[NLRS] 432 sprint and antenna stacking question

[Lloyd - N9LB]

Hello Mary,

The issues you bring up are exactly why I am still struggling to get my multi-band station going.  I can't afford any more burn-outs.

Also, I believe the "recommended distances" for stacking antennas are for minimum pattern distortion.  
Undesired coupling between antennas can still produce several watts of power on the feed of nearby antennas.  ( I measured it here - was quite surprised )

I'd like to hear more from folks that have addressed this problem.

73

Lloyd

-----Original Message-----
From: Mary Brown [mailto:maryalanab at gmail.com] 
Sent: Friday, April 16, 2021 5:04 PM
To: 'Ronald Bergantzel' <ka0ryt1 at yahoo.com>; 'Lloyd - N9LB' <lloydberg at tds.net>
Subject: RE: [NLRS] 432 sprint and antenna stacking question

Hard to do running a Beko preamp on 432... unless I can break the power to the relay box in the aux connector... have to dig out a manual.

Going to have Beko amps on 2m, 432, and 23cm(1kw, 750 watts, 550 watts). 

Also brings up the question of relay timing... TX delay on the IC-9700 is only 30ms, I need to ask Beko what their sequencer timing is or switch each amp and let it key the 9700... my cable rats nest is going to get worse! LOL! 

Mary
W0AAT

-----Original Message-----
From: nlrs-bounces at mailman.qth.net [mailto:nlrs-bounces at mailman.qth.net] On Behalf Of Ronald Bergantzel via NLRS
Sent: Friday, April 16, 2021 4:59 PM
To: 'NLRS'; Lloyd - N9LB
Subject: Re: [NLRS] 432 sprint and antenna stacking question

 Hello Mary and Lloyd - Yes , if I were going to do an antenna arrangement like Mary's , I would make a foolproof way to ALWAYS have the rx preamps be switched into a dummy load thru my isolation relay when xmitting - especially harmonic related bands = i.e 432 at 1296 and 222 at 432 , etc .   ( I always run 2 t/r relays on my systems due to QRO power levels ) . My tried and trued system uses 1/4 wave low loss cable between the 2 relays ( high power relay and isolation relay )  at my freq of operation . This has worked for years and years and years of legal limit continous operations running digital duty cycles .... Your mileage may vary - C U on Wednesday evening . 73s , Ron KA0RYT EN35ct - still tinkering at the farm BTW - there's a good chance that I will be QRV before the contest Wednesday late afternoon  performing an improved airflow mod on the cavity and will be doing some FT8 testing on 432.174 before the contest starting time .....
    On Friday, April 16, 2021, 04:40:45 PM CDT, Lloyd - N9LB <lloydberg at tds.net> wrote:  
 
 Hello Mary,

After running high power ( 100w + ) I have burned out multiple pre-amps and front ends from cross-talk between different VHF and UHF antennas that share the same mast pipe.
I did space each Yagi at least 1/2 boom length or 1 to 2 wavelengths.

For the 432 sprint, I suggest that you just disconnect the other bands.

I am still working on switching systems for the multi-band contests to simultaneously protect all the pre-amps and front ends from burn-out.

73

Lloyd - N9LB

-----Original Message-----
From: nlrs-bounces at mailman.qth.net [mailto:nlrs-bounces at mailman.qth.net] On Behalf Of Mary Brown
Sent: Friday, April 16, 2021 4:30 PM
To: 'NLRS' <nlrs at mailman.qth.net>
Subject: [NLRS] 432 sprint and antenna stacking question

I will be on for the sprint from en24gp.

And question on stacking. I need to put 222, 432, and 23cm on one tower.

Antenna and half stacking distance

222-10ez 3' 3" half stacking distance

432-9wl 3' half stacking distance

23cm35x4 on an H frame 1' 2 1/2" half stacking distance

Thoughts were 222 on the bottom 2' above the tower

Then 23cm35's 4'5" above that

Then the 432 antenna 4'2" above those

According to DX Engineering mast load this will survive 120mph. 

Thoughts? Going to be running power on 432 with 750 watts and 23cm with 550 watts,  so interactions? Preamp issues from the RF fields? Preamps will be below tower top so it will just be whatever the antenna picks up from the other bands.

Would love to space this more but this is going on a bracketed Rohn 25 on the side of the house. right at max wind load. 

Mary
W0AAT

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