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OT Antenna location concern

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Bill-3

OT Antenna location concern

I recently installed a Mitsubishi mini-split system and now have an
antenna concern. I am about to install a new dipole that will pass
within ten feet of one of the interior units (that would be measured
through the wall). I already know that the system has produced no
interference to any reception - however, I am concerned about how being
close to a transmitting antenna will effect or not effect the
unit/system. The antenna's location will meet safe human exposure limits
for the bands/power used - 160/75/40.

I am assured by the installer that RF is not a problem and not to be
concerned - of course that is not in writing. Attempts to email and call
Mitsubishi have not been informative. Hence my question:

Has anyone had difficulties with the control systems of their HVAC
systems caused by RF from a nearby transmitting antenna? I run the
KPA500 all the time - so consider this a 600 Watt station.

Thanks,

Bill W2BLC K-Line
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Don Wilhelm-4

Re: OT Antenna location concern

Bill,

All products are required to withstand RF susceptibility levels. So if
you encounter "strange happenings" with your HVAC system due to RF, the
supplier is bound to take corrective action.
Some may not understand, and some may not even know of the requirements,
so at worst case, you may have to get the FCC involved for resolution.
The most published FCC class B information regards radiation from the
device(s), but there is also regulations regarding susceptibility from
radiation from licensed services. The fact that you addressed the RF
interference situation with the installer should go a long way (document
that conversation for yourself with dates and names), and for a
reputable company should be as good as a written statement (I am no
lawyer, but it makes sense to me).

73,
Don W3FPR

On 8/14/2014 4:20 PM, W2BLC wrote:

> I recently installed a Mitsubishi mini-split system and now have an
> antenna concern. I am about to install a new dipole that will pass
> within ten feet of one of the interior units (that would be measured
> through the wall). I already know that the system has produced no
> interference to any reception - however, I am concerned about how
> being close to a transmitting antenna will effect or not effect the
> unit/system. The antenna's location will meet safe human exposure
> limits for the bands/power used - 160/75/40.
>
> I am assured by the installer that RF is not a problem and not to be
> concerned - of course that is not in writing. Attempts to email and
> call Mitsubishi have not been informative. Hence my question:
>
> Has anyone had difficulties with the control systems of their HVAC
> systems caused by RF from a nearby transmitting antenna? I run the
> KPA500 all the time - so consider this a 600 Watt station.
>

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Fred Townsend-2

Re: OT Antenna location concern

In reply to this post by Bill-3

Bill I'd like to add a few things to what Don has said. Fortunately the electronics in your HVAC system is fairly simply and easily shielded. However when susceptibly problems occur with Japanese designs it can be very difficult to get them to respond. Let's hope you don't have to go there.

What concerns me more is the noise/interference generated by some high SEER HVAC systems. These systems achieve variable speed by using variable frequency inverter driven motors. These can be a pain in two ways. First they radiate noise that can extend well above 160M. Second, they can induce harmonics on the powerlines. Line filters similar that what your kilowatt amps use are needed between the HVAC system and the 240vac power lines. Some of the HVAC systems have the filters built in and others don't. Let's hope they have done their homework and cleaned up their systems.

With your system operating in the AC mode you will want to scan 160M for noise or hash. You may want to check 80M too if 160M is dirty. Don't take acceptance of the system until it is proven clean.

73, Fred, AE6QL

-----Original Message-----

>From: Don Wilhelm <[hidden email]>
>Sent: Aug 14, 2014 4:54 PM,
>To: W2BLC <[hidden email]>, [hidden email]
>Subject: Re: [Elecraft] OT Antenna location concern
>
>Bill,
>
>All products are required to withstand RF susceptibility levels. So if
>you encounter "strange happenings" with your HVAC system due to RF, the
>supplier is bound to take corrective action.
>Some may not understand, and some may not even know of the requirements,
>so at worst case, you may have to get the FCC involved for resolution.
>The most published FCC class B information regards radiation from the
>device(s), but there is also regulations regarding susceptibility from
>radiation from licensed services. The fact that you addressed the RF
>interference situation with the installer should go a long way (document
>that conversation for yourself with dates and names), and for a
>reputable company should be as good as a written statement (I am no
>lawyer, but it makes sense to me).
>
>73,
>Don W3FPR
>
>On 8/14/2014 4:20 PM, W2BLC wrote:
>> I recently installed a Mitsubishi mini-split system and now have an
>> antenna concern. I am about to install a new dipole that will pass
>> within ten feet of one of the interior units (that would be measured
>> through the wall). I already know that the system has produced no
>> interference to any reception - however, I am concerned about how
>> being close to a transmitting antenna will effect or not effect the
>> unit/system. The antenna's location will meet safe human exposure
>> limits for the bands/power used - 160/75/40.
>>
>> I am assured by the installer that RF is not a problem and not to be
>> concerned - of course that is not in writing. Attempts to email and
>> call Mitsubishi have not been informative. Hence my question:
>>
>> Has anyone had difficulties with the control systems of their HVAC
>> systems caused by RF from a nearby transmitting antenna? I run the
>> KPA500 all the time - so consider this a 600 Watt station.
>>
>
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>Elecraft mailing list
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>This list hosted by: http://www.qsl.net
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Vic Rosenthal

Re: OT Antenna location concern

In reply to this post by Bill-3

I had intermittent problems with HF RF at the 100 to 1500 watt level on
various bands to my rooftop air conditioner unit. Antennas were a beam
about 30 feet above it and a vertical 20 feet away at roughly the same
height. I wrapped several turns of the cable to the thermostat around a
ferrite toroid which improved the situation but didn't totally fix it.
My unit had a 1960's technology circuit board in it, and I suppose newer
ones have microprocessors.
Ultimately the problem went away when I moved to a different country and
didn't take the a/c unit :-) , but I suppose it could have been fixed
with a better toroid and also perhaps a line filter.
I would always expect problems with electronic controls close to an
antenna, even with lower power.

On 8/14/14 11:20 PM, W2BLC wrote:
> Has anyone had difficulties with the control systems of their HVAC
> systems caused by RF from a nearby transmitting antenna? I run the
> KPA500 all the time - so consider this a 600 Watt station.

--
Vic, K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/
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Bill-3

Re: OT Antenna location concern

Most informative answers - in particular those from hams in the HVAC
business. Did not know there were standards to which devices must be
hardened and it is probably not needed that I even worry about it. They
appear to be well shielded from giving and receiving interference -
perhaps lessons learned along the way.

However, I have decided against installing the antenna in close
proximity to the mini-split anyway.

Thanks to all responding.

Bill W2BLC K-Line
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