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Interpreting transmitter adjustment instructions

 

Page 18 (marked 4-3) of the service manual explains adjustment of the final idle current.? It mentions connecting an ammeter that monitors the power supply current during the test and power meters to both antenna jacks.? Then it has this text:
?
Rotate [DIAL] to set adjustment value to
1 A value from the driving current of "00"
value. Then push [F-4 (SET )].
?
But there is no instructions for connecting an ammeter to the driver stage to measure or adjust its current.? Does "driving current" here actually mean the power supply current?? If yes, does this mean that one is supposed to record the power supply current when the adjustment value is at zero, then increase the adjustment setting until the power supply current is 1.0A more than it was at the zero setting?
?
Cheers,
Halden VE7UTS
 

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Hi the way to look at this is this:

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  1. Connect an 1-5 amp meter (DVM) in series with the rig, or use a power supply that shows current digitally.
  2. Set all the bias controls to zero
  3. Switch on and put into to TX (SSB)
  4. Note the current the rig draws.
  5. You can then adjust the driver ideal current for an additional 1A
  6. You can then adjust the driver VHF Final current for an additional 2A
  7. You can then adjust the driver UHF Final current for an additional 2.5A

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When you switch form HF to VHF to UHF, the bias current falls to zero on the non-use band

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MOSFET unlike bi-polar are nearer to class A (AB2) than Class AB1, or B (which is just conducting)

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KR

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Andrew G8UUG

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From: [email protected] <[email protected]> On Behalf Of HF via groups.io
Sent: 11 April 2025 06:17
To: [email protected]
Subject: [ic7000] Interpreting transmitter adjustment instructions

?

Page 18 (marked 4-3) of the service manual explains adjustment of the final idle current.? It mentions connecting an ammeter that monitors the power supply current during the test and power meters to both antenna jacks.? Then it has this text:

?

Rotate [DIAL] to set adjustment value to
1 A value from the driving current of "00"
value. Then push [F-4 (SET )].

?

But there is no instructions for connecting an ammeter to the driver stage to measure or adjust its current.? Does "driving current" here actually mean the power supply current?? If yes, does this mean that one is supposed to record the power supply current when the adjustment value is at zero, then increase the adjustment setting until the power supply current is 1.0A more than it was at the zero setting?

?

Cheers,

Halden VE7UTS
 

Thanks for the confirmation, Andrew.
In the first setting, "TX Driver Idle", the radio drew 1.57A at setting 00, which gradually increased with higher settings until it went from 1.80 A to 2.67A between setting 72 and 73.? Turning the knob CCW brought it down slowly to 2.55 at setting 60.? But when I re-enter the test at setting 60, or if I turn it down to 00 and back up to 60 again, the radio draws 1.78 A.? Is this how it's supposed to work?? If not, what component of the driver circuit is likely to have failed, causing this hysteresis?
The next two settings seemed to work okay.? The setpoints were in the vicinity of the original setpoints.
The third one, "Final Idle (144M)", drew 9.9A with a setting of 00, falling to 8.7A after about 10 seconds.? Turning the knob was able to get it up to 9.7A, but I thought there might be a malfunction, so I turned it back down to 00.? The 4th one, "Final Idle (430M)", drew 1.57 to 1.60 A regardless of the setting.? I left it at 00 too.
I didn't connect the microphone exactly as the service manual says.? Instead, I used the regular microphone in a quiet room.? When I pressed the microphone's PTT switch; the radio went into TX mode and stayed in TX mode until I pressed F4 (SET) and/or the up arrow (F1) to go back to the top of the test menu.
I'm working on these adjustments because the radio gives low output on all HF and 50M bands.? The amount of low output varies; I started out with 29W on 40m and when I went back to it after checking all the other bands, it was down to 14W.? Most bands' power output was in the 5-10W range.? I haven't checked power output on 2m or 0.7m; I don't have a good wattmeter for VHF and UHF.
Does the high current on 2m and low current on 0.7m mean the final transistors for those bands have failed?
Cheers,
Halden VE7UTS
 

Hi you have a ribbon cable fault which is putting DC on the gate of the VHF transistor, this needs to be fixed first.

KR

Andrew

Get
On 12 Apr 2025, at 07:16, "HF via " <yahoo.com@groups.io target=_blank>[email protected]> wrote:

Thanks for the confirmation, Andrew.
In the first setting, "TX Driver Idle", the radio drew 1.57A at setting 00, which gradually increased with higher settings until it went from 1.80 A to 2.67A between setting 72 and 73.? Turning the knob CCW brought it down slowly to 2.55 at setting 60.? But when I re-enter the test at setting 60, or if I turn it down to 00 and back up to 60 again, the radio draws 1.78 A.? Is this how it's supposed to work?? If not, what component of the driver circuit is likely to have failed, causing this hysteresis?
The next two settings seemed to work okay.? The setpoints were in the vicinity of the original setpoints.
The third one, "Final Idle (144M)", drew 9.9A with a setting of 00, falling to 8.7A after about 10 seconds.? Turning the knob was able to get it up to 9.7A, but I thought there might be a malfunction, so I turned it back down to 00.? The 4th one, "Final Idle (430M)", drew 1.57 to 1.60 A regardless of the setting.? I left it at 00 too.
I didn't connect the microphone exactly as the service manual says.? Instead, I used the regular microphone in a quiet room.? When I pressed the microphone's PTT switch; the radio went into TX mode and stayed in TX mode until I pressed F4 (SET) and/or the up arrow (F1) to go back to the top of the test menu.
I'm working on these adjustments because the radio gives low output on all HF and 50M bands.? The amount of low output varies; I started out with 29W on 40m and when I went back to it after checking all the other bands, it was down to 14W.? Most bands' power output was in the 5-10W range.? I haven't checked power output on 2m or 0.7m; I don't have a good wattmeter for VHF and UHF.
Does the high current on 2m and low current on 0.7m mean the final transistors for those bands have failed?
Cheers,
Halden VE7UTS

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