Pos-150 - Electronic Circuits Projects Diagrams Free

savnik · 18th May 2007, 10:25 AM

I use POS-150 as oscillator for FM band (87.5-108 MHZ).
When modulate the oscillator with a MPX sound it plays well but does not make segregation in the channels , if I receive the oscillator with a stereo radio for Fm band. Only turn on the LED which is for to show when the station is stereo.
Why happen it ;

savnik · 19th May 2007, 01:00 PM

Anyone to have used the POS-150

**Nigel Goodwin** · 19th May 2007, 01:11 PM

As you don't even mention what it is?, and google doesn't find anything on the first page either, it seems a pretty vague question!.

JimB · 19th May 2007, 04:16 PM

Quote:

Originally Posted by savnik

I use POS-150 as oscillator for FM band (87.5-108 MHZ).

The POS-150 is a voltage controlled oscillator from Mini-Circuits.

Quote:

Originally Posted by savnik

When modulate the oscillator with a MPX sound it plays well but does not make segregation in the channels , if I receive the oscillator with a stereo radio for Fm band. Only turn on the LED which is for to show when the station is stereo.
Why happen it ;

It all depends what you mean by "MPX sound"?
I assume you mean a multiplex stereo signal.
How are you generating that multipexed signal?
Does it have the 38kHz (or is it 19khz?) pilot tone? If not the LED in the receiver won't illuminate.

JimB

savnik · 19th May 2007, 06:11 PM

Quote:

Originally Posted by JimB

The POS-150 is a voltage controlled oscillator from Mini-Circuits.

Yes

Quote:

Originally Posted by JimB

I assume you mean a multiplex stereo signal.
How are you generating that multipexed signal?
Does it have the 38kHz (or is it 19khz?) pilot tone? If not the LED in the receiver won't illuminate.

Yes , I mean a multiplex stereo signal and generate with stereo encoder( pilot tone is 19khz)

audioguru · 19th May 2007, 07:07 PM

Its modulation bandwidth is too narrow for FM stereo because it has an output down 3dB at 100kHz bandwidth. It must be absolutely flat to 38kHz for low audio frequencies stereo and it must be absolutely flat to 53kHz for audio frequencies up to 15kHz stereo.

It might work well for mono FM.

Here is a site "Stereo Multiplexing for Dummies" that explains it all:
http://members.tripod.com/~transmitters/stereo.htm

savnik · 19th May 2007, 07:36 PM

Quote:

Originally Posted by audioguru

Its modulation bandwidth is too narrow for FM stereo because it has an output down 3dB at 100kHz bandwidth.

3 dB MOD.
BANDWIDTH
(kHz)
100

Is from datasheet.Can you explain more to understand what mean;

**Nigel Goodwin** · 19th May 2007, 10:26 PM

FM stereo requires 300KHz bandwidth (if I recall correctly?), that's only got a third of what's required.

audioguru · 20th May 2007, 02:49 AM

In the "good old days" when an FM receiver's IF amplifier had a bandwidth that was too narrow for good separation of multiplexed stereo channels, an RC circuit was used in the audio path to boost the high frequencies up to 53kHz so that the response was flat. Then the stereo separation was very much improved.
I wonder how much it would help this RF transmitter.

savnik · 20th May 2007, 09:47 AM

Quote:

Originally Posted by Nigel Goodwin

FM stereo requires 300KHz bandwidth (if I recall correctly?), that's only got a third of what's required.

The FM bandwidth is 150 KHz

Quote:

Originally Posted by Nigel Goodwin

In the "good old days" when an FM receiver's IF amplifier had a bandwidth that was too narrow for good separation of multiplexed stereo channels, an RC circuit was used in the audio path to boost the high frequencies up to 53kHz so that the response was flat. Then the stereo separation was very much improved.
I wonder how much it would help this RF transmitter.

I don't believe to work , so i will try.

Lou Dorren · 18th September 2007, 02:59 AM

The mini circuits pos series of VCO can not be modulated by frequencies much over 10 KHz. This is because the is internally a large bypass capacitor (.1 uF) directly on the control voltage pin to ground. This is the reason you are having problems.

Lou Dorren

Hero999 · 18th September 2007, 09:02 AM

Thanks for posting but it's a bit late now as this thread is five months old.

chemelec · 18th August 2009, 09:53 PM

This is an Old Article, But I just purchased one of these "Mini-Circuits", POS-150 Modules.
(I Bought it On Sale for $4.00)

Talk about a Nice Chip for a Simple and Small FM Transmitter.
I'm Quite Impressed on its Frequency range (75 to 150 Mhz) and good Stability.

Haven't checked out What range I can get yet, But I will.

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18th May 2007, 10:25 AM	#1
savnik	Pos-150 I use POS-150 as oscillator for FM band (87.5-108 MHZ). When modulate the oscillator with a MPX sound it plays well but does not make segregation in the channels , if I receive the oscillator with a stereo radio for Fm band. Only turn on the LED which is for to show when the station is stereo. Why happen it ;

19th May 2007, 01:00 PM	#2
savnik	Anyone to have used the POS-150

19th May 2007, 01:11 PM	#3
Nigel Goodwin	As you don't even mention what it is?, and google doesn't find anything on the first page either, it seems a pretty vague question!. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

19th May 2007, 07:07 PM	#6
audioguru	Its modulation bandwidth is too narrow for FM stereo because it has an output down 3dB at 100kHz bandwidth. It must be absolutely flat to 38kHz for low audio frequencies stereo and it must be absolutely flat to 53kHz for audio frequencies up to 15kHz stereo. It might work well for mono FM. Here is a site "Stereo Multiplexing for Dummies" that explains it all: http://members.tripod.com/~transmitters/stereo.htm __________________ Uncle $crooge

19th May 2007, 10:26 PM	#8
Nigel Goodwin	FM stereo requires 300KHz bandwidth (if I recall correctly?), that's only got a third of what's required. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

20th May 2007, 02:49 AM	#9
audioguru	In the "good old days" when an FM receiver's IF amplifier had a bandwidth that was too narrow for good separation of multiplexed stereo channels, an RC circuit was used in the audio path to boost the high frequencies up to 53kHz so that the response was flat. Then the stereo separation was very much improved. I wonder how much it would help this RF transmitter. __________________ Uncle $crooge

18th September 2007, 02:59 AM	#11
Lou Dorren	The mini circuits pos series of VCO can not be modulated by frequencies much over 10 KHz. This is because the is internally a large bypass capacitor (.1 uF) directly on the control voltage pin to ground. This is the reason you are having problems. Lou Dorren

18th September 2007, 09:02 AM	#12
Hero999	Thanks for posting but it's a bit late now as this thread is five months old. __________________ I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong. Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

18th August 2009, 09:53 PM	#13
chemelec	Pos-150 This is an Old Article, But I just purchased one of these "Mini-Circuits", POS-150 Modules. (I Bought it On Sale for $4.00) Talk about a Nice Chip for a Simple and Small FM Transmitter. I'm Quite Impressed on its Frequency range (75 to 150 Mhz) and good Stability. Haven't checked out What range I can get yet, But I will. __________________ I No Longer accept Private Messages on here. All Emails to me Must Contain the Word \"Electronic\" in the \"Subject Line\" or they go Directly to my Junk Mail Folder. Email me at: chemelec@hotmail.com Website: http://www3.telus.net/chemelec