Question on TX/RX antenna ports

Jim Kusznir <jkusznir@...>

Sorry, my diagram did not indicate that I do also have a band pass filter on the output of the isolator before the RF goes back to the radio.

In my current setup, I have 2 3-port TX/RX isolators going through a TX/RX "spur reducer" (rare item, couldn't find any details, not adjustable), and then into a standard Motorola square UHF cavity configured for band pass, before returning to the radio and going to the internal TX/RX switch.


On Mon, Feb 10, 2014 at 3:43 PM, John Lloyd <lloyd@...> wrote:
Hi Jim,

Remember that you should also install a low pass filter or band pass
cavity after the isolator to keep it off the antenna for IM reasons.

John Lloyd, K7JL

Jim Kusznir wrote:
> Ack, this message got mis-filed by my mail client, sorry for the delay!
> Here's my attempt at a block diagram...I'm pretty poor at diagramming...
> This is what my current Mitrek on the hill is configured as. Simple
> intercept of the TX line to the TX/RX switch. It breaks that out
> externally for isolator support, then brings it back into the box and
> uses the stock TX/RX relay for switching.
> For my purposes, it would be great if I could get a "standard" UDR,
> except there are two additional connectors on it (SMA is fine :) ),
> that breaks out the TX path (and if desired, the radio can ship with a
> jumper across these two ports such that it functions identically to a
> stock UDR). For those users who want to use seperate TX and RX
> antennas, I think they could just use the TX out and not send it back
> into the radio for their TX output, and use the "normal" antenna port
> for RX. That way the receiver is still protected against too much RF
> on transmit.
> Anyway, thanks for your response! My Mitrek on the hill isn't doing so
> well now, so I'm leaning more and more toward replacing it with a UDR
> as soon as I can get one (originally I was just going to get one for
> personal use).
> On Tue, Jan 28, 2014 at 1:31 PM, <bhhoyer@...
> bhhoyer@...>> wrote:
>     Jim,
>     I reviewed our setup and it requires an external switch to protect
>     the receive port and yes the Tx/Rx signal is available to drive it.
>     Please send me a block diagram of the application. I may be able
>     to make a slight change and use the internal switch.
>     Bryan


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