Portsdown – 8 way RF output switch

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
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m1cdq
Posts: 113
Joined: Thu Feb 28, 2019 4:28 pm

Portsdown – 8 way RF output switch

Post by m1cdq » Wed Nov 13, 2019 5:39 pm

on the portsdown the – 8 way RF output switch can you run 2 in parallel.
my reason of thinking is as i've been reading it can now sort of control a minitioune board.
Im just about to start building a portsdown using a limemini.
use 1 Portsdown – 8 way RF output switch for the lime output to different PA's and ant's
use 2 Portsdown – 8 way RF output switch as a switched input 8 different feeds in to the minitioune
paired up to if i'm using separate ant's for tx and rx
so if im on 70cms i can feed a 70cm ant to the minitioune or if im on 23 cms it will switch to the 23cm ant feed on the minitioune
so they change in sync one for input one for output

g8gtz
Posts: 1737
Joined: Wed Apr 07, 2010 6:26 pm

Re: Portsdown – 8 way RF output switch

Post by g8gtz » Wed Nov 13, 2019 6:25 pm

Yes - I'm thinking the same way and Dave G8GKQ has already done it, you just don't need the MMIC amp on board which will need to be shorted out.

Re control - it is a case of simple DC levels on 3 pins to select the right port. These can be driven by Portsdown for auto selection but I'm going to put in manual control as well.

73
Noel - G8GTZ

m1cdq
Posts: 113
Joined: Thu Feb 28, 2019 4:28 pm

Re: Portsdown – 8 way RF output switch

Post by m1cdq » Wed Nov 13, 2019 6:36 pm

cheers for that noel
just thinking. maybe a new board design for this purpose. But with 8 bias-t voltage inputs for mast head pre-amps at 12v or lna at 5v ect
or just mod the oric board as suggested by pass the mmic and add some bias boards to the outputs

G4FRE
Posts: 197
Joined: Fri May 26, 2017 6:57 am

Re: Portsdown – 8 way RF output switch

Post by G4FRE » Wed Nov 13, 2019 7:12 pm

Thats the way I do it. I buffer the 3 pins and feed them to a 2nd 8 way board mounted in an external box. I bypassed the mmic as I already have enough gain in my mhp/xverters to overcome the few db loss of the switch ic

Dave

G4FRE
g8gtz wrote:
Wed Nov 13, 2019 6:25 pm
Yes - I'm thinking the same way and Dave G8GKQ has already done it, you just don't need the MMIC amp on board which will need to be shorted out.

Re control - it is a case of simple DC levels on 3 pins to select the right port. These can be driven by Portsdown for auto selection but I'm going to put in manual control as well.

73
Noel - G8GTZ

m1cdq
Posts: 113
Joined: Thu Feb 28, 2019 4:28 pm

Re: Portsdown – 8 way RF output switch

Post by m1cdq » Wed Nov 13, 2019 7:49 pm

If i have this right remove the parts in red and just bridge
to give you a 8 in to 1 selectable rf INPUTS for a receiver

Image
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