UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Other Discussions > Homebrew Equipment

Notices

Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members.

Reply
 
Thread Tools
Old 19th Jul 2019, 3:36 pm   #1
Wendymott
Heptode
 
Wendymott's Avatar
 
Join Date: Jun 2013
Location: Huddersfield, West Yorkshire, UK.
Posts: 938
Smile Tuning up a SSB TX

Hi peeps. The saga continues..My homebrew 3 band SSB transceiver.
Should I include a sinewave AF oscillator to modulate the TX at low power to tune the ATU Match, and if I want to join a "QSO" how far away from the QSO should I frequency shift so I dont cause interference to the QSO.
Thanks
__________________
Should get out more.

Regards
Wendy G8BZY
Wendymott is offline   Reply With Quote
Old 19th Jul 2019, 4:05 pm   #2
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 7,400
Default Re: Tuning up a SSB TX

Rather than adding a separate oscillator the usual way to produce a whiff of RF is by unbalancing the balanced-modulator. If it's a diode type, putting a bit of DC through one half achieves this - all you need is a pot and a RF choke.

As to tuning-up techniques - there are ways to do this which involve radiating spectacularly-little power (using a resistive bridge, a detector and a microammeter) so you don't really need to worry about 'ofsetting' your frequency.

See http://www.zerobeat.net/g3ycc/res_swr.htm for example. I've got something similar here and it works fine on 5MHz when driven by a BC109 crystal-oscillator running from 12V.
G6Tanuki is online now   Reply With Quote
Old 19th Jul 2019, 5:08 pm   #3
Wendymott
Heptode
 
Wendymott's Avatar
 
Join Date: Jun 2013
Location: Huddersfield, West Yorkshire, UK.
Posts: 938
Default Re: Tuning up a SSB TX

Hi Tanuki.. The modulator is a MC1496, with a balance pot, so I can offset the trim pot.

Thanks for the tuning up info. As it happens the PA has just "died" again.. Grrrrrrrrrrrrrrr
__________________
Should get out more.

Regards
Wendy G8BZY
Wendymott is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 3:22 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.