In order the troubleshoot the ALC problem, we need to understand the transmit chain. Without the overcurrent protection it provides, it’s easy to destroy the output transistors - difficult to find and expensive to replace. This is an excellent reason to use a Ten Tec power supply for testing a radio of unknown condition. This is normal with a matched load, but I also tried the radio on a random-wire antenna and should have seen some indication of the mismatch.Īlso, the ALC indicator didn’t light at all, and the radio would trip the over-current protection on a Ten Tec Model 262G power supply as I advanced the “Drive” control on the front panel. In the initial assessment, I noticed that the Signal Strength/SWR meter didn’t move during transmit. Troubleshooting the SWR Meter and ALC Light If you understand one of them, you can work on any of them. On the other hand, Ten Tec has used this transmitter scheme with only minor modifications for most of their radios - beginning with the Triton series. Although very reliable, it can be little tricky to troubleshoot.
Ten tec triton iv aux vfo driver#
This makes the transmit chain - from driver through finals and ALC circuitry - one big closed loop. The ALC also lit a visual indicator on the front panel when the transmitter reached the 100-watt maximum output. For protection, an “Automatic Level Control” (ALC) circuit provided negative feedback to reduce the transmitter’s output and provide a degree of signal processing. “Tuning” amounted to adjusting the drive to the final amplifier for maximum output without distortion or damage to the final transistors. This is commonplace today, but in 1973, it was revolutionary. Moreover, they were broadband - meaning the output amp could cover an entire amateur band without adjustment. By contrast, the Ten Tec 100-watt transceivers, starting with the Triton II, were fully solid state. In most early 70’s transmitters, one tuned the grid and dipped the plate of a vacuum tube-based output stage. įirst, a word about “tuning up” a Ten Tec transceiver. A Little Background on Ten Tec Solid State Transmitters. It had been quite a chase so far, and the remaining repairs would prove equally challenging. I could now receive and transmit signals in almost all the band switch positions, albeit with varying sensitivity and power output. In part one of this restoration, we tackled the two most glaring problems: garbled signals on receive and blowing fuses when the radio was switched to the 30-Meter band.