Is it possible to listen to 4 2 meter frequencies AND 4 70cm frequencies simultaneously with a 6700?

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I think I read somewhere, that at most 4 receiver slices can be used with a transverter or a 2 meter LNA hooked up to the Xvtr connection.  I was wondering, if you placed something like Down East Microwave's 2 meter LNA on the Xvtr connection and monitored 4 separate frequencies, could you also use a DEMI 70cm transverter which uses a 28 MHz IF connected to, say Antenna B, and monitor another four 70cm frequencies simultaneously?

I realize that transmitting thru the transverter with it connected to Antenna B instead of Xvtr introduces the problem of attenuating the transmission power sufficiently, so as not to blow the transverter's transmit input, but purely as a means of receiving these 8 separate frequencies, is it possible or have I forgotten some important aspect of the 6700 that makes the idea unworkable? Perhaps switching the transverter's IF to one of the 6700's receive antenna inputs would ensure that the transverter will never be overloaded by full power transmissions by accident?

If this is possible, DEMI offers the option of transmission attenuation so that it can handle anything up to a 10 watt transmission.  Wouldn't this mean that you can select any of the 2 meter or 20cm frequencies and transmit without a worry of blowing out the 70cm transverter (as long as the power was below 10%)?

Any thoughts?

Thanks!

73,
Roy, AC2GS
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Roy Laufer

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Posted 4 years ago

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Luis del MOlino

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Roy:
About your question of receiving with 4 slices conencted with a 2 meter transverter and 4 slices with a 70 cm transverter at the same time with a 6700, I think you can do it using separated RX IF and TX IF outputs in each trasnverter
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One RX FI trasverter would be connected to RXA activated in one SCU and the other trasverter RX FI output to  RXB connected to the other SCU..

For transmission you have to select on 6500 the XTVR bands and you can put both transverters FI-TX connected in parallel to the XTVR output for transmmission and you can select the PTT of on of the transverters that will be activated selecting the transverter that will take the PTT action with TX1 or TX2 PTT output enabled (only one) for ransmiting.

I cannot garantee this solution will work for you because I own a 6500 with only one SCU and I cannot receive bothe bands at the same time. Instead I have to use a RF relay to change RX FI in 28 MHz from the VHF transverter to the RX FI for the UHF transverter in RXA, but I can select the PTT output with TX1 or TX2 PTT outputs pefectly..

Think about this and try it at your own risk.

Luis EA3OG
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Marc Lalonde

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Hi  each transverter use one SCU  so on a 6700 you have 2 SCU so you may monitor 2 transverter (2 Band)  whit 4 slice each   , but only TX on one at the time and ascoiated slice will muted on TX , so not full duplex here 

now if you what to put 2 transverter on same SCU it may have a trick (not yet tested)
use separate IF for TX and RX and mix it whit mini-circuit  signal combiner
Kunge  make transverter in 28 and 16mhz IF   so transverter not overlap each other
 transverter input filter will do the rest ...  but i will test it only later this spring
and will add bit of glue logic for disable the segond module on TX 

Marc L  VE2OLM
(Edited)
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Steve - N5AC, VP Engineering / CTO

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Official Response
On a FLEX-6700 you can place 4 receivers in the 2 meter band and 4 receivers in the 10m band. This would allow you to do what you are asking about.  Each band can be on a different antenna.
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Roy Laufer

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Excellent!  This will be great to "play" with when I am in a VHF/UHF frame of mind.

What kind of transverter input power range could I get away with when running the transverter thru Antenna B rather than Xvtr connection?  DEMI offers an option for as high as 10 watt input, but the model I have ordered is for the 100mW input power (due to the 6700's XVtr output of 10dBm).  I assume it wouldn't be difficult to lower the Antenna B output to a 10 watt range, but I doubt it can be brought down to a 100mW level.

Could I transmit thru a 100mW input transverter thru Antenna B safely?

Thanks!

Roy, AC2GS
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Steve - N5AC, VP Engineering / CTO

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Only the XVTR port will provide output.  If you want to transmit on both 144 and 28, you'll need to put a relay on the output of the port and control it based on the band.

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Luis del MOlino

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Roy

I have two Demi transverters, one for 144 and another for 432 and both accepts outputs from 1 mW to 10 W, adjusting the input configuration. The Elecraft transveters accepts these powers as well.

You can only use XTVR output of the Flex for both transverters, but I can assure you that my TX solution to supply the same output for both FI-TX inputs of both transverters in parallel works very well, because that allows selecting them by qcctivating one of the PTTs separately.

The problem with transverters is that the range of TX is limited to 6 MHz in the Elecraft and 4 MHz in the Demi. I have not succeded in expanding them more than that.

Luis EA3OG. 
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Roy Laufer

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Before I placed my order with Down East Microwave, I asked them if they could "open up" the 70cm bandwidth to use the entire bandwidth with my 6700.  DEMI's tech guy said that it would have a negative impact on the transverter's specification, but not by much, and that they would be glad to make that modification while they were building it!  I'm sure if you contact DEMI they would point you in the right direction to widen your transverter's band width as much  as you'd need.
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EA4GLI - 8P9EH - Salvador

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I am considering the combination to get Full Duplex TX in 2m and RX in 70cm for sat work but also have it so I can use the DEMI 2m amp and DEMI 70cm Transverter to work local repeaters.

If I configure a XVTR for UHF I have to TX through the XVTR port, I cannot select the ANT1 or ANT2 to TX.

As far as I can tell I will not be able to transmit on the DEMI transverter with ANT1 or ANT2.

Is this the case?

I can however, TX on 2m in either of the 3 ports (ANT1, ANT2 and XVTR) but it seems to me that the DEMI 2m amp is configured to use the XVTR por of the Flex 6700.

