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Kenwood TS-440S signal meter problem
- Thread starter Pelltom
- Start date
Not sure if it's normal for the 440 but my 430 does the same thing and I would imagine that there is a logical reason but I cannot answer that.
I'm not sure if I'm understanding the question correctly but, this is one explanation for what you're seeing.
An AM signal's power changes almost constantly to some extent. That's why you see the 'S' meter wiggle. Am FM signal has a constant power level, what changes with modulation is the frequency, which stays centered on one particular frequency. That FM signal on an 'S' meter will show a constant power level.
Make sense?
- 'Doc
An AM signal's power changes almost constantly to some extent. That's why you see the 'S' meter wiggle. Am FM signal has a constant power level, what changes with modulation is the frequency, which stays centered on one particular frequency. That FM signal on an 'S' meter will show a constant power level.
Make sense?
- 'Doc
And just for grins...
You can 'make out' FM when in the AM receive mode. Have to do the tuning just right, and it'll never be very clear/plain, but it can be done. Doesn't work the other way around though. At least I couldn't make it work. Too easy to just punch a button to FM. Oh well.
- 'Doc
Another just for grins.
The '430 and '440 were similar, but not just a 'new box'. Big differences in how things were accomplished. Some aspects were better with the '440, some weren't. So what else is new?
You can 'make out' FM when in the AM receive mode. Have to do the tuning just right, and it'll never be very clear/plain, but it can be done. Doesn't work the other way around though. At least I couldn't make it work. Too easy to just punch a button to FM. Oh well.
- 'Doc
Another just for grins.
The '430 and '440 were similar, but not just a 'new box'. Big differences in how things were accomplished. Some aspects were better with the '440, some weren't. So what else is new?
Your rig is probably working normally.
Hammy rig's S meters are non-linear on FM due to the limiter stage in the I.F. amp. That stage is there to remove the AM response in an FM system. There is a lot more gain because of this. The S meter responds to AGC voltage. That voltage will be non-linear on FM due to the limiter.
If you wish to have relatively more accurate S meter readings for experiments use the rig on AM receive to take the reading even if it is an FM signal.
All this stuff is well covered in older ARRL handbooks. FM techniques are a lot different than other phone modes.
The 440 and 430 don't share much in terms of layout. The 440 has an additional 455 khz I.F. stage.
Hammy rig's S meters are non-linear on FM due to the limiter stage in the I.F. amp. That stage is there to remove the AM response in an FM system. There is a lot more gain because of this. The S meter responds to AGC voltage. That voltage will be non-linear on FM due to the limiter.
If you wish to have relatively more accurate S meter readings for experiments use the rig on AM receive to take the reading even if it is an FM signal.
All this stuff is well covered in older ARRL handbooks. FM techniques are a lot different than other phone modes.
The 440 and 430 don't share much in terms of layout. The 440 has an additional 455 khz I.F. stage.
hiiiiiiii
This Modification allows for the Kenwood TS-440s transceiver to have the data audio on PIN 11 of the 13 pin DIN connector ACC JACK 2. Later models may or maynot have a correction for this, but my PK-232, or for that fact NONE of my TNC's would drive the audio to the PIN 11 of ACC JACK 2. Encountering this problem, and having another H.F. transceiver I have been using the REMOTE connector, and using an audio input to the AFSK IN RCA type connector. This would allow me to use the same cable with my TS-180s also. Anyway this modification moves the wire's from the AFSK IN to the ACC 2 connector. This should only take about 20 to 30 minutes to preform this change, and most of the time is used up with the removal, and replacement of the THREE covers of the transceivers cabinet.
This Modification allows for the Kenwood TS-440s transceiver to have the data audio on PIN 11 of the 13 pin DIN connector ACC JACK 2. Later models may or maynot have a correction for this, but my PK-232, or for that fact NONE of my TNC's would drive the audio to the PIN 11 of ACC JACK 2. Encountering this problem, and having another H.F. transceiver I have been using the REMOTE connector, and using an audio input to the AFSK IN RCA type connector. This would allow me to use the same cable with my TS-180s also. Anyway this modification moves the wire's from the AFSK IN to the ACC 2 connector. This should only take about 20 to 30 minutes to preform this change, and most of the time is used up with the removal, and replacement of the THREE covers of the transceivers cabinet.
HiDef has the real answer. The AGC is completely different on FM than on AM. Try this sometime. Tune in a carrier using AM mode and then switch on your preamp and note the difference in signal strength. Now switch to FM mode and while looking at the same carrier switch the preamp on. Notice that in FM mode it appears that the preamp has much more gain than in AM mode? Of course it does not and is mode independent but it just shows the difference in meter readings from AM to FM. Often newbies to 2m are extremely impressed with their new antennas and think they have massive F/B ratios or gains because of the vast difference in signal on the front versus the backside of the antenna based on signal strength readings. What they fail to recognise is that often a signal can be S-4 or 5 on FM and still not be what is truely called full quieting whereas the same signal in AM mode is. It's all due to the differences in the way each mode handles the AGC.