• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
  • Notice: You may not use this site to facilitate the unauthorized selling of copyrighted material including, but not limited to, in the public dxForums, dxGallery, dxChat and private messsages. If you get caught doing this, you will be permanently banned with no second chances. A notice will be placed on the site of why you were banned and any information collected by this site about you will be made known to the copyright holder.

Courier ML100 for SSB


Dmans

Sr. Member
Jan 22, 2017
1,265
1,534
173
Georgia
This is a strange schematic. The more I look at it the less I am sure it is correct. It appears the RF keying circuit is energizing relay coil "K2" but the only contacts listed for Relay "K2" would supply the high voltage to the tube anodes. Yet the K1 relay would switch Rf from "straight through" to "Amplified" power but appears to be driven by the chopper transistors (Q4 & Q5). If that were correct your delay capacitor would be C13. Try increasing it from 10uF to 100uF.

73
David
 

DoctorAudio

Well-Known Member
Sep 11, 2009
150
204
53
The combination of C13, R7 and R8 set the oscillation frequency and base bias of the inverter transistors, don't mess with C13.
 

nomadradio

Analog Retentive
Apr 3, 2005
5,207
7,395
573
Louisville, KY
www.nomadradio.com
I think CR1 is drawn backwards. Should have the anode grounded, not the cathode as shown.

Making C3 bigger should produce a delay, with a switch on it to select AM.

Bear in mind the tubes are wired with zero grid bias. In AM, the radio's carrier reduces the tube's DC current below what it would be with no RF drive power. Unless you come up with a source of negative bias for the tubes' grids, or a zener in line with the cathodes you'll find the tube's anodes overheating, "cherrying" when using sideband.

Looks as if they left off the sideband switch so they wouldn't have to spend money making it actually survive using it that way.

73
 

AxlMyk

Member
Feb 21, 2022
38
52
18
The Hartland of Michigan
I'll check CR1 when I look at it again. It does seem strange for it to be that way.
This amp does kick out some power. 75-80 watts AM or SSB. I haven't noticed any over heating, but it hasn't been keyed long during testing. SWR between radio and amp is below 1.5:1. Not bad for $20.
 

dxChat
Help Users
  • No one is chatting at the moment.