Using XG-3 to Evaluate RX Antenna Switch

[Pete Smith N4ZR]

I recently built an 8-way hub for receiving antennas, using an
inexpensive Chinese made remote control switch.

The switch works fine - at least the controller in the shack actuates
the remote relays, but I'm quite suspicious of the actual RF performance.

Here's what I'm wondering - can I use the XG-3 as a signal source?  I
was thinking I would connect its calibrated output to one of the antenna
inputs on the hub, then go back in the house and assess the resulting
levels on my receiver, both as a measure of throughput losses and of
isolation from the other inputs.  The input impedance of the hub's
antenna ports is somewhere in the 450-650 ohm range, because of a 9:1
binocular transformer between the switch's output and the feedline,
which is RG-6.

What do you guys think? Will I get any useful information from this?  
Will the transformer affect the RF voltage as seen on the other side of it.

Please be gentle - history major at work here.

--

73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.

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[Joe Subich, W4TV-4]

 > Will I get any useful information from this?

Yes.  You will be able to measure isolation (on/off and port to
port) but not absolute levels or insertion loss.

 > Will the transformer affect the RF voltage as seen on the other
 > side of it.

Yes.  Why don't you build up another transformer to step up the
XG3 output and match the impedance of the output (input) of the
switch.  Otherwise the voltage will be low (by about 19 dB =>
20 log(9)) due to the voltage step down in the transformer.

73,

    ... Joe, W4TV


On 11/16/2012 11:00 AM, Pete Smith N4ZR wrote:

> I recently built an 8-way hub for receiving antennas, using an
> inexpensive Chinese made remote control switch.
>
> The switch works fine - at least the controller in the shack actuates
> the remote relays, but I'm quite suspicious of the actual RF performance.
>
> Here's what I'm wondering - can I use the XG-3 as a signal source?  I
> was thinking I would connect its calibrated output to one of the antenna
> inputs on the hub, then go back in the house and assess the resulting
> levels on my receiver, both as a measure of throughput losses and of
> isolation from the other inputs.  The input impedance of the hub's
> antenna ports is somewhere in the 450-650 ohm range, because of a 9:1
> binocular transformer between the switch's output and the feedline,
> which is RG-6.
>
> What do you guys think? Will I get any useful information from this?
> Will the transformer affect the RF voltage as seen on the other side of it.
>
> Please be gentle - history major at work here.
>

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Please help support this email list: http://www.qsl.net/donate.html