I have this amp and want to delay the relays for SSB use. Here is the schematic.
My skills have become rusty after a few decades. Looking for some guidance.
My skills have become rusty after a few decades. Looking for some guidance.
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Courier ML100 for SSB
- Thread starter AxlMyk
- Start date
That's what I was thinking.
I put a 10mfd in parallel, but it keys when I turn it on. I don't understand why, so I removed it. I'll try a 5mfd for 15 total.
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
73
David
The combination of C13, R7 and R8 set the oscillation frequency and base bias of the inverter transistors, don't mess with C13.
I Found a service manual that addresses chatter with SSB.
C18 open
C14 or Q1 defective
Low voltage
C18 open
C14 or Q1 defective
Low voltage
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
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
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.
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.
CR1 is indeed backwards on the schematic.
I have some capacitors on the way. I'll mess with it when I find time in my busy, retired life.
I have some capacitors on the way. I'll mess with it when I find time in my busy, retired life.
I decided to put this thing away for some other time. Not much of it relates to the schematic, but it does pump out 100 watts on am/ssb. I've tried several capacitors in a few places and it makes no difference.
I purchased an RK 203p that does a fine job, and mounts to the top of the radio with a magnetic sheet from my 3d printer. No holes in the radio.
I purchased an RK 203p that does a fine job, and mounts to the top of the radio with a magnetic sheet from my 3d printer. No holes in the radio.