RECENTLY AQUIRED AN ORIGINAL DAVE MADE M400 1X4. I HAVE A 13.8V 83 AMP POWER SUPPLY ON IT. JUST METERED IT AND ITS ONLY DOING ABOUT 500 OR SO WATTS. I AM WAITING FOR MY VARIABLE 13.8-15.5 VOLT 100 AMP TO COME IN. MY FIRST QUESTION IS, WILL I SEE GAINS IN WATTAGE WITH THE NEW POWER SUPPLY? 2ND QUESTION, IS THE AUDIO FEEDBACK NORMAL ON THE AMP AS WELL?
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DAVE MADE M400
- Thread starter 9 DOUBLE ZERO MINI GRASS
- Start date
Welcome to the forum.........
To your first question, probably if you turn the voltage higher than 13.8v, you will need to know the limit to how much voltage you can put into it, but 15.5v should be fine. If you want more power output get a bigger amp............
When you say "Audio feedback" do you mean:
* through other speakers (RFI) in the house?
* through your transmit signal (RFI) being picked up by the mic and sent out with your signal?
* through the speaker on the radio that does not have "talkback" also known as RFI?
* or is it something else?
Also, it's not polite to use all capital letters .... it's known as "screaming"
To your first question, probably if you turn the voltage higher than 13.8v, you will need to know the limit to how much voltage you can put into it, but 15.5v should be fine. If you want more power output get a bigger amp............
When you say "Audio feedback" do you mean:
* through other speakers (RFI) in the house?
* through your transmit signal (RFI) being picked up by the mic and sent out with your signal?
* through the speaker on the radio that does not have "talkback" also known as RFI?
* or is it something else?
Also, it's not polite to use all capital letters .... it's known as "screaming"
that amp should be doing way more. been loking online and the sweet spot is 14.5-15.5. i am making do with what i have. so i am not looking into getting a bigger amp. the feedback is coming out of the amp when i key down. sorry about the caps, i am at work and the programs that i am using require cap on.
The max amp draw for that amp is 110 amps, a power supply for max power out for the amp. To run it on SSB is an option.
The amp is a class C amp, meaning it's not made for SSB use unless it has the option.
The AM carrier keeps the amp keyed as long as you put enough power into it to keep it keyed while you talk.
If you are trying to use it on SSB then as you talk the relay in the amp will chatter as you talk, because there is no carrier on SSB, unless you have the SSB option.
If there is another problem you will have to explain it in more detail.
How long is the jumper cable between the radio and the amp? There have been problems that other people have had with amps that a longer jumper has made the difference.
The one thing you state is that the max power output is 500 watts or so, is that average or PEP? If it's average you would see a bigger swing on a PEP meter.
M400-M400
www.davemadeamps.com
The amp is a class C amp, meaning it's not made for SSB use unless it has the option.
The AM carrier keeps the amp keyed as long as you put enough power into it to keep it keyed while you talk.
If you are trying to use it on SSB then as you talk the relay in the amp will chatter as you talk, because there is no carrier on SSB, unless you have the SSB option.
If there is another problem you will have to explain it in more detail.
How long is the jumper cable between the radio and the amp? There have been problems that other people have had with amps that a longer jumper has made the difference.
The one thing you state is that the max power output is 500 watts or so, is that average or PEP? If it's average you would see a bigger swing on a PEP meter.
The max amp draw for that amp is 110 amps, a power supply for max power out for the amp. To run it on SSB is an option.
M400-M400
www.davemadeamps.com
The amp is a class C amp, meaning it's not made for SSB use unless it has the option.
The AM carrier keeps the amp keyed as long as you put enough power into it to keep it keyed while you talk.
If you are trying to use it on SSB then as you talk the relay in the amp will chatter as you talk, because there is no carrier on SSB, unless you have the SSB option.
If there is another problem you will have to explain it in more detail.
How long is the jumper cable between the radio and the amp? There have been problems that other people have had with amps that a longer jumper has made the difference.
The one thing you state is that the max power output is 500 watts or so, is that average or PEP? If it's average you would see a bigger swing
might just have to send it out for a tune up if anything. it is an original one so its getting up there in age. jurassic.
How much power average and PEP is the Cobra 29 putting out? The info on that amp says that it needs a max of 35 PEP watts while talking to drive the amp to the max output.
It also could and very well be that the 83 amp power supply isn't cutting it. You'll have to wait for the 100 amp supply to try it out.
Let us know what the bigger power supply does .......
It also could and very well be that the 83 amp power supply isn't cutting it. You'll have to wait for the 100 amp supply to try it out.
Let us know what the bigger power supply does .......
Before I forget...........
Since the new power supply is only 100 amps and the M-400 needs 110 amps, you'll have to run the radio on the smaller power supply and the amp on the new power supply.
