isolation transfer relays

Relay Board:  SainSmart USB Eight Channel Relay Board for Automation (via Amazon)

Got to thinking of all the needs of sequencing and control of all components.  The potential to damage the preamps and transverter front ends from hot switching makes you think twice when the equipment is expensive and a pain to get at if replacement is needed. 

Looking at traditional sequencer boards was a start, but they have limited adjustability.  I also wanted to be able to turn the preamps on and off to determine their effectiveness.   I also wanted to be able to disable the amplifiers and run just the transverter without having to go to the back room to hit the enable switch.  I didn’t really want to wire a whole bunch of remote switches, etc. to get flexibility with traditional sequencers.

Messing around with the SainSmart board for a while revealed a solution that effectively does it all.  Credit to Flex Radio and programming the USB menus!  Below is the block diagram for the board layout wiring to components.



(above with preamp power enabled for 222 and 432 - note the LED next to R1 and R5 - active relay)

In addition, here is screen shot of the USB bit cable setup menu in SmartSDR.


Here are some notes on why things are setup as they are:

Utilizing the Flex-6600 as a dual transverter driver.  When on HF, one does not need to power the transverter preamps.  So the first relay for each band (the ones labeled “enable” relays – Relay 1 and 5 on the board – Bit Pin 0 and 4 USB Menu) allow VCC 13.8V to be available to the preamps based on Frequency Range.  So if your on HF, these relays are not active and do not allow the VCC to be available to the preamps.  Power off state being the NC contacts with no connection, no VCC allowed to make it to the next relay.  Move a slice to the transveter band, then the relay is active and allows VCC to the next preamp relay.

Then I got to thinking of both transverter slices being observed.  I did not want only the currently selected TX slice to have the preamp power available, I wanted both transverter bands to have the preamps on.  Only turn off the preamps when either transverter was in transmit.  That’s where the 2nd relay comes in for each band, that fires on PTT on frequency range, not on band only, and removes power from the preamps on both bands during TX on either band.  (Antennas on the same mast)

The preamp relays fire immediately on PTT, there is no delay set, as these we want to switch absolutely right away without RF present, not hot switched.


See this link for RF delay items for the Flex 6600 and SmartSDR



Note how the power to the preamps is connected to the NC contact, so RX condition is power to the preamps as long as it is enabled by the first relay.  So on PTT, the relay switches to NO and disconnects power to the preamp as long as the PTT switch is held.

The next two relays PTT the amplifier and then the transverter last.  The final 200 ms delay is for the RF from the Flex-6600 to be delayed after the transverter relay fires.  These delays can be reduced to a more comfortable level but were helpful at these time lengths to visually see how things were operating.

So that essentially uses the entire 8 channel board for both bands, but the flexibility using the USB bit menu is great.  One can set the delays… and turn off the preamps is you want to see their effectiveness.  One just mouse click the “PTT On” button on Bit Pin 1 (relay 2) for 222 MHz to take the power away from the preamp temporarily.  (Bit pin 5 for 432 – board relay 6)

Also, if I want to disable the power amplifier, I turn off the “PTT On” button on Bit Pin 2 (relay 3) for 222 MHz, where the RF will just run through the amp from the transverter.  (Bit Pin 6 for 432 – board relay 7)

As a request, it would be nice to have the label fields to have ability to be custom labels on the USB Bit cable menu.  “preamp”, “amp”, “Xvert”, etc.

Also, it seems that the 8 channel boards I have, both from SainSmart and Denkovi, list the hardware relays 1 through 8.  Would be nice to have 1 thru 8 on the USB bit menu in lieu of 0 thru 7.  Perhaps this field is modifiable?  Modifiable where the USB menu says “Pin” as it really is “Relay” in this case.  You could always have a default fall back in case you mess it up?

Just a heads up, I had one SainSmart board out of the box that did not work quite well.  So I ordered some Denkovi boards off of eBay from Bulgaria.  Below is the Denkovi version of the board.  I have yet to test it, but it sure looks nice.   Nice thing is the NO and NC contacts are labeled on the board.  I made the mistake on the SainSmart board where I wired both sides the same, then came to realize that the relays were revered from one side to the other, so the NC and NOs were switched. 

No wonder it didn’t work the first time! LOL


(Denkovi board above.... took about two weeks to get.  Packaged extremely well, very professional transaction from Bulgaria - looking forward to testing)

Good Luck in your setup.

73 – Mike- KM0T


  • Ed Stallman
    Ed Stallman Member ✭✭
    edited May 2019
    Mike , tnx so much for posting. With my 2m setup and no mast head preamp this will simplify things for me . Only PTT for amp and Transverter . The 4 relay board will do me just fine . One question , what were ur final PTT ms settings ? I'm thinking for my setup Relay 1 (AMP) = 0ms    Relay 2 (TVR) 20ms and (6600) TX = 40ms . Feedback is welcome 

    Ed N5DG
  • WA2SQQ
    WA2SQQ Member ✭✭
    edited May 2019
    Lots of great info thanks so much for sharing this
  • Ross - K9COX
    Ross - K9COX Member ✭✭
    edited May 2019
    Nice work and you are having fun
  • Clay N9IO
    Clay N9IO Member ✭✭✭
    edited August 2019
    Yes very nice work. That's true innovation. I have been using the Denkovi in a different way but have recently purchased an Antenna Genius so my thinking cap is on now. I will post a a later date as that project progresses. Picking up an Acom 2000 today so my shack will be in disarray for a little while as well.
  • KM0T
    KM0T Member ✭✭
    edited May 2019
    Well Ed I have not got to my final settings yet.  I would think your settings are fine, that short of time would seem almost instantaneous...  Im not that fast on the PTT and mic so I like a bit slower times... I think for me Im going to try my settings in half the time I have them set now and see how that feels, I just have not be able to be at the radio for some time now in order to test.  73 de KM0T

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