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   Home   Help Search  
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Author Topic: HT w/ Base Antenna  (Read 848 times)
W8WMM
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« on: November 14, 2017, 08:22:38 AM »

How do I prevent damaging my HT when using it with a base antenna? The antenna is properly grounded with a lightning arrester to station ground, but the HT is not. I would prefer not to have to modify the HT to ground it.
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SWMAN
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« Reply #1 on: November 14, 2017, 09:10:21 AM »

 I just unhook antenna on my HT when not in use.
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K5LXP
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« Reply #2 on: November 14, 2017, 09:20:26 AM »

"Prevent"-?  Might be a bit unrealistic/impractical to effect that level of protection for a device never intended to be used as fixed equipment.  Is it plugged in to mains?  That would be another path of ingress.  A DC grounded antenna, along with a DC shunt arrestor like the ICE brand would be a good start.  Adding an isolating filter would add more protection.  You can easily spend way more on protection than the radio is worth so if reliability and durability is paramount, an HT may not be the best choice.

Mark K5LXP
Albuquerque, NM
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W8WMM
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« Reply #3 on: November 14, 2017, 11:45:35 AM »

I understand that base ops are not the HT's intended use. It is what I have for a 2m radio, and will likely be for a while. (retired, fixed income, etc.) It is not connected to house AC. The charger base is, but the radio isn't on the charger while in use.
Thanks for your comments.
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AC2EU
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« Reply #4 on: November 14, 2017, 03:21:46 PM »

I understand that base ops are not the HT's intended use. It is what I have for a 2m radio, and will likely be for a while. (retired, fixed income, etc.) It is not connected to house AC. The charger base is, but the radio isn't on the charger while in use.
Thanks for your comments.

I am not big on VHF, so I  find a HT handy for monitoring emcomm or NOAA weather reports.
I have and outside quarter wave vertical with radials to improve reception/TX
My FT60 has an SMA connector which is easy to unscrew  from the the radio.
Of coarse the the antenna is grounded before entering the house as per the NEC.
That and a spark gap arrestor is about all you can do beyond detaching the radio when it's not in use.
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KD4LLA
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« Reply #5 on: November 14, 2017, 06:39:23 PM »

I would be more worried about lightning coming in through my phone line than a direct hit to an antenna on the house.

I have always had 2-6 outdoor antennas (plus over-the-air TV antenna on the roof line) in the air around my home.  And the only lightning damage I have had is two computer wi-fi routers.
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WB6BYU
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« Reply #6 on: November 14, 2017, 06:43:23 PM »

Quote from: KE8ICK

How do I prevent damaging my HT when using it with a base antenna?...



What sort of damage are you hoping to prevent?  I used my HT on external
antennas for years, and 30 years later it still works fine.

If you are worried about lightning, then grounding the radio won't help,
since it is already grounded via the coax shield.  Besides, if you are
holding the radio when you get a strike, the radio isn't going to be the
most important thing to worry about.

The coax should run from your antenna to the ground rod / lightning
arrestor, then to the shack.  The lightning ground rod needs to be bonded
back to your electrical service ground for safety.  

One other thing you can try is adding a big resistor, RF choke, or shorted
coax stub across the coax if there isn't a good D.C. ground already on
the coax center conductor.  ( Many antennas may provide a path to ground.)
That will help prevent static build-up on the antenna, which is a separate
condition from lightning.

In a direct strike, lightning will do whatever it wants to do.  You can
encourage it to take particular paths rather than others, but at 10,000+
Amps in a down strike, and enough voltage to jump several miles through
the air, it doesn't always find our efforts very convincing.

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WA3SKN
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« Reply #7 on: November 15, 2017, 07:15:33 AM »

As long as the antenna is grounded for static dissipation you should be good to go.
73s.

-Mike.
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K8AXW
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« Reply #8 on: November 15, 2017, 09:29:56 AM »

To my simple mind, this is an  example of "overthinking" a non-problem.

There isn't anything wrong with using an HT on a base antenna.  When not in use, simply disconnect it for the antenna.  As for the charging base, leave it plugged in if you wish.

When I don't use my station ALL antennas are disconnected.  The gear is still connected to the mains though. 

When I first started hamming, I would disconnect all gear from the mains and then later when I built a ham shack desk for the gear, the first thing in the AC line was a LARGE double-pole knife switch  in a steel box which was a very common house wiring fixture many years ago.

After many years of using the knife switch to disconnect everything I became complacent and stopped using it. I may regret this one day but have gotten away with this practice for several decades.

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K0UA
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« Reply #9 on: November 15, 2017, 01:00:42 PM »

Pretty much what I was thinking .  This is a non problem.  Unplug the HT
when lightning come around or when done operating.
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W8WMM
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« Reply #10 on: November 16, 2017, 04:40:29 AM »

I appreciate all the inputs.
If I momentarily short the active and ground side of the coax before connecting to the HT it will discharge any static charge and not fry the HT. I do know better than to leave things connected during electrical storms.
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K0UA
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« Reply #11 on: November 16, 2017, 06:39:30 AM »

On other item:  A lot of HT's are not very good receivers.  They don't have much in the way of "front end" components and when connected to a good antenna bringing in strong signals, they are prone to front end overload.  It all depends on how good this antenna is you are connecting to, and how good the front end of the HT is.   All are not created equal. But it is something to be aware of.  An HT might be fine on its own "rubber duck", but hook it to a 15 element beam at 100 feet, and it might just lay down and die.  Or it may work fine.
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WB6BYU
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« Reply #12 on: November 16, 2017, 07:22:53 AM »

Check the DC resistance across the coax connector:  if it reads any sort of resistance below
5 Megohms or so, that is sufficient to prevent any static build-up.

You can also check the resistance across the antenna connector on your HT in receive mode:
if that is low, then static charges can't build up as long as the antenna is connected to the radio.

(That assumes that the coax shield is grounded at some point.)

If the coax measures an open circuit, you can add a DC connection across it to dissipate any
static build-up in a couple of ways:  probably the simplest is to insert a T connector in one of
the junctions in coax somewhere and add either a quarter wave shorted stub of coax for 2m
or a 100K ohm resistor (or any other big number) across it.  Either will prevent static build-up.
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W8WMM
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Posts: 30




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« Reply #13 on: November 16, 2017, 11:47:36 AM »

Well, it (Icom V80) didn't puke when I replaced the rubber duck with a quarter wave whip. The reception was definitely better. The base antenna is an Arrow 2m GP up about 30'. I don't expect much stronger signals from it than from the whip.
The coax shield is well grounded. The feedline goes through a lightning protector, also grounded.
Maybe I have "overthought" this. I read a horror story about an HT being fried when connected to a base antenna on which a static charge had built up. I would rather be safe than sorry.
Before too awfully long, I plan to get probably a mobile 2m xcvr for the base station. The HT has to pull double duty until then.
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AA4PB
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« Reply #14 on: November 16, 2017, 12:20:07 PM »

I wouldn't expect much static build up on a 2M ground plane with a 1/4 wavelength vertical element. Static build up problems usually occur with long, wire antennas such as HF dipoles.
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Bob  AA4PB
Garrisonville, VA
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