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post #1 of 14 (permalink) Old 2017-02-24, 06:18 PM Thread Starter
 
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Hair Dryer?

Why does my wife's hair dryer kill the signal of CFTO on RF 9.
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post #2 of 14 (permalink) Old 2017-02-24, 07:23 PM
 
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Because it's putting out excessive electrical noise which usually hits the lower frequency and weaker (VHF) channels first.

With digital reception, it's always about the ratio of the desired to the undesired signal within the occupied channel's bandwidth. The signal from the broadcast tower is the desired signal. Anything else within that channel's bandwidth that is not the desired signal is noise. When the ratio of the power of the noise exceeds the power of the desired signal at the tuner's front end by the SNR required for reception, then reception fails.
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post #3 of 14 (permalink) Old 2017-02-25, 01:11 AM
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There are two different types of Electrical Motors: Brush Type [which are spark gap transmitters, used in the CHEAPEST Hair Blowers] and Brushless [which generate much less Interference but costs more]. [BTW: The term "AC Motor" is ambiguous...could be either type.]

I'm no expert on Hair Blower Selection, but here are some of the least expensive Brushless types, with many in the $100-200+ range, incl. the pricey Dyson:
https://www.amazon.com/Infiniti-Cona.../dp/B00MO78Z86
Target : Expect More. Pay Less.
The "Ionic" Feature MAY or MAY NOT be a secondary Interference Source....I just don't know....but she should be able to switch it ON and OFF.

Adding an EMI/RFI Filter will likely suppress at least SOME of the Interference generated by a Brush Type Motor. You could start by surrounding the Hair Blower's Power Cord with a suitably sized Wrap-Around FERRITE CORE, such as fol., preferably located as close to Dryer as possible....and perhaps a second near the Power Plug:
https://www.amazon.com/Ferrite-YAMAY.../dp/B01MDUT7PW

For Additional Suppression [in ADDITION to Ferrite Core], an external Power Strip/Surge Protector with EMI/RFI Filters, such as fol. MAY or MAY NOT provide sufficient Interference suppression [just a few examples of typical offerings...however MOST Power Strip/Surge Protectors do NOT have any RFI/EMI Filters]. Note that last two are Auto-Switching Master/Slave type:
https://www.amazon.com/Belkin-BE1060.../dp/B003OBSN7Y [Up To 43 dB Suppression]
http://static.highspeedbackbone.net/...ta%20Sheet.pdf
https://www.amazon.com/Tripp-Lite-Ec...003A816FM?th=1 [Up To 40 dB Suppression]
https://www.amazon.com/Smart-Strip-S.../dp/B000P1QJXQ [Up To 52 dB Suppression]

Alternatively, for the MOST Suppression [in ADDITION to Ferrite Core], an external EMI/RFI Filter, such as Tripplite Iso-Blok [conveniently plugs into existing AC Socket] or Iso-Bar [various Power Strip configurations are available] provide an outstanding 40-80 dB of Interference Suppression:
https://www.amazon.com/Tripp-Lite-Is.../dp/B00XDC4IQO
https://www.tripplite.com/shared/pro.../ISOBLOK20.pdf
https://www.amazon.com/Tripp-Lite-Pr.../dp/B0000510Z9
https://www.tripplite.com/shared/pro...N/ISOBAR26.pdf

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2017-02-25 at 03:04 AM.
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post #4 of 14 (permalink) Old 2017-02-25, 10:24 AM
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I would be cautious about using a power bar or plug type RFI filter with a hair dryer. Hair dryers can draw 1500w or more which may overload a power bar or RFI filter, especially if other devices are also plugged in. I've seen RF filters that were rated for as little as 600w. Like any high power device, hair dryers should be plugged directly into the outlet. In this case, a better hair dryer would be a much better solution.
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post #5 of 14 (permalink) Old 2017-02-25, 11:57 AM
 
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VHF Reception-Electrical Noise

Unfortunately VHF ASTC 1.0 reception is highly vulnerable to electrical noise under weak signal conditions.With CFTO at 10kw watts does not leave much margin for noise beyond 30 miles.Get used to it atleast 1 Buffalo station is switching back to VHF.

