Full Duplex Satellite Station - Multiple Transverters with DIPS how to?

  • 2
  • Question
  • Updated 3 weeks ago
I am putting together a full duplex satellite system for my Flex 6700 using the DEMI 2MLPDA, DIPS, and DEMI/Q-Signal Transverters for 70 cm and higher. I want to be able to support a total of 4 transverters along with the 6700's 2M output. I'd like to support the following operating configurations:
  1. Weak signal simplex Tx/Rx on 2M, 70cm, 23 cm, 5 cm (5 GHz), or 3 cm (10 GHz)
  2. Full duplex satellite V/U or U/V
  3. Full duplex satellite L/V
  4. Full duplex satellite 5G/10G
  5. Full duplex satellite 5G/U or 5G/V
I am planning to use this setup to operate my station remotely and the 2MLPDA and all four transverters will need to be turned on at the same time.

I have come up with a design that I think might work and I'd like to get some feedback from the Flex support folks and others here in the forums. Here's the design -



I have the following questions:
  1. Will all of the above listed modes (especially the duplex listen while in Tx on another band) work correctly?
  2. Is it OK to use simple BNC T connectors to fan out the 28MHz XVERT Tx IF to four transverters? Are they any issues with signal levels or loading on the Flex 6700 output if I do this?
  3. Since all for transverters are on at the same time, I am assuming I must switch the RX IF so that only one transverter is connected to RX A on the 6700 at a time. I am planing to use BNC relays with good isolation characteristics and control them with a BITS cable. Are there any issues with this approach?
  4. Does my configuration support simultaneous uplink Tx on one transverter while simultaneously listening on a different transverter's downlink? For example, can I Tx on a 5 GHz uplink and list on a 10 GHz downlink at the same time with this setup?
  5. I would expect to locate the 5 GHz and 10 GHz transverters remotely at the antennas. Are there any issues with transporting the 28 MHz TX IF and RX IF through longer runs of coax cable? Is there a good way to isolate/buffer these connections to protect the rest of the gear that is indoors?
  6. Are there any other issues or concerns that I should be aware of with this design?
Thanks in advance for the help!

Fred, AB1OC
Photo of Fred, AB1OC

Fred, AB1OC

  • 18 Posts
  • 1 Reply Like

Posted 3 weeks ago

  • 2
Photo of K6HN

K6HN

  • 12 Posts
  • 2 Reply Likes
Interesting design that appears simple, yet effective. How will you control the PTT to each Transverter?

Photo of Fred, AB1OC

Fred, AB1OC

  • 18 Posts
  • 1 Reply Like
Via a pair of BITS cables.
Photo of K6HN

K6HN

  • 12 Posts
  • 2 Reply Likes
The 'T' connector method would most likely work, but the best way to split the Flex Xvrtr output and provide proper loads along with even power across the ports would be to use a passive 4-way splitter. Mini-Circuits has many models and you can find them used easily.

Photo of Fred, AB1OC

Fred, AB1OC

  • 18 Posts
  • 1 Reply Like
Thanks for the suggestion on the splitter. I will go that way. Does anyone know if the Flex 6700 28 MHz XVERT out path is a 50 or a 75-ohm design?
Photo of Mack McCormick

Mack McCormick, Elmer

  • 323 Posts
  • 116 Reply Likes
Fred,

I use a similar setup with a LDPA, 3 DEMI transverters, and the DIPS. The main thing I do differently is I use a Mini-Circuits 4 way splitter (50 ohm). I also use a 12V 8 relay board for switching the transverter outputs and PTT. This board appears as a a bit cable in the Flex USB setup form: https://www.amazon.com/gp/product/B0093Y89DE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 .

Please note with a 4 way splitter you'll have 7 dBm loss on each output plus the loss over coax up to your tower so you must compensate appropriately. 

Good luck with your project!

73,

Mack
W4AX
Alpha Team
Photo of Fred, AB1OC

Fred, AB1OC

  • 18 Posts
  • 1 Reply Like
TU Mack! Want to be sure I understand what you are doing. You are using the relay board to switch PTT and to switch the Rx outputs from your transverters, one at a time, to be connected to the RX input on the Flex correct? I have ordered a Mini-Circuits 4-way splitter for the input side of the transverters as well.
Photo of Mack McCormick

Mack McCormick, Elmer

  • 323 Posts
  • 116 Reply Likes
Fred,

Yes, your understanding is correct.

Mack
W4AX
Photo of KF4HR

KF4HR

  • 528 Posts
  • 149 Reply Likes
Fred - I'm in the process of also setting up my 6700 for multiple Transverters.  My concern with your diagram concerns the possible input impedance differences of the BNC splitters, or power losses with the 4-way splitter arrangement. 

I'm wondering if there might be a way to incorporate a multi-port RF relay to switch the 28mhz IF and between Transverters, or perhaps a switching device that could switch both the 28Mhz IF and the Relay 1, 2, 3 connections?  
(Edited)
Photo of Fred, AB1OC

Fred, AB1OC

  • 18 Posts
  • 1 Reply Like
Hi Mack,

I think that the splitter will be OK. A typical 4-way power divider (mini-circuits) will have a little more than 6 dB of loss as long as any unused ports are terminated with 50 ohms. The power divider should also take care of any potential impedance mismatches. Most transverters have more than enough gain adjustability to handle this amount of extra lost. Check out the specs on the DEMI/Q-Signal 70 cm transverter vs. the output level specs on the FLex 6700 for example.

Fred, AB1OC