Tonite the power supply went to the great power supply resting place in the sky. Emailed JM on his disposition on this. As you might guess I expect it to be favorable.Does the buzzing get more intense when you modulate on AM? That's definitely a sign the RF is making it's way into the power supply. When you get into really big amps if there's enough getting in you can hear your voice plain as day. Not ideal.Although now that I think about it that really was more common with the older power supplies and not the switching ones. I've been using the MegaWatt for years without any RF issues on them even when testing some dirty CB amps.
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Boomer 400 RF making 50 amp switching power supply buzz.
- Thread starter 2315 Robert
- Start date
JM said they will handle it. Ship it well packaged. Where else in this world do you get that type of service. No where.
The problem is that you cannot measure peak current with that metering system. You are drawing MUCH more than that on voice peaks. If you are running 400 watts peak then that requires something in the order of 50-60 amps. If your box is class C it will run a bit less but if it is class AB it will require nearly 66 amps peak current for 400 watts peak output. Most people calculate current demand by dividing the power OUTPUT by the supply voltage and completely ignore efficiency which is typically 50% for a solid state class AB amp. A current meter will typically read about half to two thirds of that value unless it is capable of reading peak or inrush values. If your amp is indeed class AB then you were indeed exceeding the capabilities of the power supply on voice peaks. If it is class C then you were pretty much running the amp on the ragged edge of it's abilities. The Ameritron ALS-500m 500 watt mobile amp requires a supply of 80 amps for just an extra 100 watts. By extrapolation then 400 watts should require a peak of 64 amps.
Not surprised the supply failed nor that the response will be favorable.
That's one of the things I like about them as well. I own three of them and I will admit that I abuse them to some degree. I had a similar situation when I bought my second and JM knew I was using these supplies to run my test and repair bench. When one of the supplies started having a regulation problem I called and talked to JM and he sent a replacement power supply that same day. I sent the old supply back the day he gave me the tracking number of the new supply that was on it's it way. JM knows the value of a satisfied customer, I bought a 50 amp supply the next week just for good measure.
C
Thank you for the information. I need another 50 to make sure it is safe. I think I am talking apples and oranges here but, there is no way to combine my 36a and 50a together to handle loads of this amperage?
Thank you for the information. I need another 50 to make sure it is safe. I think I am talking apples and oranges here but, there is no way to combine my 36a and 50a together to handle loads of this amperage?
You should NEVER combine supplies with different current ratings. The current should be divided evenly between the two supplies and in this case you do NOT get a rating of 86 amps available to you. If you attempted to draw 80 amps the 36 amp supply would try and deliver 40 amps and would be exceeding it's rating. The 50 amp supply would be OK as it would be running below it's ratings..............well that is until the 36 amp supply failed and the 50 amp supply tries to supply all 80 amps. A pair of 50 amp supplies will provide a total of 100 amps since each supply is capable of supplying the same amount up to 50 amps each.
I don't think so. You can combine two of the fifties with no problem.
Could you use the 50 amp supply to run the amplifier and the 36 amp supply to run the radio?
Did I read that right your reflect is 25-30 watts! That is insane. Your input and output match has to be way off and look at combiner area as well.
If the Arco is not doing anything it either needs to be re soldered to the board or it is bad.
The buzzing sounds like stray rf getting into the supply. I have not heard a modern switcher buzz near it's limit way back int he day it was common but even a non switching depending on how well it was banded and potted the transformer would buzz near limit. This was especially true on home made units where they wrapped their own transformer etc....
Are the tins on everything? Are there plenty of screws on each set of tins? Have you tried a different amp or a different power supply?
Do not combine supplies unless the factory has rated the supplies for that use. If you do it any ways you need to have identical supplies and they each need to be tuned under load to identical levels. You need to have a load balancing/sharing circuit if they are not command master/slave designed. So you need some resistors and diodes at the very least and identical units. Load sensing on switchers is almost always on the negative lead when talking about DC with negative ground.
If the Arco is not doing anything it either needs to be re soldered to the board or it is bad.
The buzzing sounds like stray rf getting into the supply. I have not heard a modern switcher buzz near it's limit way back int he day it was common but even a non switching depending on how well it was banded and potted the transformer would buzz near limit. This was especially true on home made units where they wrapped their own transformer etc....
Are the tins on everything? Are there plenty of screws on each set of tins? Have you tried a different amp or a different power supply?
Do not combine supplies unless the factory has rated the supplies for that use. If you do it any ways you need to have identical supplies and they each need to be tuned under load to identical levels. You need to have a load balancing/sharing circuit if they are not command master/slave designed. So you need some resistors and diodes at the very least and identical units. Load sensing on switchers is almost always on the negative lead when talking about DC with negative ground.
Copy all of that. Yes on that reflect. Will have time to pull the board while I am waiting to be able to power it properly. Thank you.
Onelasttime, I see nothing out of the ordinary inside. Now running the Boomer(4 transistor 1446 HG) with a unmolested 980(3.6w deadkey swinging to 11w) into the dummy load. The no adjust statement I made on the var cap was wrong. Still showing 5 watts of reflect into the MFJ 828B meter. SWR 1.49. I have studied and searched long and hard, there is something I am missing. I understand that the contributors on here get tired of answering the same question. So the other findings on different three other 2 transistor amplifiers. SWR virtually the same and the reflect is the virtually the same. If a 2w deadkey should be at .56 reflect then a 3w dead key should be around 1w(these are all low drive and lowering the dead key really made no difference. I did find out that as soon as I did some short antenna tests that my antenna is bad(mad reflect). Swapped all coax to antenna same high reflect. Used an 8ft between radio and amplifier. Used 6ft between amplifier and meter. Used this on an all amplifiers still high reflect on dummy load and of coarse much worse on the antenna all still 20-30 reflect on all test subjects. Think I need to send the MFJ back for calibration as well. Are the cross needle meters any more accurate/reliable? Other interesting thing I noticed is that the amp draw with no modulation on 4 1446's is the same as 2 SRF's in my MC250 19amps. Any other feed back is greatly appreciated.(Since I specialize in reflect
) Thank you.
Shadetree Mechanic
Delaware Base Station 808
On the power supply would it help to use a big capacitor like used in car audio to help with the amperage peaks? On a side note about power supply emitting noise, I work on industrial electronics and the control power voltage is 24 volts. When one of the power supplies is near it's capacity, I have heard the transistors "scream" a high pitched noise. Not really loud but sometimes it coincides with the cycle of the machine depending on load.
Copy that STM. I have one just sitting in the garage from an old car audio set up. Do you remember what resistor to use when you initially charge it? Thank you this is a great idea.