Attic CM 4248 at Buffalo,M4 at Buffalo.VHF yagis at Toronto .
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post #6 of 14 (permalink) Old 2017-02-25, 11:57 AM
 
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Quote:
In this case, a better hair dryer would be a much better solution.
Yep. i wouldn't even bother with any of the filtering ideas anyway. The most likely point-source of the electrical interference is at or in the motor itself with the noise being radiated directly from that point. Therefore any sort of filter on the power line would not be effective.

Here's my usual list of things that have the known potential to actually solve the problem, they all involve the improvement of reception of the desired signal while minimizing the reception of the noise, thus improving the SNR on the problem channel.

A. Relocate or re-orient the receiving antenna to a spot that maximizes the desired signal while minimizing the noise. A lot of this is dependent on how your home is laid out and where the hair dryer is used relative to where the antenna is currently situated. Generally, getting your antenna as far away from the source of the noise is the idea as the power level of the noise will drop inversely with the square of the distance.

B. Use a VHF antenna with higher gain. An antenna of this type will offer greater rejection of signals outside of its reception aperture when compared to, for example, a simple dipole. You didn't tell us anything about what antenna you're using.

C. Buy and try new hair dryers and see what doesn't cause interference in the first place. A higher quality unit is perhaps the best idea in this category.

Good luck.....
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post #7 of 14 (permalink) Old 2017-02-25, 01:58 PM
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If it bothered me enough, I would tell my wife her hair dryer wasn't safe anymore.
She would believe me and buy a new one.
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post #8 of 14 (permalink) Old 2017-02-25, 02:19 PM
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Since the Hair Blower's POWER CORD is the VHF Antenna for RADIATED Emissions, Ferrite EMI Suppressors should be fairly effective...and even better with one at either end of the Power Cord [and since they seem to come in packs of 10....why not one or more along it's length]. And external EMI/RFI Filters Suppress the CONDUCTED Emissions. But I think buying a new Brushless Hair Blower is the best first step.....

Except for the Tripplite ISOBAR series (1440 Watts), all of the other Surge Protectors with EMI/RFI Filters I cited above are rated for 15 A (about 1800 Watts). If you are contemplating buying a Hair Blower that draws significantly more than 1800 Watts, you're going to need a 20 A Circuit [with AWG10 Wiring per NEC Code].....which is fairly rare, except perhaps in the Kitchen....or some newer homes.

Conair 3Q advertises that their Hair Blower is better than another 2000 W Professional Hair Blower....but fails to advertise the ACTUAL Wattage Rating. User Manual indicates that it is 1875 Watts and will work on a 15 A Electrical Circuit. So it has been INTENTIONALLY designed to work right at the limit of a 15 A Circuit....and they advise NOT operating ANYTHING ELSE on that circuit when operating the Hair Blower [such as a Curling Iron]:
https://www.conair.com/assets/files/...r-dryer-ib.pdf
Perhaps this sort of thing should be taught in JUNIOR HIGH SCHOOL as part of their required HEALTH Class. I know that one of my girls was rudely made aware of certain "limitations" when she was a Teenager, forced to run back and forth between her bedroom and the bathroom. And my wife has learned to NOT operate the Microwave, Toaster and Electric Skillet on HIGH at the same time [Keurig Coffee Maker is on a separate circuit].

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2017-02-25 at 02:48 PM.
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post #9 of 14 (permalink) Old 2017-02-25, 10:39 PM
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I've got to wonder why the Microwave, Toaster and Electric Skillet are on the same circuit. Electrical code here requires that kitchen and dining room outlets be fed with 2 separate circuits. That way, breakers do not get overloaded unless a power tap or power bar is used and that is not recommended. It might be a good idea for bathroom vanity plugs to be on a separate circuit as well. In any event, the use of a power bar near a kitchen or bathroom sink is a bad idea for more than one reason.

