Here's yet another relay substitution. This time it's not so much the relay itself that's the reason, but where it's located. The Texas Star DX1600 has eight 2SC2879 transistors, arranged as four push-pull pairs. Texas Star uses four of the circuit board found in their smaller amplifiers, splits the drive power and then combines what comes out of each pair. The relay that actually switches the antenna circuit is a lot bigger than what's used in their smaller models.
The circuit board holes where the relay will mount is empty in the front-most three circuit boards. The rear-most of the four has the keying transistor and relay found in the smaller models, but it serves only to switch 12 Volts DC when the mike is keyed. The output from this small relay splits off in two directions. First, to activate the coil in the large antenna relay, and second to supply base-bias current to the "R10" 25-ohm 5 Watt resistor on each of the four pc boards.
This amplifier had the heaviest-duty version of this small "R10"-size relay they sell, but still hesitated to close the circuit and trip the big relay. Removing the rear-most of the four circuit boards where this relay lives looked too much like an act of congress. So I took the sharpest, daintiest pair of diagonal cutters I have and clipped away the relay's pins above the plastic 'floor' of the relay. This made unsoldering the pins and clearing the solder from the solder pads pretty easy.
This is a much-easier starting point than pulling this entire circuit board loose from the amplifier.
I chose a heavier-duty type relay meant to turn the AC power on and off in your TV. Naturally it will need jumper wires to connect to the circuit board. A strip of VHB adhesive foam will prevent it from wandering about.
Once it's in place this looks a bit "how-ya-doin" as Davy Jones might say, but it should be secure enough to last as long as anything else in the amplifier.
73
The circuit board holes where the relay will mount is empty in the front-most three circuit boards. The rear-most of the four has the keying transistor and relay found in the smaller models, but it serves only to switch 12 Volts DC when the mike is keyed. The output from this small relay splits off in two directions. First, to activate the coil in the large antenna relay, and second to supply base-bias current to the "R10" 25-ohm 5 Watt resistor on each of the four pc boards.
This amplifier had the heaviest-duty version of this small "R10"-size relay they sell, but still hesitated to close the circuit and trip the big relay. Removing the rear-most of the four circuit boards where this relay lives looked too much like an act of congress. So I took the sharpest, daintiest pair of diagonal cutters I have and clipped away the relay's pins above the plastic 'floor' of the relay. This made unsoldering the pins and clearing the solder from the solder pads pretty easy.
This is a much-easier starting point than pulling this entire circuit board loose from the amplifier.
I chose a heavier-duty type relay meant to turn the AC power on and off in your TV. Naturally it will need jumper wires to connect to the circuit board. A strip of VHB adhesive foam will prevent it from wandering about.
Once it's in place this looks a bit "how-ya-doin" as Davy Jones might say, but it should be secure enough to last as long as anything else in the amplifier.
73
