[TowerTalk] Preamp Protection

Tue Jan 21 12:14:43 EST 2014

Good grief.  Sure it will work, but,
how about a three terminal regulator?
Or even a resistor and Zener?
WL

-----Original Message----- 
From: towertalk-request at contesting.com
Sent: Tuesday, January 21, 2014 12:00 PM
To: towertalk at contesting.com
Subject: TowerTalk Digest, Vol 133, Issue 46

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Today's Topics:

   1. Molded connectors (Carol Richards)
   2. 15M6DX boom to mast plate (Jorge Diez - CX6VM)
   3. Re: 15M6DX boom to mast plate (Hector Garcia,XE2K)
   4. Protection of a preamp (Lizeth Norman)
   5. Re: 15M6DX boom to mast plate (Jorge Diez - CX6VM)
   6. Re: Protection of a preamp (Patrick Greenlee)
   7. Re: Protection of a preamp (TexasRF at aol.com)

----------------------------------------------------------------------

Message: 1
Date: Mon, 20 Jan 2014 20:13:54 -0500
From: "Carol Richards" <n2mm at comcast.net>
To: <towertalk at contesting.com>
Subject: [TowerTalk] Molded connectors
Message-ID: <7E39CBF873B4471A93CE09119856C61E at HPDesktop>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original

I have been using 8-pin molex type trailer cables. Both the male and female
come with  #12 or #14 gauge stranded pigtails, about 3 feet long. They work
great/

I got them from wiringproducts.com

Carol

------------------------------

Message: 2
Date: Tue, 21 Jan 2014 10:18:30 -0200
From: "Jorge Diez - CX6VM" <cx6vm.jorge at gmail.com>
To: <TOWERTALK at contesting.com>
Cc: 'Kurt Andress' <k7nv at contesting.com>, 'Stan Stockton'
<wa5rtg at gmail.com>
Subject: [TowerTalk] 15M6DX boom to mast plate
Message-ID: <52de659d.269aec0a.3192.ffffe275 at mx.google.com>
Content-Type: text/plain; charset="us-ascii"

Hello

I am reinstalling a 15M6DX. Boom is 2.5 inches

The mast to boom plate seems very small for a 44 ft boom antenna, is just 8
x 8 inches

Anyone replaced this factory plate with another option?  Where to find it?

Thanks,

Jorge

CX6VM/CW5W

------------------------------

Message: 3
Date: Tue, 21 Jan 2014 08:02:41 -0800 (PST)
From: "Hector Garcia,XE2K" <j_hector_garcia at sbcglobal.net>
To: Jorge Diez - CX6VM <cx6vm.jorge at gmail.com>,
"TOWERTALK at contesting.com" <TOWERTALK at contesting.com>
Cc: 'Kurt Andress' <k7nv at contesting.com>, 'Stan Stockton'
<wa5rtg at gmail.com>
Subject: Re: [TowerTalk] 15M6DX boom to mast plate
Message-ID:
<1390320161.25825.YahooMailNeo at web181602.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

Jorge
You will like to see this

http://www.dxengineering.com/techarticles/antennaconstruction/modifications-to-the-m2-model-40m4lldd

?
J.Hector Garcia ?XE2K / AD6D
Mexicali B.C  DM22fp / El Centro
P.O.Box 73
El Centro CA 92244-0073
http://xe2k.net
Tweeter @XE2K

________________________________
From: Jorge Diez - CX6VM <cx6vm.jorge at gmail.com>
To: TOWERTALK at contesting.com
Cc: 'Kurt Andress' <k7nv at contesting.com>; 'Stan Stockton' <wa5rtg at gmail.com>
Sent: Tuesday, January 21, 2014 4:18 AM
Subject: [TowerTalk] 15M6DX boom to mast plate

Hello

I am reinstalling a 15M6DX. Boom is 2.5 inches

The mast to boom plate seems very small for a 44 ft boom antenna, is just 8
x 8 inches

Anyone replaced this factory plate with another option?? Where to find it?

Thanks,

Jorge

CX6VM/CW5W

_______________________________________________

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TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

------------------------------

Message: 4
Date: Tue, 21 Jan 2014 11:14:16 -0500
From: Lizeth Norman <normanlizeth at gmail.com>
To: towertalk <towertalk at contesting.com>
Subject: [TowerTalk] Protection of a preamp
Message-ID:
<CAJUhCTO-LdUJHScaDb4FCWSGz_eq7RyX2zyK8iOtTiSH4Hj+WQ at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Hi all!
I have a preamp that I switch in and out with a pair of spdt coaxial
relays. The NC positions pass through and the NO positions hold the preamp.
The relays are +24Vdc and the preamp needs ideally 12Vdc.
Presently, I have the preamps hooked up to +24Vdc and they are frying.
What I'd like to do is when I key the relay, also feed the preamp through
20 diodes to drop the Voltage to something respectable. Possibly using a
100uF cap across the preamp.
Am I asking for trouble? Do dragons live here?
Norm n3ykf

------------------------------

Message: 5
Date: Tue, 21 Jan 2014 14:23:38 -0200
From: "Jorge Diez - CX6VM" <cx6vm.jorge at gmail.com>
To: <TOWERTALK at contesting.com>
Subject: Re: [TowerTalk] 15M6DX boom to mast plate
Message-ID: <52de9f11.269aec0a.3192.7a10 at mx.google.com>
Content-Type: text/plain; charset="us-ascii"

Wow!

