How and where do i check the filters
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Andrew,? Are you able to correctly adjust all of the Drive/Final Idling Currents?? For adjusting TX power output, using the correct mic audio level and frequency as specified in procedure is important.? What are you using to measure the idle currents?? What are the actual measured currents in the 4-4 Transmitter Adjustments, steps 2-7?
Are you able to verify the TX voltages by stage as given in :??/g/ic7000/files/7K%20TX%20RF%20Levels%203.pdf? ?? Make sure your radio settings match those in the first paragraphs.? It is important to have a ground spring clip on the probe's ground barrel (instead of a normal ground wire clip) to eliminate noise coupling and get accurate readings. Since all bands appear to have a problem, it is unlikely to be a problem with high or low pass filters or their switching diodes & relays.? But you can verify them by seeing that the input signal level is okay per the above document, then checking the signal level on the output of the filter.? The switching diodes and their control voltages are more likely to be a problem than the actual filter circuit. Steve, W3AHL |
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None of the voltages you measured are close to what I normally see.? The first set of levels from the IF should vary with frequency, but yours don't.? They look like just noise levels.? What instrument are you using to measure them?? Do you see a valid RF signal waveform with a peak that moves when you change the frequency dial a little?? Are you using a scope probe with a 4" ground lead?? That would account for the constant RF noise level.? Unfortunately I am at my home in Washington state, but all of my test equipment is at my home in New Mexico, so I can't send you a picture of the correct probe grounding method.
When you say you cannot adjust the output via the service menu, what do you see when you try to adjust the driver and final idle currents.? That is a purely static DC bias adjustment that only measures the DC supply current coming into the radio using an accurate DC shunt and voltmeter or a clamp-on DC current meter.? Even if you cannot adjust anything, it would perhaps be useful to know what currents you measure in steps 2-7 anyway.? That will indicated if the bias control circuits and FET's are alive. It's hard to troubleshoot remotely, so providing a little more detail of what you are doing would be helpful.? I have no idea what your repair experience is and what equipment you are using.? Sometimes just misunderstanding one step in the adjustment procedures can make all the difference.... |
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Here's the manual for the probe that shipped with that model:??
On page 4 is the parts list.? You should remove parts 2 & 3, then attach part # 5 (ground spring) to the ground barrel of the probe.? Then take measurements of the IF output, placing the ground spring on the nearest ground trace on the PCB.? This will eliminate the background noise picked up by the wire ground clip. I don't understand your comment:? "i can see each ptest the voltage jumps!" Are you able to measure the current on the DC power cable while doing the idle current adjustment steps?? I can't provide any troubleshooting help without basic information.... Steve, W3AHL |
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Thanks for sharing your situation.? I looked at your info on QRZ and you have a nice station.? The IC-7000 isn't easy to troubleshoot!
Your latest J101 IF measurements looks like the unit isn't going into transmit mode.? Does the TX LED on the control panel come on when you key it in CW mode? Since your unit receives okay, the IF circuits seem to be working.? Most of it is the same for RX & TX modes, except the pre-amps are bypassed in TX. It's difficult to tell you where to look next.? If the TX LED is on when you keyed the unit to measure the signal levels, then the problem is probably on the MAIN board, which is harder to troubleshoot and repair.? Is there a ham in a local radio club perhaps that has experience working on Icom radios??? The 7000 is old enough that it probably isn't worth the cost of sending to a repair shop for this type of problem.? I know you have invested a lot of time and effort into it so far and? wish I could be of more help.... |
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Maybe there is an issue with how the scope is set up?? The probe's slide switch should be on 10X and the Channel Menu for Probe should be 10X also.? Maybe the trigger level is set too low or the horizontal sweep rate is too fast.? When you press and hold the key for a few seconds, do you see the voltage stay at the level show on your previous post?
Parts on the MAIN board are very sensitive to static discharge and can be damaged by a zap (or by a probe tip shorting two leads together).? You should wear an ESD wrist band that is grounded through a 100K ohm resistor and work on an unfiinished wooden or carboard surface (a grounded conductive ESD mat is better) also.?? Steve, W3AHL |
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Andrew,? You don't specify which voltages appear on which leads of Q101.? I don't have my 7K and test equipment with me at my current location, but you should see the collector be about 13.8 VDC in RX mode and about 0.7 VDC in TX mode.? The emitter is tied to ground, the base is controlled by T8 (Transmit 8 VDC control signal) through a resistor divider, so it should be about 0 VDC in RX and something less than 8 VDC in TX.
This RF Switch is used to mute the RX signals coming from the PA board via J101 to the RX IF circuits during TX mode.? It doesn't affect the TX output functions. Steve, W3AHL |
Steve W3AHL