How do you setup a Flex 6XXX for AM mode

Dennis Daniel KM6DF

When I try to use the AM mode on my 6500 they say I am still on side band. I am using 1.9.7. i checked the scope and it looks like i am on AM. The operators manual dosen't say much on how to setup.
thanks 
Dennis KM6DF

Jim Gilliam

On AM the peak voltage amplitude of the audio is twice that of the resting carrier. When you modulate the peaks will give a peak power of 4 times the resting power. Therefore, you should not set your carrier level to more than 25 Watts or your signal will distort.

James Del Principe

Dennis, when you key the rig, you should see a line representing the carrier. Next, when you speak, you should see sidebands on both sides of the carrier and they will rise and fall with your voice. They will not appear to be four times the height of the carrier on screen. You will only see peak power of four times on a good peak reading watt meter. It is true the carrier will (should) be 25 watts which gives 100 watts peak but.... only on a major voice peak. I hope this is a help to you. 73, Jim

Alan, K2WS

Dennis, make certain that the AM Carrier slider is all the way to the right. Otherwise you will sound distorted on AM receivers employing "envelope detection" or diode detection. The RF Power slider can be set to 100 or any level above 0.

Ken - NM9P

Yes. On the 6000 series, the carrier level is automatically set to the proper level with the carrier level set to 100. Then set your mic gain so that it runs up to the yellow but never into the red on voice peakes. Do not use PROC or at least never more than NORM. But I recommend none at all. Set your TX bandwidth for 3000 Hz. (This is the audio bandwidth. Total TX bandwidth is twice that for AM. Adjust TX EQ for maximum clarity, remembering to readjust mic gain to keep in in line. Then have fun! The carrier level allows advanced users to reduce carrier level lower than the standard amount to provide a reduced carrier modulation which has greater than 100% positive cycle modulation while keeping the negative half of the cycle from going below zero. A little reduction, say to 95 or 90 can sometimes help some voices. But too much will be problematic for standard (non-synchronized) detectors.

Andrew VK5CV

If there is frequency selective fading (ie on the low bands) less modulation relative to the carrier may be better for conventional am detectors when the carrier fades.

WA2SQQ

Ken, I’ve commented on this in the past, but it might be worth mentioning again. I use my 6500 with my ACOM 1000 amp, on AM. Without any modulation I set the RF output from the 6500 to produce 250W out of the ACOM 1000. That allows it to safely run at 1KW peaks (250 x 4). Next, I reduce the AM carrier level to reduce the resting carrier out of the ACOM to 100W. On peaks it’s still hitting the 1KW peaks. This really reduces the ACOM’s operating temperature, and it has not caused any problems while being received by both SDR and legacy “boat anchors”. It sounds incredible!

Philip KA4KOE

Yes...one has to be careful with the resting carrier reduction. Too much and your audio quality goes out the window. If you are talking to other AMers and band conditions warrant it, go ahead and widen up you audio to at least 3.5 KC each side. Heck, my Johnson Valiant does 4.2 KC and sounds great. Of course, DON'T do this if you have band neighbors too close to you, eg. your audio sidebands extend into theirs.

Jim Miller

I have run am a few times on my 6300 and since I run a 2 kw amplifier I have to set the power controfl so that the carrier runs about 350 watts and set the mic gain not to get into the red.  I leave the carrier level at 100.  On my last qso with several am guys on 75 meters I got very good comments on my audio.  One ham said it sounded as good as the best plate modulated tube transmitter.  After the qso I looked the man up on qrz and discovered I was speaking to Bob Heil who should know good audio when he hears it. 

W3FJJ

I been operating a 6300 on AM for over a year, and never had bad report. I do run it into and amplifier with about 20 watts carrier. I set rf power all the way up, set the carrier level for 20 watts , I use an external scope, and adjust the mic level, so the audio negative peaks are close to base line. This gives me slightly more than 100 percent positive peak, but not too much to be distorted in diode detector. I have processor on in normal position, seems to give more dense audio, with no ill effects. Good luck.

James Del Principe

Hasn't been said yet that I can see but my AM group on 75 mornings always uses SAM...synchronous detection. Makes a big improvement during selective fading. BTW, we do not reduce carrier but I may try that...... and no processing.  Sounds great.   73, Jim

Kevin J. Darrah

I am unimpressed with the Flex 6400 on AM.... Correctly adjusted it yields about 50% modulation when the leveler is correctly adjusted to 0 DB with the Mic gain. 10 Watt Carrier modulating 20 watts PEP, confirmed with both an Oscilloscope and LP 100 watt meter. NOT what I would expect from any transmitter that was functioning correctly on AM. 

Bill -VA3WTB

James Del Principe

Kevin, I am on an AM group every morning on 75M and several of us use Flex 6000 series. We always get compliments from the others.   Much has been said here and it is good advice.  Are you using the hand held mic that comes with a Flex?   If so, put it in a drawer and get a good aftermarket mic. I am using a Yaesu MD 100 which is not the best on the market but works very well. Next, make sure the RF power out is set for max but slide the AM carrier level down just a bit. I use about 60 on the slider. it gives about 100+ watts (from the amplifier) out on "key down", carrier but with my amp, will peak at 1200 watts PEP.

Kevin J. Darrah

I use an Electro-Voice RE 27 Microphone, and an amplifier that uses a pair of 8877's. My amplifier cannot take anymore then 40 watts of drive for 1500 watts of output. The amplifier needs to be keyed with 10 watts and with peaks from the radio of 40 watts to be correctly modulated. As I stated, the radio with 10 watts will not modulate more then 20 watts peak when the leveler hits 0 DB. According to everyone, that's when distortion takes place. Obviously I have a malfunctioning 6000. 

Bill -VA3WTB

With proper settings your radio should have a carrier level of 25W allowing for 100w Drive.
If you can't get this then start a help desk so someone can help you.

Kevin J. Darrah

You can't use 100 watts with a pair of 8877's in the amplifier... Legal limit is 1500 watts and that would put me at around 5,000 watts peak. There was a specific reason for the 10 watts carrier/40 watts peak/100% modulation to give me 375 watts of carrier and 1500 watts PEP which I was achieving with a couple of other rigs. Again I appreciate the help, thank you and good night. 

James Del Principe

One other possibility is using a pad to reduce the output of the Flex or more accurately, to reduce the input to the amplifier.

Bill -VA3WTB

You don't have to operate at 100w,,that's silly. By adjusting the RF slider you can set the RF out to what ever you like. The Am carrier adjust the talk power. But 100w is there if your not using an amp.