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PE1OOY > DSP 04.09.98 01:51l 32 Lines 1576 Bytes #-9686 (0) @ WW
BID : 23180_PI8MBQ
Read: DK5RAS GUEST
Subj: ICOM 706MKII power DSP problem mod!
Path: DB0AAB<DB0ZKA<DB0ABH<DB0SRS<DB0SIF<DB0HSK<PI8DRS<PI8ZWL<PI8APD<PI8GCB<
PI8MBQ
Sent: 980903/2224Z @:PI8MBQ.#NH2.NLD.EU #:23180 [Haarlem, JO22HJ] FBB7.00g
From: PE1OOY@PI8MBQ.#NH2.NLD.EU
To : DSP@WW
Hai dr OM, hereby a real good mod for power (voltage problem) with SSB audio
and use of DSP unit.
Here is to bypass that problem:
The problem with SSB is that below 11.8 volt regulator SMD IC2 stops
regulation.
Another IC706 DSP mod
The modification to restore the 5V supply to the DSP at supply voltages below 12 VDC by shunting the already modified R18 with another resistor results in extra heat generated next to the DSP unit. By removing the original TA7805 altogether from the circu
- lift the leg next to the shielding can of the TA7805, if necessary cut it (the chip itself stays on the board but does nothing anymore)
- mount the 7805 upside down on the fan on the other side of the radio, below the DSP unit
- bypass input and output pins to the ground pin with 0.1uF ceramic capacitors
- solder two wires to the in- and output pins and lead them to the other side of the radio
- remove R18 and solder the wire to the input pin into the hole to the 12V supply
- solder the wire to the output to the pad where the leg of the TA7805 was connected to
This completes the modification. Be sure to check that the speaker screws don't touch the 7805.
This should solve the problems, of course, perform this mod at your own risk.
73 de Tjerk PE1HKMThe ICOM IC-706MKII I own is modified this way, and work perfectly. The earia
around dsp unit is cool now!
I run the radio in my car, without running engine, with no problems.
73! De Kees PE1OOY At: PE1OOY@PI8MBQ.#NH2.NLD.eu
VY 73 FROM PE1OOY/G7TWO, Kees Hoofddorp,NL
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