Since the new power supply is only 100 amps and the M-400 needs 110 amps, you'll have to run the radio on the smaller power supply and the amp on the new power supply.
Are you measuring your power In pep or avg? What kinda meter you using
linearone,
Read post #5 where he wrote in the 2nd gray box using my name. It tells you what you want to know.
Read post #5 where he wrote in the 2nd gray box using my name. It tells you what you want to know.
I still don't understand what you mean by Audio Feedback. Are you talking about the talkback on your radio? Is it RF bleeding into speakers in your shack?
Right now I think your power supply is not able to keep up and I don't know if the 100 amp will do much better. The next question would be is your watt meter a true peak reading meter?
What is the dead key and swing from your Cobra 29? If your carrier is too hi that can cause backwards swing. You want the amp to dead key out between 100-150 watts max.
At this point we will assume your antenna, coax, jumpers, and power feed lines and ground are all good and correct. Curious to see what the 100 amp power supply can do.
Right now I think your power supply is not able to keep up and I don't know if the 100 amp will do much better. The next question would be is your watt meter a true peak reading meter?
What is the dead key and swing from your Cobra 29? If your carrier is too hi that can cause backwards swing. You want the amp to dead key out between 100-150 watts max.
At this point we will assume your antenna, coax, jumpers, and power feed lines and ground are all good and correct. Curious to see what the 100 amp power supply can do.
A Kenwood TS-50 ham radio made back when the 2SC2879 was still a new part used two of them to get 100 Watts peak. The Toshiba published data for this part claimed 120 Watts peak per transistor. Two of them held down to 50 Watts each are pretty rugged, and will mostly shrug if the antenna SWR gets too high.
Four of them delivering 500 Watts is pretty well on the money for what Toshiba claims for it.
Then again, folks who fancy what they call "competition" performance will obtain this by boosting the power supply voltage above 13.8 Volts.
There is a relationship between power-supply voltage and amplifier output called a 'square law'. This means that if you were to double the power supply to 27 Volts you would see four times the power, or 2000 Watts.
In real life, this wouldn't be for very long. Certainly not long enough to snap a picture of the wattmeter. Probably not long enough for the meter needle to travel upwards.
But if we only increase the power supply voltage by half-again more than 13.8, this is around 20 Volts. The square law says that we'll see about double the wattage we did at the lower power supply voltage.
The Toshiba transistor was made for so long and in such quantities that the quality grew really high, and the abuse that it could take was equally high.
Running it from 20 Volts counts as abuse for me, but your mileage may vary. Not so different from putting a nitrous bottle on your daily driver. But the life of that engine will no doubt be reduced, compared to operating it at stock rated power.
Newer parts from other suppliers are all you can buy since Toshiba quit making that part for good. None of them are as stout as the original Toshiba. How much 'competition' abuse they can take is an open question. Mostly you find out when they go "snap!".
It's worth considering that what the receiver at the far end of your conversation will hear if you double your power.
S-meters vary a lot from one radio to the next, but doubling your power will show between one-half and one whole S-unit on the meter. To me, that doesn't seem worth blowing up an amplifier with the nitrous treatment. People get excited when they see a wattmeter increase by half-again, say from 500 to 750 Watts. Looks like a lot on your wattmeter, but it's still kinda far from double.
YMMV.
73
Four of them delivering 500 Watts is pretty well on the money for what Toshiba claims for it.
Then again, folks who fancy what they call "competition" performance will obtain this by boosting the power supply voltage above 13.8 Volts.
There is a relationship between power-supply voltage and amplifier output called a 'square law'. This means that if you were to double the power supply to 27 Volts you would see four times the power, or 2000 Watts.
In real life, this wouldn't be for very long. Certainly not long enough to snap a picture of the wattmeter. Probably not long enough for the meter needle to travel upwards.
But if we only increase the power supply voltage by half-again more than 13.8, this is around 20 Volts. The square law says that we'll see about double the wattage we did at the lower power supply voltage.
The Toshiba transistor was made for so long and in such quantities that the quality grew really high, and the abuse that it could take was equally high.
Running it from 20 Volts counts as abuse for me, but your mileage may vary. Not so different from putting a nitrous bottle on your daily driver. But the life of that engine will no doubt be reduced, compared to operating it at stock rated power.
Newer parts from other suppliers are all you can buy since Toshiba quit making that part for good. None of them are as stout as the original Toshiba. How much 'competition' abuse they can take is an open question. Mostly you find out when they go "snap!".
It's worth considering that what the receiver at the far end of your conversation will hear if you double your power.
S-meters vary a lot from one radio to the next, but doubling your power will show between one-half and one whole S-unit on the meter. To me, that doesn't seem worth blowing up an amplifier with the nitrous treatment. People get excited when they see a wattmeter increase by half-again, say from 500 to 750 Watts. Looks like a lot on your wattmeter, but it's still kinda far from double.
YMMV.
73
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