btw it use sd1407 according to datasheet it is up to 30 mhz how do that not eg 175 mhz
BW
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radium98
- proppa neck!
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BW
can you help me with the manual or components of this warehouse 100w pa fm
btw it use sd1407 according to datasheet it is up to 30 mhz how do that not eg 175 mhz
btw it use sd1407 according to datasheet it is up to 30 mhz how do that not eg 175 mhz
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Albert H
- proppa neck!
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Re: BW
The SD1407 gives useful gain up to around 140MHz. Many transistors specified for use at lower frequencies will actually prove useful at VHF (though many others won't!).
Back in the early 80s, Birkett's in Lincoln was selling a stud-mount device called a 587BLY. They claimed that they were good to 30 MHz. After a bit of experimentation, I found that I could run them at 28 - 30V supply, drive them with a 2N3375 and get around 90 Watts (at least) for 1 Watt of drive. The pre-drive transistor was usually a 2N3866 - which will also work nicely (with plenty of gain) at 28 - 30V. I came up with a nice little PA PCB with three trimmer caps on it (one for each stage) that fitted a cheaply available heatsink. My whole PA cost about £12 if you made your own output filter capacitors - the output device was £3, the driver was 75p and the pre-driver was 60p. The heatsink was the most expensive part! In those days - with a much quieter band - 90 Watts would cover most of London.
I negotiated a deal with Birkett ( for a lot less than £3 each!) and got in huge stocks of materials to turn out these PAs. In the end, I must have shipped about a thousand of them. They went all over the world! The little exciter that drove them (a four stage job giving 100mW) was also put on to a PCB, with the synthesiser parts on one side and the RF strip on the other.
A New York-based pirate showed me how they built their PAs out of audio FETs because they couldn't easily get RF power devices. They would use eight paralleled devices, and the gain wasn't spectacular, but they were getting 50 Watts out of $4-worth of transistors!
Back in the early 80s, Birkett's in Lincoln was selling a stud-mount device called a 587BLY. They claimed that they were good to 30 MHz. After a bit of experimentation, I found that I could run them at 28 - 30V supply, drive them with a 2N3375 and get around 90 Watts (at least) for 1 Watt of drive. The pre-drive transistor was usually a 2N3866 - which will also work nicely (with plenty of gain) at 28 - 30V. I came up with a nice little PA PCB with three trimmer caps on it (one for each stage) that fitted a cheaply available heatsink. My whole PA cost about £12 if you made your own output filter capacitors - the output device was £3, the driver was 75p and the pre-driver was 60p. The heatsink was the most expensive part! In those days - with a much quieter band - 90 Watts would cover most of London.
I negotiated a deal with Birkett ( for a lot less than £3 each!) and got in huge stocks of materials to turn out these PAs. In the end, I must have shipped about a thousand of them. They went all over the world! The little exciter that drove them (a four stage job giving 100mW) was also put on to a PCB, with the synthesiser parts on one side and the RF strip on the other.
A New York-based pirate showed me how they built their PAs out of audio FETs because they couldn't easily get RF power devices. They would use eight paralleled devices, and the gain wasn't spectacular, but they were getting 50 Watts out of $4-worth of transistors!
"Why is my rig humming?"
"Because it doesn't know the words!"
"Because it doesn't know the words!"
what do u think -
yellowbeard
- tower block dreamin
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Re: BW
Is this it?
Code: Select all
http://gbppr.dyndns.org/~gbpprorg/lpfm/bw150free.zip-
yellowbeard
- tower block dreamin
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Re: BW
Looks the mostly the same. I haven't been able to edit that website since 2003 or thereabouts, the webspace was from an ISP from the days of dial-up, surprised it is still running TBH.
