[RFI] Multi-Stage High Efficiency Air Conditioner Units

[Kim Elmore]

My understanding is that the RFI is generated by the variable speed 
motor controls. In these systems, both the compressor and the forced-air 
run at variable speeds. Which is the main contributor to the RFI? These 
units will be maybe 30 ft from my tower; I shunt-feed my tower for 160 
m, so they will be in a relatively high RF environment.

*IF* we replace our current units (and that's a *very* big if), I'll 
make sure that the thermostat line is also filtered one way or the other!

Kim N5OP

On 2/7/2020 3:44 PM, Jim Brown wrote:
> On 2/7/2020 1:11 PM, krgoodwin at comcast.net wrote:
>> The culprit was the thermostat line
>> (4-conductor) where installing an RF filter (LC circuit) on each of 
>> the four
>> conductors in addition to some ferrites on the line easily solved the
>> problem.  Next re-install I will put in a shielded multi-conductor
>> thermostat control line which was my baseline for the house LAN 
>> (shielded
>> ethernet line).  Shielded cat XX (ethernet) line costs more but I 
>> think the
>> cost is worth it since my tower/beam is right next to the house
>
>
-- 

Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP 
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)

/"A great second violinist plays second fiddle to no one." //– Robert C. 
Marsh, Chicago Sun-Times./