Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
How to add an RF protection device to amplifier?

The AM Forum
April 16, 2021, 10:24:18 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: 1 [2]   Go Down
Author Topic: How to add an RF protection device to amplifier?  (Read 11349 times)
0 Members and 1 Guest are viewing this topic.

Offline Offline

Posts: 239


« Reply #25 on: March 17, 2011, 08:06:54 PM »

You still have a problem. Steve's board is a wonderful circuit but as I recall is tracks the current vs. voltage from the modulator stage. If either one falls out of the comparator window the circuit "trips".  I suppose you could compare final PA current to a non-varying reference voltage if you reduced the sensitivity of the comparator. A question Steve could easily resolve.

But you still need a way of detecting the reflected power and something for either condition to act upon to shut-r-down.  Speaking of "r". Did you name this contraption yet? 

Offline Offline

Posts: 8514

"Let's go kayaking, Tommy!" - Yaz

« Reply #26 on: March 17, 2011, 08:31:11 PM »


Good point about the current vs: voltage tracking.   Yes, maybe if the Voltage is set to a certain threshold value, the current will hit the desired preset point and trigger the comparator. I think that wud work, but Steve wud know for sure.  I need a trigger at above 10A at 30V.

The LP Filter has a reflected SWR output, so I'm all set there.

I plan to use the overload hi or lo to trigger a SS device to shut down the amplifier bias or PTT circuit voltage.  No relays involved.


Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
Pages: 1 [2]   Go Up
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.059 seconds with 19 queries.