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eHam Forums => SWL (Shortwave Listening) => Topic started by: WA4053SWL on June 24, 2012, 09:47:03 AM



Title: Collins 75s3 Anti-Vox jack question
Post by: WA4053SWL on June 24, 2012, 09:47:03 AM
Hello all,
Recently bought this receiver and it works great, I was listening a few minutes ago a CW contest on 15 meters, was connected to a high impedance speaker LS445/U, when changing the speaker to anti-vox jack listen much better and stronger, this is because the "anti-vox" jack is high impedance output??.
Another question I wanted to make, this receiver has no installed 200 hz CW filter, can put one of 500 hz??.
Thank you all for any reply.
73 George ;D


Title: RE: Collins 75s3 Anti-Vox jack question
Post by: AA4PB on June 24, 2012, 01:55:44 PM
The anti-vox output is 500 Ohm so it may provide a bettery match to your speaker.

You can use a 500Hz filter **IF** it is designed to be used in a 75S3. The filter has to be the correct frequency and impedance to work with the receiver design.


Title: RE: Collins 75s3 Anti-Vox jack question
Post by: WA4053SWL on June 25, 2012, 08:39:22 AM
Ok, thank you sir for your kind response, the high impedance speaker sounds great, and I can get a 500 hz filter to put there.
Have a nice day.


Title: RE: Collins 75s3 Anti-Vox jack question
Post by: KA5N on June 25, 2012, 05:48:22 PM
iNTERNATIONAL RADIO INC (IRAD)  makes  300KHZ and  500KHZ for your receiver, which
plug in.  You will have to be sure that your receiver has the correct BFO crystal.  While you can receive CW with a SSB BFO crystal  it would put the signal outside the filter passband.
Do a search for INRAD and download the PDF catalog.  The prices aren't in the catalog but
the filters run around $300-$400.

Allen KA5N