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 Post subject: LM386 transmiter and base loaded antenna
PostPosted: Apr Sat 14, 2018 1:54 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3939
Location: Cortez, Colorado
What do you have to change in the LM386 transmitter to connect it to a base loaded antenna.


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 Post subject: Re: LM386 transmiter and base loaded antenna
PostPosted: Apr Sat 14, 2018 5:41 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3660
You should be able to get a reasonable match by inserting a variable capacitor between the output of the LM386 transmitter and the base loaded coil. You may need to put an additional variable capacitor from the other side of the base loaded coil to ground.

In my case I had to put a capacitor from one of the lower taps to ground.

The component values depend on the operating frequency and the inductance of your base loaded coil. What is the inductance and frequency?


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 Post subject: Re: LM386 transmiter and base loaded antenna
PostPosted: Apr Sat 14, 2018 1:21 pm 
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Joined: Jun Tue 10, 2008 6:06 pm
Posts: 516
Location: San Antonio, TX
Just don't let the dog pee on the transmitter power supply :lol:

Dale


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 Post subject: Re: LM386 transmiter and base loaded antenna
PostPosted: Apr Sat 14, 2018 5:33 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3939
Location: Cortez, Colorado
Macrohenry wrote:
You should be able to get a reasonable match by inserting a variable capacitor between the output of the LM386 transmitter and the base loaded coil. You may need to put an additional variable capacitor from the other side of the base loaded coil to ground.

In my case I had to put a capacitor from one of the lower taps to ground.

The component values depend on the operating frequency and the inductance of your base loaded coil. What is the inductance and frequency?


I built 3 loading coils with a copper pipe for an antenna many years ago. Only finished one of them with a SStran 3000. I built Mike Toon's LM386 transmitter with a 1.228 Mhz crystal. I found that I have 4 variable capacitors, big tuning caps, that I got from AES 5 years ago. They look like thay were for AM/FM sets. So out of Mike's transmitter there is a 220uh coil to the antenna wire and a variable cap to ground.
Look at Mike's third post.
viewtopic.php?f=12&t=332195&p=2787483&hilit=mp3+ebay


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