Daytime Impedance high?

AM Radio discussion. Directional arrays are FUN!
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RGORJANCE
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Re: Daytime Impedance high?

Post by RGORJANCE » Thu Jun 22, 2017 7:36 am

Deep:

Thanks for the update re coil parts from Gates Air.

Good thing I got some spares on hand for those coils, and two spare coils. Now you got me wondering about the motorized contactor parts. Only got a couple fingers left for them. :(

Fossil

lbwireless
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Re: Daytime Impedance high?

Post by lbwireless » Thu Jun 22, 2017 9:05 am

LBA Technology has been supplying RF components and systems for many years Their products are at https://www.lbagroup.com/products/technology. Your contact on the coil would be Jerry.Brown@lbagroup.com.

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Deep Thought
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Re: Daytime Impedance high?

Post by Deep Thought » Thu Jun 22, 2017 10:05 am

RGORJANCE wrote:
Thu Jun 22, 2017 7:36 am
Deep:

Thanks for the update re coil parts from Gates Air.

Good thing I got some spares on hand for those coils, and two spare coils. Now you got me wondering about the motorized contactor parts. Only got a couple fingers left for them. :(

Fossil
I had the same experience. The "incident" in Palm Springs a couple years back was remedied with a new exact-same coil from GatesAir (both the engineer and I were amazed they had one) but the second flameout in Minnesota earlier this year resulted in a "no we don't have any more of those" and the referral to KTL.

As for the spam above this post, just don't. :roll:
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

Steve Brown
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Re: Daytime Impedance high?

Post by Steve Brown » Fri Jun 23, 2017 10:07 am

Fossil and anyone else who might be interested. Contract engineer Doug Thompson knows where there are at least four of the Harris sliding motorized contactors that were replaced with Kintronics contactors some years ago. The Harris contactors didn't seem to want to slide well in cold weather here in MN. Contact Doug at (651) 247-8119 if you're interested.

Radio Ranger, Mpls

awsherrill
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Re: Daytime Impedance high?

Post by awsherrill » Fri Jun 23, 2017 10:42 am

When Harris had their big inventory sell-off a few years ago (prior to the broadcast division getting spun off and becoming Gates-Air), did they have any AM parts and pieces that wound up being purchased by someone? I recall that SCMS wound up with a fair amount of Harris stuff.

lbwireless
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Re: Daytime Impedance high?

Post by lbwireless » Fri Jun 23, 2017 12:23 pm

@Deepthought - Spam, indeed. My post was meant to be helpful and you have no basis for impugning it.

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NECRAT
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Re: Daytime Impedance high?

Post by NECRAT » Fri Jun 23, 2017 3:57 pm

lbwireless wrote:
Fri Jun 23, 2017 12:23 pm
@Deepthought - Spam, indeed. My post was meant to be helpful and you have no basis for impugning it.
Check your PMs.
http://www.necrat.us

"Arguing with an engineer is like mud wrestling with a pig. After a couple of hours, you realize the pig likes it"

grich
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Re: Daytime Impedance high?

Post by grich » Wed Jun 28, 2017 3:01 pm

Hopefully the original problem doesn't become moot as a tornadic thunderstorm threatens the KMA tower site here in the next few minutes...

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Shane
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Re: Daytime Impedance high?

Post by Shane » Wed Jun 28, 2017 3:32 pm

Sounds like they made it through. Praise God, the funnel lifted as it crossed Shen just a few blocks south of downtown. The same storm is well east now and the funnel has been up and down and up again.

Pretty intense hail not too far from the KMA site but never lost carrier. The NWS EAS relay was interrupted a few times.

Great coverage, KMA folks!
Mike Shane, CBRE
---Omaha---

mbrockm
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Re: Daytime Impedance high?

Post by mbrockm » Wed Jun 28, 2017 9:23 pm

We will see what daylight shows tomorrow at KMA sites
Mark Brockmeyer
KMA Engineering

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Re: Daytime Impedance high?

Post by mbrockm » Mon Jul 10, 2017 5:29 pm

I got my replacement coil from Kintronics today. The old coil was a 6" outside diameter coil with 23 turns. The replacement from Kintronics is only a 5" outside diameter coil with 22 turns. The windings on both are 1" wide flat copper. Circuit wise the coil is across the common point and ground. The wiper arm adjusts the power to the south tower in the DA. Is this going to work? The difference in coil size has me wondering if this will work. Attached our phasor diagram. Coil is L6 in the south tower circuit.
Attachments
Phasor.pdf
(213.82 KiB) Downloaded 27 times
Mark Brockmeyer
KMA Engineering

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Deep Thought
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Re: Daytime Impedance high?

Post by Deep Thought » Mon Jul 10, 2017 10:23 pm

That is a very non-critical part of the circuit, forming a power divider based on roller position on the coil and the ratio between the "top" and "bottom" parts. You may notice a small difference in phase (<5°) due to the slightly different coil value and it'll probably shift the common point tuning a bit, but neither of those are issues with most phasors.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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