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Old 02-15-2016, 9:13 AM
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Question Suggestions for am gear?

I currently can run AM on my Icom 7600----I am concerned about it's duty cycle. So I am looking for suggestions on a transceiver which is designed for AM use only.
I generally run all the HF bands.
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Old 02-15-2016, 9:15 AM
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A CB... LOL
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Old 02-15-2016, 9:17 AM
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2nd that.....
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Old 02-15-2016, 10:30 AM
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Quote:
Originally Posted by WB3DYE View Post
I currently can run AM on my Icom 7600----I am concerned about it's duty cycle. So I am looking for suggestions on a transceiver which is designed for AM use only.
AM is a 100% duty cycle mode, but why are you worried it? According to the manual for the 7600, the output power (continuously adjustable) is:

SSB/CW/RTTY/FM : Less than 2 to 100 W

AM : Less than 1 to 30 W

When your running AM, the power is limited to a maximum of 30 watts. That's 30 percent of the peak power in SSB. That should be well within the limitations of the power amplifier and heat sinks.

I have a IC-735 and it has a similar reduction in output power for the AM mode. I wouldn't hesitate using it on AM.

Of course, you could go get a old DX-40 (75W) or DX-60 (90W). But they may take a little work to get them operating again. I have a DX-40, but haven't used it in a long time.

Martin - K7MEM
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Old 02-15-2016, 10:44 AM
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A 100% AM modulated signal is 6dB or 75% more power than the unmodulated AM carrier level, so a 100w radio would be limited to 25w with no modulation to allow for 100w peak when fully modulated. Any modern amateur HF radio will transmit for a long time at these power levels in AM mode without any problems.

Some modern HF rigs are not really AM on transmit, they use USB then add some carrier in the 25-30w range to emulated AM modulation. This works OK and you can tell who's using this type by receiving them in SSB. If you hear them find in both sidebands its probably a real AM transmitter, if you only hear them in USB its one of "those" rigs.

On most rigs I've found you usually need to adjust mic levels, processing and EQ a little to maximize the transmit sound over settings specifically for SSB.
prcguy
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Old 02-15-2016, 12:36 PM
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Quote:
Originally Posted by WB3DYE View Post
I currently can run AM on my Icom 7600----I am concerned about it's duty cycle. So I am looking for suggestions on a transceiver which is designed for AM use only.
I generally run all the HF bands.
There aren't really any modern rigs designed for AM only. There just is not a big enough market to warrant such a development. That does not really matter much though, as many modern rigs have quite decent AM operation.

I use my FTdx-5000 and my Flex-5000a for AM on the HF bands quite a bit, my FT-2000 a little also. Both of the 5000's get good reports, and I often listen to my signal on remote receivers. All three of them did require custom configuration to get the most out of AM operation, but that was not really difficult, just had to work around the right menus and settings. I imagine many decent modern radios could be set up similar.

As prcguy indicated, duty cycle is probably not an issue. A radio rated at continuous 100% duty cycle and 100 Watts will do a 25 Watt carrier, 100% modulation, signal all day long. And how long do you key down for? Yes, I know AM roundtables can get long winded, but I have a hard time keeping the key mashed for 3 or 4 straight minutes, not much longer than some SSTV transmissions. And then you are unkeyed for however long it takes to get back around to you.

I can say I have never had an issue with any of the rigs I currently use.

T!
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Old 02-15-2016, 1:33 PM
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You could add some more cooling capacity to your current radio....
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Old 02-15-2016, 2:28 PM
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Default am transmitter

E.F.Johnson Viking,or Ranger.
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Old 02-15-2016, 2:52 PM
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As it has been pointed out, most decent AM radios are old restored tube radios. The popularity of SSB brought an end to dedicated amateur AM rigs.

Best bet would be to listen in or even join in on an AM roundtable and find out what they're using or what they recommend.. AM Frequencies

FWIW, I've got an IC-7600. I use it with an Ameritron ALS-600 amplifier (the rare time I mess with AM). 10 Watts AM into the Linear gives me 100 Watts out. In this case both the radio and the amp are running well under their maximum power levels.
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Old 02-15-2016, 2:58 PM
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Quote:
Originally Posted by WB3DYE View Post
I currently can run AM on my Icom 7600----I am concerned about it's duty cycle. So I am looking for suggestions on a transceiver which is designed for AM use only.
I generally run all the HF bands.
Probably not what you are looking for when you san "I generally run all the HF bands.", but I've got a co-worker who's running an old AM broadcast transmitter on the 160 meter band. I think it's running about 500 watts. Obviously no duty cycle limitations.
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Old 02-17-2016, 9:14 PM
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Smile AM HF radio

Though this quite old, I have still have an Icom 720 that did a smashing job for years and years on 160 metres AM. I used it a lot in the Pacific as a KX6 on that band -- I would turn it down to ~50 watts- and, well, 'worked the world' (on AM with a short, loaded vertical antenna.) Maybe you can find one out there?
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Old 02-22-2016, 9:22 AM
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An EICO 720 was my first rig, and they do work well. But mine was a bit dirty with harmonics. When I got my General, I upgraded to a used Heath.

If you can find an old Heath Apache, or similar, they have great broadcast quality audio. Also they are built like a tank, and weigh close to 70-80 pounds. Check out the reviews on eHam.
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