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Search found 10 matches
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Topic: Humm!
seven

Replies: 7
Views: 6898
PostForum: Schematics - help and ideas   Posted: Thu Jan 10, 2008 5:03 am   Subject: Humm!
One thing, it is best to place amp and exciter in separate boxes. This is why all major
big-power transmitters are always separated above, say 200-500W of power.
Yeh i would do if it was that kind o ...
Topic: Humm!
seven

Replies: 7
Views: 6898
PostForum: Schematics - help and ideas   Posted: Tue Jan 08, 2008 8:12 pm   Subject: Humm!
Just tested it properly. There is still some hum there but not as much.
However, when i power the exciter with my bench PSU and run the rest as normal there is no humm atall so the problem lies in t ...
Topic: Humm!
seven

Replies: 7
Views: 6898
PostForum: Schematics - help and ideas   Posted: Tue Jan 08, 2008 5:39 pm   Subject: Humm!
I think ive done it!

A ground loop i belive (you may be able to verify)


Took me a while to find it but i fixed it by just connecting the negative of the rectifier straight to ...
Topic: Humm!
seven

Replies: 7
Views: 6898
PostForum: Schematics - help and ideas   Posted: Tue Jan 08, 2008 4:28 am   Subject: Humm!
Ok i am using one of the 150w amps (BW do them aswell i think) and just a standard PLL driver (500mw-1w)

I have boxed it all up and all is working fine but i get a hummmmm when i turn the radio up ...
Topic: Help with SWR protection circuit
seven

Replies: 8
Views: 8899
PostForum: Schematics - help and ideas   Posted: Tue Jan 08, 2008 2:33 am   Subject: Help with SWR protection circuit
Thanks Marko, this seems to work fine.
Topic: FM Transmitter Setttings? Dip Switch
seven

Replies: 5
Views: 6708
PostForum: Users share experience...   Posted: Sun Dec 30, 2007 6:02 pm   Subject: FM Transmitter Setttings? Dip Switch
Have you got a pic of the board? im not sure if its the one im thinking of
Topic: Help with SWR protection circuit
seven

Replies: 8
Views: 8899
PostForum: Schematics - help and ideas   Posted: Sun Dec 30, 2007 5:34 pm   Subject: Help with SWR protection circuit
This is the bias circuit to the base of the BLF244:

http://i52.photobucket.com/albums/g38/prime106/bias.jpg
Topic: Help with SWR protection circuit
seven

Replies: 8
Views: 8899
PostForum: Schematics - help and ideas   Posted: Sun Dec 30, 2007 3:48 pm   Subject: Help with SWR protection circuit
I already have the SWR pickup strip which goes low when the SWR gets high . Im just not sure how to use it to pull the bias voltage down, where to connect it on the bias circuit etc. I cant just short ...
Topic: Help with SWR protection circuit
seven

Replies: 8
Views: 8899
PostForum: Schematics - help and ideas   Posted: Sun Dec 30, 2007 2:57 pm   Subject: Help with SWR protection circuit
Either works well. Pulling the bias voltage down or cutting off the drive.

Just make sure your amplifier is stable with exciter output turned off, especially
if it still produces small amount of p ...
Topic: Help with SWR protection circuit
seven

Replies: 8
Views: 8899
PostForum: Schematics - help and ideas   Posted: Sat Dec 29, 2007 4:15 pm   Subject: Help with SWR protection circuit
Whats the best way to incorporate this on a band 2 amplifier?

Anyone got any schematics or docs handy?

is it best to just turn down/off the bias supply to the driver transistor (im using blf244 ...
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