The AM Forum

Just finished installing an IC-7100 HF/VHF/UHF mobile transceiver in the Tacoma and getting a feel for operating it, lots of menu and touchscreen stuff involved.

Hard copy manual is not clear re setting up for AM operation (essentially nothing).  Seems like it defaults to about an indicated 25-30% carrier level when set at 100% output in CW/SSB (a good feature), and I’ve adjusted the mix gain to just tickle the steady state carrier level on voice peaks.  Next step wil be to getting it going in  the shack so I listen to it and look at it on an o-scope.

Wondering if anyone on here has any experience with the 7100?

Chris AJ1G Stonington CT

Checked out AM performance with the 7100 in the shack both on the air and into a dummy load. With the factory settings, and the output power set to 100 percent, it’s putting out a nominal 35 watt carrier on AM, 100 watts in CW, so it looks like the set is programmed to cut back the AM carrier to about 1/3 of rated.  Didn’t sound too bad in the off air monitor or a local receiver. Scope trace looked ugly though. Nowhere near 100 percent moduation.  Tried raising mic gain above the default 50 percent, no improvement in scope wave form, audio on signal did not go up significantly.

Tried backing carrier level down to about 18 watts or so and started to see a more normal modulation trace on the scope.  Audio in the off air monitor and local receiver didn’t change much though.  Carrier level on external wattmeter shows downward shift with modulation at all output levels. Outpost power indication on the 7100 increased to 50-60 percent on voice peaks, must be measuring PEP.

Worked Timtron with it while mobile today on 3875!using factory settings, was told it sounded like  it had low modulation level.  Tim told me Mr. Mike W1RC tried to improve the AM performance of his 7100 without success.  Tim also mentioned a hack involving feeding a small DC voltage into the ALC signal of the Icom radios to improve AM performance. uses a battery and a pot to set the appropriate ALC level.  IIRC, WA1STH may have tried this on his 7300.  There is an ALC metering function and in AM it is steady at the maximum point of the scale with and without modulation.

Anybody else have any ideas on improving the AM performance of the 7100?
Other than that poor AM transmit modulation, set is very good.  Received SSB and  
AM audio when played through my Bose Soundink III aux input is excellent,  tinny using the tiny speaker in the control head.

I'll be watching this thread.  I have a IC7200 but I have not yet made an AM contact.  I'd love to get a modulation report.  I also just got a deal on a oscilloscope I'd like to use as a station monitor.

J,

Totaly unacceptabe.

Get on the air with watt  you got.............   I'm sure someone here will he happy to set up a sked with you.

The Official Fall Radio Season starts tomorrow. Please get on the air. Do it for the children.

KLC

What time, date, and frequency, and do you have an Amp?


Phil - AC0OB