Hey all,
I typically work USB and LSB but I found a couple nets that use AM. I have the output power settings limited by band to 50w so I don't over drive my amp (it has a 50w input). I have found however, that when transmitting the output power recorded on my HF-Auto antenna tuner is far lower than what I typically see on USB/LSB. Is this normal on AM or am I doing something wrong? Could anyone suggest some "getting started" settings for AM with the SUNSDR2DX? I know audio varies by user, but some general set-up stuff that helps on AM would be helpful. Then I can tweak from there.

I know when I had my TS-890s the settings between USB/LSB were vastly different in terms of drive power, mic gain, etc.

Thanks in advance for any advice.
73
Rich
W1SPS

W1SPS пишет:
Yes, that would be correct

Rember AM is carrier based so your setting of 50 watts means roughly at a 1:4 ratio which most AM tends to do is
12.5 watts carrier and if you achieve 100% full Positive AM modulation (yes there are negative peaks in AM) then you would get slightly less at the 50W setting

also keep in mind that 50% isn't linear on the drive setting, 50 % doesn't mean 50 watts same as with the tune function those are not a 1:1 locked ratio

And as far as I recall V3 isn't really a 25% ration of carrier power- seems to me it was a bit less so your 12.5 watts carrier maybe close to say 5-8 watts of carrier resulting in a possible 32 watts if you 100% positive modulation is archived.

I see.. I think. So, on AM I could run the full drive output as what hits the amp would be somewhere in the order of 1/4 of the 100 watt output (so 20-25w)? So is it better to have a dedicated AM amplifier that runs on less drive?
Thanks
Rich

W1SPS пишет:
NO Don't do that!

Slowly bring up the drive on a good voice peak like a AHH etc. and watch were that hits on power out peak (Without the AMP ON) and make your adjustment for peak by watching the levels, Then I would set it, so it is below that threshold, so you don't over drive or drive the AMP on a loud noise or some harsh tone / sibilance

Also keep in mind that AM is 100 percent duty cycle there is always output in the form of a carrier. So, watch that with Temps and your amp as well

I see. Ok, I will try that. Thanks a lot.

Rich

With your power limited at 50W you can only run about 10-12W carrier power

Carrier power * 4 is PEP roughly.

AM will heat a rig up fast. I run AM fairly often and use an amplifier to keep things in balance. I typically run about 2-3W carrier power from the Sun to drive the amp to about 200-250W carrier power.

I was getting 188-200w or so as displayed on my HF-Auto tuner. I will check my setting to make sure I am in that envelope. I did get good audio and signal reports. This is going from the SUNSDR2DX to my Gemini DX1200 amp to my HF-Auto.

Thanks a lot for the info.
Rich
W1SPS

When you key up and don’t speak….audio muted, that is your carrier level.

The Sun does a pretty decent job so you should get close to 100% modulation and that should be about 4x the carrier power read on a PEP meter.

That Gemini should be able to do around 200W carrier output. The main thing is to see what the power level is where the temp will climb but level off or slow in rise by a lot and the cooling keeps up with it. As long as you watch your temps you should be ok. Some amps handle it better than others.