Re: Topband: RX antenna switching - unused ports

[Herbert Schoenbohm]

Brad, I have a 12x1 commercial Panasonic video switcher which is passive 
and terminates in 75 ohms all unused ports.  I used 1/2 wave feed lines 
which conceivable repeats the 75 ohm termination at the Beverage 
matching transformer.  I also use several 1:1 (DXE) isolation boxes 
about 30 feet from several Beverages to reduces feedline pickup coupling 
back into the Beverage matching transformer.



On 6/8/2017 8:06 AM, Maciej Wieczorek wrote:

Hi Brad,

what I can say from my perspective - in the last 10 years I have tried 
both grounding and terminating through 75ohm resistor. With the 
terminating I see absolutely no pattern distortion on my Beverage's, 
which was not so obvious when direct grounding was used.


My Bev's often are crossed 45 deg, height is 1,8-2,0m.  I use only 
isolated transformers / separate windings.


73's
Mac SP2XF / SN2M

- Original Message - From: "Brad Denison" 


To: 
Sent: Thursday, June 08, 2017 1:54 PM
Subject: Topband: RX antenna switching - unused ports



All,

 I am working a homebrew RX antenna switch box for my beverages, 
flags and

shared apex loop array and am looking for design advice.  Can someone
educate me on the proper way to handle unused ports:

1)  Leave all unused ports open
2)  Ground all unused ports
3)  Terminate unused ports to 75 ohm


I have seen various commercially available switch boxes with all of 
these

configurations but it is not clear to me if any of these variations are
best, i.e does it matter?

Thanks,

Brad, W1NT
_
Topband Reflector Archives - http://www.contesting.com/_topband



_
Topband Reflector Archives - http://www.contesting.com/_topband


_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: RX antenna switching - unused ports

[Maciej Wieczorek]

Hi Brad,

what I can say from my perspective - in the last 10 years I have tried both 
grounding and terminating through 75ohm resistor. With the terminating I see 
absolutely no pattern distortion on my Beverage's, which was not so obvious 
when direct grounding was used.


My Bev's often are crossed 45 deg, height is 1,8-2,0m.  I use only isolated 
transformers / separate windings.


73's
Mac SP2XF / SN2M

- Original Message - 
From: "Brad Denison" 

To: 
Sent: Thursday, June 08, 2017 1:54 PM
Subject: Topband: RX antenna switching - unused ports



All,

 I am working a homebrew RX antenna switch box for my beverages, flags and
shared apex loop array and am looking for design advice.  Can someone
educate me on the proper way to handle unused ports:

1)  Leave all unused ports open
2)  Ground all unused ports
3)  Terminate unused ports to 75 ohm


I have seen various commercially available switch boxes with all of these
configurations but it is not clear to me if any of these variations are
best, i.e does it matter?

Thanks,

Brad, W1NT
_
Topband Reflector Archives - http://www.contesting.com/_topband



_
Topband Reflector Archives - http://www.contesting.com/_topband