Langstone V2 as microwave 432 IF

[F1HDI]

Hi,

Is there around, for 432 IF, some designed modules, kits or PCBs taking the Tx1 and Rx1 of the pluto, when Txing deliver 33dBm or so with the right IN /OUT filtering , combining/switching the filtered TX and RX as a single IF for the microwave transverters (I am using DB6NT modules) ?.
Ideally also a +5-8v pushed on the IF path when TX.

I can cascade filters and chineses amps but a well designed 432 Tx and RX paths would be far better and more integrated. I guess I should stick with -10dBm Pluto output and +43dB gain (including gain to overcome filters loss) to stay within the pluto clean output range ?.
On the Rx side, not sure if I need filtering nor gain as the overall conversion gain is high.

BR
Jean-Marc

[g4eml]

I am not aware of any designs for a board as you describe, but it would be useful if someone was willing to do one.

The 70cms amplifier from G4BAO works well on the Pluto and Lime but it does not have the switching for the receive path. You would need to add a relay or solid state switch for that. With plenty of Rx gain in the tranverter you wouldn't need any filtering or amplification in the receive path.

Colin.

[g0mjw]

There is always the Lime-RFE but have a look at the Mini-kits Charon modules https://www.minikits.com.au/electronic- ... me242-23cm - if there is demand they may well do one for 70cm. I know they were planning 13cm.

It would not be all that hard to spin a PCB but I would think the mini-kits board would work just as will on 70cm with appropriate SAW filters replacing the 23cm ones.

Mike

Edit - you do not need 33dBm to drive a DB6NT transverter. Simply remove the input attenuator. DB6NT designed these to work with typical VHF/UHF radios like the FT290, IC202, FT817, that did not have a low power output.

[F1HDI]

Hi Mike,

You are fully right regarding DB6NT Tx input level, I should consider decreasing the 432 Tx FI down to the minimum .
In my 6 and 3cm setups, the 817 is delivering 800mW for around 8w on both bands , but if it works down to 80mW with still somme attenuation "in case of" , I should go that way. Again, I should mezsure or find the measurements , the pluto should be cleaner at -10dBm so I need to build a filtered 70cm amp with 30dB gain including filters loss with a 23dBm P1dB. Two cascaded MMIC and helical filters should do the job ?.
Unfortunately I am not very knowlegable with RF PCB designing, I should have a look at my fusion360 tool which I use for 3D modeling and printing (but not RF)

So G4BAO 2+W is overkill

Thank you for the hint
JM

[g0mjw]

Hi JM,

A couple of MMICs with a filter in between sounds like a good solution. Just be careful with the PCB layout to avoid it becoming an oscillator. You could probably use G0MRFs 2.4 GHz PCB design and replace the 2.4 GHz SAW filter with a 435MHz one. Alternatively there are Ebay/AliExpress modules.

For example a filter with SMAs https://www.ebay.co.uk/itm/314152428192 - apparently 2 dB loss but note maximum power 10 dBm, so keep it below 0 dBm, i.e put it at the input. Then perhaps something like https://www.ebay.co.uk/itm/275407306207 which will have probably 30 dB gain or so and at least comes in a nice box.

TX/RX switching will require a relay but at 70cm and 80mW it doesn't have to be good one. You could use on of these on a PCB https://uk.rs-online.com/web/p/hf-rf-relays/6168758 but honestly at 70cm in this application where you don't care much about the isolation because you can turn the PA off on receive nor the matching, you might just as well use a miniature G5V-1 signal relay.

Mike

[G4FRE]

I used one of the cheap chinese 3w out 0dbm in modules to drive my 432 MHz IF DB6NT transverter (24GHz) at the +20dbm level, I have mounted attenuators on the input and output and an MCL LPFso it can never reach full power. The 1st one broke but after i did the bias modification there have been no problems on the ones gitted inside my Portslang, Langstone or Portslang XV creations

The same setup also works fine on my 144MHz IF DB6NT transverteres (13/9/6/3cm/47G/76G)

Dave
G4FRE