They use the same plate in this monster 4 elements 40 mts yagi!, incredible.

Thanks for the link, just what I am looking for

73,

Jorge

De: Hector Garcia,XE2K [mailto:j_hector_garcia at sbcglobal.net]
Enviado el: martes, 21 de enero de 2014 02:03 p.m.
Para: Jorge Diez - CX6VM; TOWERTALK at contesting.com
CC: 'Kurt Andress'; 'Stan Stockton'
Asunto: Re: [TowerTalk] 15M6DX boom to mast plate

Jorge

You will like to see this

http://www.dxengineering.com/techarticles/antennaconstruction/modifications-
to-the-m2-model-40m4lldd

J.Hector Garcia  XE2K / AD6D
Mexicali B.C DM22fp / El Centro
P.O.Box 73
El Centro CA 92244-0073
http://xe2k.net
Tweeter @XE2K

  _____

From: Jorge Diez - CX6VM <cx6vm.jorge at gmail.com>
To: TOWERTALK at contesting.com
Cc: 'Kurt Andress' <k7nv at contesting.com>; 'Stan Stockton' <wa5rtg at gmail.com>

Sent: Tuesday, January 21, 2014 4:18 AM
Subject: [TowerTalk] 15M6DX boom to mast plate

Hello

I am reinstalling a 15M6DX. Boom is 2.5 inches

The mast to boom plate seems very small for a 44 ft boom antenna, is just 8
x 8 inches

Anyone replaced this factory plate with another option?  Where to find it?

Thanks,

Jorge

CX6VM/CW5W

_______________________________________________

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TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

------------------------------

Message: 6
Date: Tue, 21 Jan 2014 10:25:08 -0600
From: "Patrick Greenlee" <patrick_g at windstream.net>
To: "Lizeth Norman" <normanlizeth at gmail.com>, "towertalk"
<towertalk at contesting.com>
Subject: Re: [TowerTalk] Protection of a preamp
Message-ID: <83064646D5CF487AA6DB6FE56CE66B6D at PatrickLaptop>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original

Well that is one way.  Another is to use a (one, 1 , ein un) Zener diode to
subtract out the difference.  Another way is to measure the current draw of
the amps when operated on proper voltage and then calculate the value of a
series resistor required to drop the excess voltage at that current.

For your convenience:  I=E/R   P=IE (don't forget to calc the power
dissipated by the R so you can size it (them if you use more than one.)

A cap across the power connections at the amps won't hurt but probably not
THAT BIG.

Patrick NJ5G

-----Original Message----- 
From: Lizeth Norman
Sent: Tuesday, January 21, 2014 10:14 AM
To: towertalk
Subject: [TowerTalk] Protection of a preamp

Hi all!
I have a preamp that I switch in and out with a pair of spdt coaxial
relays. The NC positions pass through and the NO positions hold the preamp.
The relays are +24Vdc and the preamp needs ideally 12Vdc.
Presently, I have the preamps hooked up to +24Vdc and they are frying.
What I'd like to do is when I key the relay, also feed the preamp through
20 diodes to drop the Voltage to something respectable. Possibly using a
100uF cap across the preamp.
Am I asking for trouble? Do dragons live here?
Norm n3ykf
_______________________________________________

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TowerTalk mailing list
TowerTalk at contesting.com
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------------------------------

Message: 7
Date: Tue, 21 Jan 2014 11:31:03 -0500 (EST)
From: TexasRF at aol.com
To: normanlizeth at gmail.com, towertalk at contesting.com
Subject: Re: [TowerTalk] Protection of a preamp
Message-ID: <7a632.26a63011.400ffac6 at aol.com>
Content-Type: text/plain; charset="US-ASCII"

Norm, yes, there are dragons here!

Relay isolation has to be sufficient keep the rf voltage from destroying
the preamp. Often times a single relay doesn't give enough isolation and
tandem  relays are required. This applies to both the input and output of 
the
preamp.

Another issue is the relays will generate an inductive voltage kick at turn
off. You can add filtering and clamping diodes but the spike can happen so
quickly that the preamp still gets a hit before the protection circuit
does it's  job.

Timing is critical. The relays need enough time for the contacts to settle
before rf is present.

VHF/UHF operators typically use a sequencer to turn things on/off in the
right order and time to protect the preamp. The requirements for complete
protection are not trivial!

73,
Gerald K5GW

In a message dated 1/21/2014 8:14:48 A.M. Pacific Standard Time,
normanlizeth at gmail.com writes:

Hi  all!
I have a preamp that I switch in and out with a pair of spdt  coaxial
relays. The NC positions pass through and the NO positions hold the  preamp.
The relays are +24Vdc and the preamp needs ideally  12Vdc.
Presently, I have the preamps hooked up to +24Vdc and they are  frying.
What I'd like to do is when I key the relay, also feed the preamp  through
20 diodes to drop the Voltage to something respectable. Possibly  using a
100uF cap across the preamp.
Am I asking for trouble? Do dragons  live here?
Norm  n3ykf
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End of TowerTalk Digest, Vol 133, Issue 46
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