If an appliance is emitting too much RFI, the best course of action is to replace it. It's either cheaply made, in which case it's not much of a loss, or defective, in which case it should definitely be replaced.
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post #10 of 14 (permalink) Old 2017-02-26, 07:36 AM
 
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Remember that episode of "Green Acres" where Oliver was trying to teach Lisa about what the generator could supply and what combinations of loads could be used at any given time?
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post #11 of 14 (permalink) Old 2017-02-26, 09:15 AM
 
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Are absolutely sure it happens only with your wife's hair dryer? nothing else?

It sure sound strange to me.
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post #12 of 14 (permalink) Old 2017-02-26, 09:49 AM
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It's not strange at all. I've seen various RF sources, small motors especially, interfere with radio and TV signals many times. Switch arcing on everything from lights to furnaces and refrigerators can do the same. Changes to technology, implementing RF suppression in noise generating appliances and direct wiring such as cable TV have minimized the impact. In this case, it appears that the makers of the hair dryer made no effort to suppress RF emissions. The solution could be as simple as placing a small capacitor across the motor connections. I wouldn't recommend trying to retrofit it though.
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post #13 of 14 (permalink) Old 2017-02-26, 04:40 PM
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Quote:
Originally Posted by ExDilbert View Post
I've got to wonder why the Microwave, Toaster and Electric Skillet are on the same circuit. Electrical code here requires that kitchen and dining room outlets be fed with 2 separate circuits. That way, breakers do not get overloaded unless a power tap or power bar is used and that is not recommended. It might be a good idea for bathroom vanity plugs to be on a separate circuit as well. In any event, the use of a power bar near a kitchen or bathroom sink is a bad idea for more than one reason.

If an appliance is emitting too much RFI, the best course of action is to replace it. It's either cheaply made, in which case it's not much of a loss, or defective, in which case it should definitely be replaced.
WTMI: Kitchen is indeed fed with at least TWO different Circuits [actually FOUR with Sharing]....however 15A Circuit on the LEFT side of the Stove [1 outlet for Tiny 18-in Counter Top, another above Stove for Exhaust] can only feed Keurig and Exhaust Fan over Stove with NO ROOM left for any other appliance, while Circuit on the RIGHT side of the Stove [1 Outlet behind Microwave Cubby and Only 1 Double Outlet for Appliances....so lots of cord swaps] feeds EVERYTHING else on the remaining 6-ft of Counter Top before reaching Sink. TWO other Circuits feed different Outlets in DR, one shared with Total 240 W Overhead Fluorescents in Kitchen [I think this year I'll upgrade to LED Tubes] and 1000-W Skillets [2 ea] or Electric Wok when we cook Japanese Food at the DR Table. The other DR Circuit is shared with FR Add-On [with wife's old TUBE TV she refuses to give up and my two Overclocked Desktops and new Window A/C]....and then Disposal, Sink Light and Pair of 100W Outdoor Halogen Floodlights for Gas BBQ....have to be very careful when I turn on the Oil Filled Electric Heater for those 10 days a year it gets down to Freezing [and Heater Vent to Add-On is WAY TOO SMALL, even after I added some 12 VDC "Helper" Fans].

Home built in 1973, Kitchen Reworked + FR Add-on about 1980. I once had a Power Strip mounted under the Top Cupboards and I COULD cut out some Tile and upgrade to Quad Outlet....but my wife would STILL insist on disconnecting Appliance Cords, cuz she thinks it's "Safer".....and LIMITS how many Large Skillets (Family meals sometimes need TWO) or Large Crock Pots (THREE for St Paddy's Day Corned Beef & Cabbage, one in front of Keurig) and whatever else she needs.....so why bother....ensures very few trips outside to reset the Circuit Breaker.

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2017-02-26 at 05:07 PM.
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post #14 of 14 (permalink) Old 2017-02-28, 02:07 AM
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If it is causing much trouble then it's better to purchase a new one. I think that would be the better option.
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