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DEI Transistors
- Thread starter Drifter
- Start date
You seem to really know a whole lot, but you're only taking the path we've already taken. There's truth behind what you're being told.
I'm not entirely sure. My ammeter is extremely sensitive and when I'm modulating it bounces all over. BUT, it seems to be topping at about 45 amps. I DO know that the draw dropped quite a bit since I removed the fuses and upgraded the power wires. If I can locate another ammeter I will replace mine.
Here, you can read all about it.
https://www.worldwidedx.com/threads/texas-star-with-dei-2879s.258848/
Your a new member here, if you take a little time to read the forum, you will find that a lot of the guys here have been doing this radio stuff for a while.
Mike, from Texas Star has a account here , he could chime in any time he wants, in fact I am the one that sent him a e mail and suggested he join years back.
There is a very good user base here that have years of radio and amp experience, many work on and build equipment .
Welcome to the forum.
73
Jeff
And update on my DEI equipped DX-500V:
When I first pulled it pout the of the box it was putting out 450 to 475 Watts of PEP @ 62 Amp draw. The power supply was idling at 14.2 volts and pulling down to about 13.8 volts under modulation.
I ripped out the power wires and removed the fuses, ran 4 lengths of #10 stranded wire ( one got and one grnd from each board( terminated with a 175 Amp Anderson Power pole. Upgraded the power supply output to 6ga wire and 80A fuse. End results are as follows:
Amp now holds steady at 650 watts of PEP @ 42 Amp draw. Power idles at 14.2 volts and pulls down to 14.0 volts under modulation. Less draw, less voltage drop with heavier wires less fuses. All tests before and after the power wire upgrade were done using the same power supplies, same voltages and a steady 30 watt pep drive from my Yaesu FT-990 on SSB.
When I first pulled it pout the of the box it was putting out 450 to 475 Watts of PEP @ 62 Amp draw. The power supply was idling at 14.2 volts and pulling down to about 13.8 volts under modulation.
I ripped out the power wires and removed the fuses, ran 4 lengths of #10 stranded wire ( one got and one grnd from each board( terminated with a 175 Amp Anderson Power pole. Upgraded the power supply output to 6ga wire and 80A fuse. End results are as follows:
Amp now holds steady at 650 watts of PEP @ 42 Amp draw. Power idles at 14.2 volts and pulls down to 14.0 volts under modulation. Less draw, less voltage drop with heavier wires less fuses. All tests before and after the power wire upgrade were done using the same power supplies, same voltages and a steady 30 watt pep drive from my Yaesu FT-990 on SSB.
Sounds like after your upgrades the box is really kickin the cat and walkin the dog.
I did the same upgrade to an older DX-350 for a buddy after he saw mine. The same results were achieved. I don't his numbers in front of me, but his went from averaging about 275 0r 285 watts pep, to about 380 with a 20 watt drive. His unit has two 2879s and I'm not sure what the drive should be so we kept it as 20 pep. My conclusion is that Texas Star needs to dump the 12ga wire and crappy 30A fuses and start supplying some current to these things. The two pill versions need an 8ga power wire, and the 4 pills need 6ga or at least twin 10 ga ( 4 wires total) for power.
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Something is not adding up here. Using heavier wire with an 80 amp fuse will lower the overall resistance this load presents to the DC source. Assuming this was the only variable to increase power output, it must also increase the current draw proportionally. The lower resistance and voltage drop in the DC wiring, should always cause a slight increase in amperage, not a decrease.
No. Higher resistance, lower voltage = higher current draw. I now have less voltage drop, so higher voltage = lower amp draw. Ohms law.
That doesn't compute in my mind.
Higher voltage divided by lower resistance results in more current.
Hence more power output.
"Ohm's Law"
I = V divided by R
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That doesn't compute in my mind.
Higher voltage divided by lower resistance results in more current.
Hence more power output.
"Ohm's Law"
I = V divided by R
I think if you're talking in terms of "normal" usage this is correct. However, being that wires have an ampacity rating kinda messes the works. These amplifiers are actually starved because the power wires are much too light. I'm not saying the current is actually being used by the amp, but rather being lost in the wire and/or converted to heat. Once the amplifier is fed properly, the current is no longer lost in the journey.
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