[Lowfer] wireless doorbells

[Douglas D. Williams]

Good info, thanks. Guess I'll be going wireless. Time to build a bridge to
the 21st century!

D.

On Sat, Aug 27, 2011 at 12:56 PM, Dexter W4DEX <dexter.mc at gmail.com> wrote:

> Douglas D. Williams wrote:
> > Well, my (unknown age) doorbell finally bit the dust. It's the old wired
> > style with the bell in the hallway and the transformer in the attic. I
> may
> > just replace it with one of the newer wireless models. I assume they
> operate
> > on a Part 15 frequency. Anyone know if I am apt to experience any QRM
> issues
> > on LF? Does the button only transmit when pressed?
> >
> >
> Most of those type license free devices work on UHF so it's very
> unlikely to make any noise on LF.  I saw one type that had two way
> intercom which operated on 900 MHz.  Other common frequencies for
> consumer wireless devices are 315 and 433 MHz.  Yes, right in the 70 CM
> ham band!  If I tune between 433.5 and 434.5 I hear multiple wireless
> thermometers and other devices from miles away.  But that is with a high
> gain antenna and a low noise figure preamp.  Fortunately these devices
> haven't caused me any problem on the primarily weak signal frequency of
> 432.100 +/- a hundred kHz or so.
>
> Dex
>
> BTW, I have see very old doorbell transformers generate LF noise.  I
> assume when they start arcing internally.
>
>
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