Output volume higher at less power?

[ForestRunner98]

I was wondering why output volume is higher at lower radio power? When increase RF power the output volume doesn’t seem as high. Example at 2w volume is greater than at 5w. Is it the limiter kicking in? Radio is a President McKinley.

I am using another radio as a receive with headphones on. It does the same with and without a power mic. Do I have the AMC and ALC too high? I lowered the RF power but it doesn’t seem to have enough swing for SSB. On AM it’s fine..swings like it should!!

Just curious. Thank you all!!!

 

[AudioShockwav]

AMC controls modulation in AM mode only.
ALC controls the level of SSB only.
If AM is good, just bump the ALC for SSB.
Without test equipment I would adjust ALC untill you see no increase in peak power on SSB then back off just a bit.
Some radios struggle to have enough headroom to modulate the carrier x 4 on AM peaks but you are saying AM is good.

73
Jeff

 

[ForestRunner98]

ALC and AMC are adjusted to max and backed off a tad. What I don’t understand why when the radios RF power is increased the output volume (heard on another radio) is lower. Both AM and SSB. It’s not a lot of difference but I can tell.

So when on AM I have the RF power at 2w(15w swing) and 5w(12w swing) on SSB. Running with a KL203 not that it makes a difference. Just for info.

 

[nomadradio]

Ah, okay. I think what you're asking is why the radio's mike gain seems to increase as you reduce the carrier power.

This is because the loudness on the other end is determined by your modulation percentage, not your wattmeter reading.

Turn down the carrier, and the audio power feeding into the final stage remains the same. The same audio power now becomes a higher percentage of the total signal.

Listening to a AM radio on another receiver in the room, turning down the carrier will change the APPARENT mike gain, even though the wattmeter reading was reduced. By the time the carrier gets down below a half Watt, it makes a straight mike sound like a power mike.

As the carrier level falls, your audio POWER stayed the same, making the modulation percentage rise as the carrier power falls.

47 years ago, I set up a CB shop's service department from scratch. I decided that I should be able to hear what's coming out of a customer's transmitter. I hooked up the "relative power" jack on our dummy load to a small PA amplifier. This served us well, and allowed the customer to hear "before and after" audio from his radio.

Until the first time we put a carrier control on a CB. Just happened to have a radio on the same channel. Turned down the carrier, and the volume from my dummy-load monitor speaker fell off along with the wattmeter reading.

But the volume from the receiver across the room INCREASED! Got my attention right away. My boss was a bit puzzled at first, but he had been an electronics instructor in the Marine Corps and gave it some thought. I can't remember whether his idiot light came on before mine, but we figured it out there on the spot.

AM modulation 'loudness' is a percentage of the carrier power, The higher the percentage, the louder it gets.

And ever since that day, we use a radio on the same channel to monitor a customer's transmit audio. The PA amplifier went into the closet.

73

 

[ForestRunner98]

Ah, okay. I think what you're asking is why the radio's mike gain seems to increase as you reduce the carrier power.

This is because the loudness on the other end is determined by your modulation percentage, not your wattmeter reading.

Turn down the carrier, and the audio power feeding into the final stage remains the same. The same audio power now becomes a higher percentage of the total signal.

Listening to a AM radio on another receiver in the room, turning down the carrier will change the APPARENT mike gain, even though the wattmeter reading was reduced. By the time the carrier gets down below a half Watt, it makes a straight mike sound like a power mike.

As the carrier level falls, your audio POWER stayed the same, making the modulation percentage rise as the carrier power falls.

47 years ago, I set up a CB shop's service department from scratch. I decided that I should be able to hear what's coming out of a customer's transmitter. I hooked up the "relative power" jack on our dummy load to a small PA amplifier. This served us well, and allowed the customer to hear "before and after" audio from his radio.

Until the first time we put a carrier control on a CB. Just happened to have a radio on the same channel. Turned down the carrier, and the volume from my dummy-load monitor speaker fell off along with the wattmeter reading.

But the volume from the receiver across the room INCREASED! Got my attention right away. My boss was a bit puzzled at first, but he had been an electronics instructor in the Marine Corps and gave it some thought. I can't remember whether his idiot light came on before mine, but we figured it out there on the spot.

AM modulation 'loudness' is a percentage of the carrier power, The higher the percentage, the louder it gets.

And ever since that day, we use a radio on the same channel to monitor a customer's transmit audio. The PA amplifier went into the closet.

73

Yes yes yes..that’s it!!! Ah ok. I had to read it about 5 times to make it sink in. LOL

That’s interesting! I never noticed before. I was fiddling around with a new mic(power) and it caught my ear. Started thinking the mic gain is too high and AMC/ALC is too also too high. I switched back to the stock President mic and same results! So I thought maybe I messed up something in thr radio.

I searched around the interweb and could not find anything. Hope this thread helps another radio person!!

Thank you and audioshock for posting!!!