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eHam Forums / Mods And Repairs / Alinco DX-70T low output on some bands
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on: August 26, 2008, 02:46:09 PM
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I've got a similar problem with the 160 meter lo-pass filter being ON all the time.
In mine however, the L-0 control line never gets above +9 V when it should be at least +12 V to have the relays off.
What exact diode did you find open on the LPF board?
73' Charlie k3ich
k3ich (at) arrl (dot) net
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eHam Forums / Mods And Repairs / ALINCO DX-70 LOW output
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on: August 25, 2008, 06:38:35 PM
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Which diodes are you referring to when you say they're the cause of the low output/filter problems with the Alinco DX-70?
I have one in which the 160 meter lowpass filter is always engaged regardless of which other filter is also switched on for different bands. The control line BB0/BB4 into the filter board's ribbon connector from the serial to parallel chips (uPD6345's), never goes above 8 Volts on the 160 meter (L0) line. All the rest, L1 - L5 go to 12 V. This keeps the upside down PNP transistors which control the IN/OUT relays on that filter turned on. I can force the line to 12 V so that all the other bands will work fine, but then 160 never switches on.
There are two double diode packs which combine BB lines L0 & L3. L3 by the way works fine. There are also diodes across the relays and probably others. Which ones cause the problem?
Thanks, charlie k3ICH
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eHam Forums / Mods And Repairs / ALINCO DX-70 LOW output
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on: August 25, 2008, 06:38:34 PM
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Which diodes are you referring to when you say they're the cause of the low output/filter problems with the Alinco DX-70?
I have one in which the 160 meter lowpass filter is always engaged regardless of which other filter is also switched on for different bands. The control line BB0/BB4 into the filter board's ribbon connector from the serial to parallel chips (uPD6345's), never goes above 8 Volts on the 160 meter (L0) line. All the rest, L1 - L5 go to 12 V. This keeps the upside down PNP transistors which control the IN/OUT relays on that filter turned on. I can force the line to 12 V so that all the other bands will work fine, but then 160 never switches on.
There are two double diode packs which combine BB lines L0 & L3. L3 by the way works fine. There are also diodes across the relays and probably others. Which ones cause the problem?
Thanks, charlie k3ICH
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