Birdie  Listener

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This is an Audio Project  that i have been  trying over the years that is not  to difficult  to do.

Using an op-amp  with a  high pass filter to filter out  low frequency noise. Be cause i live right to a busy road and that can be a pain in the ass.

Also it needed some form of cut off when there was no signal deteted

so was working on a squealch device a few years ago and re kindled my intrest  once again.

 So as you have  worked it out...is to listen to the birds when the sun goes down or rises..or other sounds in ones garden that the mic will pick up depending on the squealch setting.

The latest is a stereo one that uses only about 300 micro amp into an ear piece with no squealch so that it can be operated with a battery at about 9 volts and small caps value with a high quality op-amp the op group like Bur-Brown.

Also i have decided  to do a transmit  Audio listener with a small TX board for 88-108 MHz.  Iam using  this at this moment in time and the front end of ths transmitter need an preamp to it to make it more sentive to low level audio. Also ihave 3d printed a mounting  board that will hold the Battery/Tx unit...

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Tx Board and mount with battery holder.
This tx setup works very nice and when i have  some time to make up the  preamp board then get it made in China  to do in the autum .                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Top View
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VHF Dipole

I have been working on a  vhf  1/2  wave Dipole for this band and have nearly finished stage one in the design of.

Waiting for some high quality coax and some  cable to arrive  then i can test it and make adjustments  where needed. At this moment iam making  the 3d mount.
The antenna will be  suited for the  tx boards that have a 50 ohm output and this should  go a further distance

 
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These Inverted V  Dipole should have some gain over a quarter wave. More info... when constructed .
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Mounting:

Showing the mount and  other connecting  Hardware.
I have put a lot of time and effort into making this Antenna getting it to a low  vswr  as one will see in the next Pic.
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Antenna mounted on some  Bamboo Canes wich is ideal for adjusting to the correct angle
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This Antenna is for txing on Fm  Vhf band   87-108 ish part of  of the spectrum .

The elements use quite some thick copper wire and i think this should be good up to a 100 watts of power.


Iam hoping  to recive a 5 watt Transmitter from china  soon and do a final test before i sell them on ebay for about £18.  each...What a bargain .   10/07/2021.  

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Reading on my  nano vna Meter

With a vswr of  1.09   @  about 108 Mhz that is a good low value to be at.
Beautiful Landscape