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Cant change or enter Final Idle Cur(430Mhz) in service menu


Ian Benjamin VE9HB
 

Hi everyone, first post in this group.
I am working on an IC7000, have the original problem pretty well fixed, but managed to create a problem for myself.
I went through the TX adjustment menu and did all the preceding Idle Current setups just fine.
The last item in the DRIVE/FINAL IDLING CURRENT,   "430MHz idle current"  was more of a problem.
The current value I found was a bit low, so I decided to set it to the correct value, even though the original problem was in the HF bands.
(I know, I know, if it ain't broke.......)
At first I couldn't get the current to drop to zero. Not sure how I managed to enter the 00 current setting, either by exiting the service menu, or by power cycling the radio. Now, I cant enter a non-zero bias current, or put back the original value.. Have tried all kinds of control, menu sequences, no luck.
Has anybody encountered or fixed this glitch?

BTW, original problem was low HF power on 20m band. Turned out the 20m band drew more current than the others, and tripped the overcurrent protection which was set too low. Drawing 20.5A @ 100W out.
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Thanks
Ian VE9HB


sv1dpp
 

Hi Ian,
the most likely cause is that the RD60HUF1 is in slow death situation or its damaged and you have to change it.
73 Spiros, SV1DPP


Ian Benjamin VE9HB
 

Hi Spiros
The loss of driver idle current occurred while I was going through the service menu setup. It was just over 2A, so I decided to bump it up to 2.5A. First you have to dial the current back to zero to measure the baseline current, and then dial it back up to add 2.5A to the baseline. At that point the process setup process hung, with the current intentionally dialed back to zero.
I hope its just a software glitch, and not failure of the driver. As far as I know, the UHF was working.
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Ian VE9HB


Ian Benjamin VE9HB
 

Sure enough, the UHF PA WAS BAD.  40 Ohms gate to ground. Replaced it, now around 1500 ohms gate to ground.
This can easily be seen during the Service Menu "403M Final Idle Cur". When adjusting the bias to max, the DC voltage at the gate wouldn't go much above 0.7VDC compared with 2-3V on the VHF PA gate. The low resistance at the gate was loading down the bias voltage circuit.
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Ian VE9HB