• 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.

Search results

  1. A

    EB63 amp adapted for 2SC2879

    I guess I'm still the only one who has attempted this. Since the last post, I changed the C-E capacitors to 120pf and added 2 attenuators. I also beefed up the power wires and a few other minor changes. I added a relay to the bias resistor. I tried a higher input and got up to 350W on the PEP...
  2. A

    EB63 amp adapted for 2SC2879

    OK. I reduced the bias to .5A and took out 1 turn of the output transformer. Now it will deadkey 50W and peak at 225. I tried a 3db pi attenuator and it deadkeys 50W and peaks at 175 with a 4W input. Not bad.
  3. A

    EB63 amp adapted for 2SC2879

    I already have it assembled from many years ago. It actually does work but with less power than expected. I'll take a look on the oscilloscope but my meter says 175W PEP. On AM, that is with a 70W carrier. In other words, the peak power is not 4 times the unmodulated power. The bias is a little...
  4. A

    EB63 amp adapted for 2SC2879

    https://www.communication-concepts.com/content/EB63A/Original_EB63_Engineering_Bulletin.pdf
  5. A

    EB63 amp adapted for 2SC2879

    This is a project I started years ago. The EB63 kit was made by Communication Concepts and uses MRF454. I thought I might reference the Texas Star amps for parts changes. I got out of radio and never finished it. Any help is appreciated.
  6. A

    President Lincoln II Plus blown finals and regulator

    It's not actually the regulator but a series pass transistor. It is shorted base to collector causing it to be fully on. The good news is that the base voltage changes like it should with that transistor removed. Got the TIP36C on order. We wait.
  7. A

    President Lincoln II Plus blown finals and regulator

    I have a Lincoln 2 plus with blown final MOSFETS. After replacing the finals, the RF Power knob has no effect. The AM carrier is close to 50 Watts. I believe Q55, a series pass transistor that feeds the finals is shorted. Is this something that happens often?
  8. A

    President Lincoln 2+ v3 Adjustment Location Indentification?

    I would like to know how you did the High Drive modification.
  9. A

    RM KL203-P

    Here is my 1/2 power mod on a KL203 (not the P) The input trace from the relay to the transformer is cut. An 18 ohm 3W resistor is in series. On either side of the 18 ohm resistor is a 300 ohm 1W resistor to ground. This gives a deadkey around 30W from a stock 4W radio. It was 60W before this...
  10. A

    RM KL203-P

    I received my order yesterday. I tried ferrites on power and coax cables with no change. The 30Mhz low pass filter did the trick. SWR with the amp on is good on all 40 channels.
  11. A

    RM KL203-P

    I would love to know what the power output is with the 13n10 replacements. I added an attenuator to mine. It's a pi attenuator that cuts the input in half. My meter won't measure peak or PEP correctly but the deadkey is 30W with 4W input. I'm still having issues with oscillation but I think the...
  12. A

    RM KL203-P

    I also noticed there is a 180pf capacitor in series with the output. That's a reactance of 32 ohms at 27 MHz Doesn't make much sense to me.
  13. A

    RM KL203-P

    Thanks for the calculator. I have a President Bill that will probably be mounted in the car. I might also use an RCI 2950 or a JCPenney 6247 when I get them working. The bigger radios would be temporary hookups for DX when I'm by myself. I know it's easy to adjust the President Bill. I still...
  14. A

    RM KL203-P

    I know this thread has a little age on it but did anyone ever manage to mod this amp to accept higher power? I'm trying to avoid lowering the radio's power. The amp won't always be on and I might use it with different radios, all of which have 4 watts and barely above stock modulation. On the 2...