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Ca346
| | Posted on Sunday, November 02, 2003 - 6:42 pm: | 
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In getting ready to move the second radio and amp and power supply to the shop/garage, (COPPER IMAX2000 on the way)I have been "testing" the set-up by running it all on one power supply (Pyramid46) which is a 40amp supply.
In the past, I always used two power supplies. One for the radio, and one for the amp (Galaxy350).
HERE'S MY QUESTION: I notice the voltage dropping to 11 to 11 1/2 volts when I use the combination. OHM's law says E=IR, where E=Volts, I=Amps, and R=Resistance or Ohms. So if my voltage is dropping, can I decrease resistance somehow, to get it back up to 12 Volts? OR, .... TWEAK the power supply to give more Voltage? |
Mr_Rf
| | Posted on Sunday, November 02, 2003 - 9:07 pm: |
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Assuming the meters you are reading are built into the supply it really sounds like the supply may be overloaded with both the radio and amp. Also assuming the supply is set to deliver between 13 to 14 volts a drop below 12 volts on a regulated supply would indicate overload or regulator circuit trouble.
Now, if the measurements are by an external meter then increasing the diameter of the wire between the supply and equipemnt would help out...and make sure RF isn't getting into the meter and causing erronious readings before tearing into the setup. To do this wrap as many turns of the meter leads as possible around the metal part of a screwdriver and take the measurements again. If you see more than a few tenths change then the meter is being fooled by the RF. |
Znut
| | Posted on Sunday, November 02, 2003 - 10:23 pm: |
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The voltage should not vary like that at the terminals on the P.S.
Were you reading this from a VOM in series or parrallel or from a built in meter? |
Simon
| | Posted on Monday, November 03, 2003 - 9:08 am: |
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Voltage will drop if the power supply is trying to supply too much current - same as a partially flat battery terminal voltage drops on demand.
I agree with Mr RF as far as the external Volt meter and larger wires BUT there maybe a nother explanation too.
If relying on internal meters check with an external one as its just possible that RF is getting into the Supplies metering circuit and causing a false reading. Possible but not too likely but I have known it to happen on one or two occasions.
Check and see |
Ca346
| | Posted on Monday, November 03, 2003 - 11:28 am: |
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I tend to forget that I cannot rely on the meters that are in the power supply to accuratley reflect what is happening in the circuit. I have been told before about the inaccurate meters in the Pyramid power supplies (another past thread). [I don't listen well...] I was not reading external meters; Only the meters in the Pyramid-46KX. The only other power supply I have is a MFJ-4035, which does not have enough maximum amperage on it's own to test the set-up at maximum power.
Max power is also "dimming the meter lights", which I know is an obvious indicator that you are all correct. I will run less power on the amp (which I do normally anyway) until I can afford ($$$) another small power supply to run the radio and amp seperatly.
I will eventually also check the regulator circuit, but need someone to do that for me, so will put it off for now.
I will have to rely on the new COPPER IMAX 2000; Propagation; and an excellent radio (President HR2510 (Lincoln)) to get out there sufficiently! |
Mr_Rf
| | Posted on Monday, November 03, 2003 - 8:27 pm: |
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If it is RF getting back into the power supply then it not only could be affecting the meter but instead the regulator circuit. Two things to try is to add a .001uf and .01uf ceramic disc capacitors across the DC output connections of the power supply. You can also try wrapping several turns of the DC wires going to the supply terminals around a ferrite core along with the capacitors. Ferrite cores used to be available from Radio Shack, and maybe Copper too??? This combination would usually solve 99% of the RF issues with regulator and meter circuits. If it is RF and still have problems after these methods then that would indicate a poor design and wiring internal the supply acting like and antenna picking RF out of the air and detecting it.
Good Luck |
Ca346
| | Posted on Monday, November 03, 2003 - 10:53 pm: |
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RF/John:
I will check for RF. It is currently sitting extremely close to the radio and amp.... Amazing how some of the most simple things are forgotten after awhile.... My whole permanent radio shack is extremely well grounded. BUT... the set-up is very temporary for the power supply, radio and amp that I will move into the shop/garage. I am embarassed to say that NONE of the 3 items are currently grounded. I keep changing some things, and forgot to run any ground to the amp! I put a ground wire on it as soon as I got it, but it is curled up in a coil behind it...
When I get it moved, it will all be seperated and grounded sufficiently. Also, I know that COPPER sells the RF chokes from another thread, where I recommended the same solution for something else.
THEN, I'll look at the cap,s you suggest. Thanks,
CA346/CEF197 |
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