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Thanks but??the ALC reading is?nearly nothing and I have played with the rf gain and power. ?

Well for some reason I have half scale reading ALC 2m?FM and 0 scale reading 70cm FM this is what makes it very confusing and know I am not looking at the swr meter.

Cheers Rick.

Rick,

Like I said before, watching ALC on FM doesn't tell you anything very useful. ?But it is useful to understand how ALC works in general, which will explain why you see what you do. ?

1. In the 7K, the ALC (Automatic Level Control) circuit controls bias to both the 3rd and 2nd IF amps early in the TX chain, which typically are designed with a lot of headroom and share the gain control. ?The pre-driver, driver and PA circuits operate at a fixed gain, although that gain varies across the bands significantly.
   
   
2. The ALC bias circuit is used to manually adjust TX power output and also by the APC (Automatic Power Control) to limit excessive forward power, excessive reflected power (SWR above 2.5:1 on HF), excessive PA collector current (due to thermal runaway or low voltage). ?It is also driven by the external ALC input on the ACC connector to help protect a linear amp.
   
   
3. All of the above affect the ALC meter display. ?When the ALC circuit reduces the IF bias voltage to decrease TX power output, the ALC meter level increases.
   
   
4. Reducing the manual TX PO power setting simply changes the reference voltage?used to compare the ALC circuit's forward power input, which comes from the directional coupler that senses the forward and reverse RF power to the antenna. When TX PO = 100%, the ALC comparison op amp has a higher voltage on the reference input. ?As long as the forward power level signal (FORL) is less than the reference input, the ALC bias level will remain at it's "idle" level. ?If FORL exceeds the TX PO reference level, then the op amp will decrease the ALC bias to the IF stages, which reduces drive to the PA stage until FORL is equal to the TX PO reference level again. ?
   
   If TX PO = 50%, the reference level to the ALC op amp will be a lower voltage, which will cause the ALC bias to be reduced until FORL signals that the requested TX PO is reached.
   
   
5. The ALC meter is not calibrated directly during service adjustments (except for some min and max limits for USB mode), so it will not necessarily be the same among a group of radios on all bands, different TX PO settings, varying supply voltages, etc.. ?This is especially noticeable in constant carrier modes like FM & CW. ?
   
   
6. What you observe on UHF, where the ALC = 0 with TX PO = 100% is common. ?The overall TX stage gain is lower on UHF, so the IF stages aren't being throttled back by ALC. ?But if you set TX PO=50%, the ALC meter will go up to mid-scale typically, indicating that the IF stage gain is being reduced to result in lower output power. ?You won't see this as clearly in SSB mode due to differences in how the ALC circuit works in that mode.
   
   
7. On VHF you reported that ALC was mid-scale. ?This is because the TX stages have more gain on that band, so the ALC bias is reduced to keep the forward power at the requested level.
   
   
8. There are many reasons why some indicators may not display consistent levels under various conditions or among different radios. ?Without understanding how the circuits work and how the service calibration procedure is done, it is difficult to appreciate why things are the way they are. ?My opinion is, if it needed to be calibrated, there is a procedure for it and the factory calibration is very consistent on the radios I've had an opportunity to measure with my analyzer. ?Pre-owned radios however, may have been tweaked...
   
   
9. Many users have the service manual and modify various settings, often without adequate test equipment, trying to increase RX sensitivity, increase TX power output at lower supply voltages, etc. ?I think it is very useful to read the service manual, understand the block diagrams, schematics, components and even the adjustment procedures. ?But going into the service menu and making changes without a thorough understanding of why it is calibrated the way it is, usually results in unfortunate, unintended side effects.
   
   Your radio seems to be OK, unless I missed some info along the way.
   
   
10. There are a lot of different opinions offered as a thread develops. ?It can be frustrating, but eventually the right questions get asked, more information is learned, the problem becomes clearer and an answer appears...

Thank you Steve that has given me a more of a understanding and direction to the my situation.

Cheers Rick.

Steve --

Thanks for the explanation!

. ? ? ? ? ? ? Charles / VA7CPC