I am very confused!
(Edited)
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Sergey, R5AU

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i am agree Salvador, pity, this is must be improved for use 144 as is with XVTR port and other (ex UHF) with ANT2 for TX and RX2 for RX (for separate RX and TX), due this is limited today by  SSDR XVTR setup only:
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Roy Laufer

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I am not sure if the 6700's 10 dBm 2 meter output is connected to antennas 1 or 2. It may just be enabled in the XVTR connection (no doubt, Steve N52AC will correct me if I am wrong).

I have successfully utilized a relatively inexpensive microwave transfer switch to switch transmitting capability between the DEMI LDPA and 70cm transverter. I use a simple rocker switch, but with TTL logic latching versions of a transfer switch, this could be done under computer control.
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Sergey, R5AU

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Roy this is a issue, the target is activate FDX for SAT or other crossband, today this is fine working on SW but no capabilities in case usage XVTR subfolder in the radio setup, I think 6700 must Do It ! This is truely expectable from this radio.
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Steve - N5AC, VP Engineering / CTO

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The exciter output can only exit the radio at the XVTR port.
(Edited)
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Sergey, R5AU

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Hi Steve, this is clear for now, however what you advise for FDX VHF-UHF (or others)?
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Steve - N5AC, VP Engineering / CTO

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If you have the IF output (RX) from the UHF side of the transverter going to RX A or RX B of a 6700, you can TX on 2m while listening on UHF.  You should also be able to listen on 2m while TX on UHF I believe.
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EA4GLI - 8P9EH - Salvador

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Thanks for repaying Steve. I can see how to do the first one, but if I tx in uhf I will be using the xvtr port which is the same one where the 2m amp is connected and can't figure out how i get to rx on 2m. If I use rxb for 2m i need to physically move the connection on the demi amp to the rxb bnc connector losing tx capability. If I don't have the preamp of the demi the 2m losses a lot of rx capability.
Right?
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Steve - N5AC, VP Engineering / CTO

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I think the only good way to do this is to run split IF and connect the respective TX port to XVTR for transmit and leave the RX ports connected to RXA and RXB.  I've seen others suggest using ANT1 and ANT2, but I would not personally hook a transverter to a HF PA.  If a mistake can be made, I'm likely to make it.
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Roy Laufer

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Some people, like myself, already are using one of the RCVR inputs for a mag loop, and also are using DEMI's LDPA rather than a transverter for 2 meter work.

I still find my simple and inexpensive transfer switch solution to do everything I need (I grant you that with your suggestion there would be no need to swap inputs, but for me the benefits outweigh the extra step required)...

Your mileage might vary!
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EA4GLI - 8P9EH - Salvador

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Is that split if in the ldpa 2m amp as well as the 70cm transverter?
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K6OZY, Elmer

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I'd like better information about what to order from DEMI to do this setup too.   I currently own their 2M LDPA 75W version with common RF output for my 6700.   http://01895fa.netsolhost.com/PDF/LDPA_PD.PDF

 I would want to listen to 2M and 70CM at the same time.

I want to order their high power 70cm transverter:  http://fwfvq.tehfm.servertrust.com/product-p/l432-28hp.htm

I need to make sure I fully understand how we would hookup 70cm and which options I should order.  I will do a common RF output, but need guidance on the IF configuration and IF Drive level selections.

I will order it with Dual LO option so I could use it standalone on a future endeavor but will use the 10Mhz off the GPSDO to align it.

My current 6700 setup has a Carolina Windom on ANT1 and a Pixel Loop RF-Pro1B (Waldo) on RX B.   The 2M LDPA is connected to the XVTR obviously and PTT is on TX 2.   I use TX 1 to trigger my KPA500 amplifier for HF use.

Thanks for the guidance.
(Edited)
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Roy Laufer

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Great minds think alike <HI HI>.  I have a Pixel Pro-2B loop waiting for a break in the icy cold weather to pitch in the backyard.  I keep reading that if anything, it works better at 5-10 feet than 20+ foot elevation.  I'll have to test that out!  My primary antenna is an Alpha-Delta DX-CC (there's just no room in a small Brooklyn lot for such things as towers (my backyard is only 20 x 25 feet). My UHF/VHF is a Comet GP-6.

I have ordered both the DEMI 2M LDPA 75W 2M LNA (for sometime in March-April) and their L432-28HP (expected sometime in April-June) - I wish their delay from "order to ship" were better... 

I can tell you what options I chose.  I went with Common IF, 0-100mW (the specs for the 6700 give its top output at 10dBm = 100mW), HP Common RF, and I chose the Synth only (the 6700 is the only transceiver I have that can run a transverter, so I saved a few bucks there).

I ran it all by the DEMI tech guy and added in my order that this was intended for a 6700, and that I wanted it modified for the full Amateur Radio 70cm band.  I should be able to wander all over UHF and VHF simultaneously when DEMI is finished assembling my order.

The way I have it planned is a simple antenna switchbox that will take the 70cm tranverter's IF and switch it either to Receiver A  (for  the ability to have up to 4 slices of 2M on the Xvter input and 4 slices of 70cm on the Receiver A input) or to the 2M LDPA's transverter passthru (XVRT OUT) (for the abilty to power down the LDPA and transmit on 70cm with the XVTR passthru from the LDPA.

It's a plan.

Good luck to you!

Roy, AC2GS
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Stan - VA7NF

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DEMI listens to their customer.  Ask them to spec out what is needed to support multiple transverters; indicate there is the Flex community waiting for their professional opinions.

Of course, report back the answer or have them reply directly.


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John - WA7UAR

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Cross posting this helpful update.

I ordered my 2m and 70cm DEMI transverters based on these recommendations and the DEMI DIP switch:

https://community.flexradio.com/flexr...