| Author |
Message |
    
fdirsh
| | Posted on Saturday, October 05, 2002 - 7:20 am: | 
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I have a 6 pill base box with 2879's in it. The transformer is not acquidate to handle this amp. The reason I say this is because when I key it down the fan slows and it should do more that 600 watts when driven.
It has a small transformer made in mexico in it. Does anyone have any suggestions or know what wouls be an efficient transformer to put in this amp.
I can change it myself if I had a specification as to what to replace it with.
Thanks for any help!!!!!!!! |
Taz
| | Posted on Saturday, October 05, 2002 - 2:49 pm: |
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did you build it or but it.
If you bought it from an amp manufacture then you are using to much deadkey.
If you made it then put in a bigger one. |
bruce
| | Posted on Saturday, October 05, 2002 - 3:39 pm: |
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taz if it has a number stamped on it maby we can find out what the transformer is? |
Taz
| | Posted on Saturday, October 05, 2002 - 5:35 pm: |
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I was speaking of the amp bruce
But yes, we can do that. |
Czar
| | Posted on Saturday, October 05, 2002 - 6:58 pm: |
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Hey TAZ, are you ever on the air or just the computer???? Do you have ssb capabilities ??? If so go to 27.555usb and give me a call. |
Taz
| | Posted on Saturday, October 05, 2002 - 7:32 pm: |
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haha,
yes I have ssb capabillities, but since my ssb radio isnt here then im sol for ssb.
Where are you again czar? |
Czar
| | Posted on Saturday, October 05, 2002 - 8:17 pm: |
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Hey TAZ,I am in north phoenix around I-51 and greenway rd. |
Taz
| | Posted on Saturday, October 05, 2002 - 9:12 pm: |
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Well, that wouldnt be an easy contact since your on the other side of a mountain would it?
Im at 101 and I-10 |
Czar
| | Posted on Saturday, October 05, 2002 - 10:20 pm: |
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Taz ,it is an easy contact, I have a 60 foot towerand 1.5 kilowatts,I hit avondale with a s-7to s-9 all the time!!!!! |
fdirsh
| | Posted on Saturday, October 05, 2002 - 10:26 pm: |
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The transformer number is 430-7001-4 then EIA 6- 9517 then Class 180 H1 then MEXICO. It also has two big caps they are 15 volts and 120000uf.
TAZ it is a high drive and I am only keying 90 watts swinging 150 into it for a final d.k. of 300 swinging 1kw. The fan slows and I know a 6 pill with 2879's should do 1.2 to 1.5 kw. I just want it to have full power even if I only run it at 1/2 of cap. |
Taz
| | Posted on Saturday, October 05, 2002 - 11:02 pm: |
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actually, no.
What you are getting out of it is what you are supposed to.
The amp just needs all the power it can get and it steals it from the fan.
2879's are rated at 100 watts.
6 2879's even at 125 watts is 750 watts.
How many volts into the transistors are you running? |
Monk
| | Posted on Sunday, October 06, 2002 - 1:35 am: |
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The reason the fans slow on base transistor amps is that the power supply is not regulated. All the ones I have seen have a basic power supply consisting of a transformer, a bridge, and a cap. No voltage regulator or pass transistors.
Monk |
Taz
| | Posted on Sunday, October 06, 2002 - 3:16 pm: |
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I have noticed even on regulated ones if the amp is driven to hard the fan will slow down. |
Tech671
| | Posted on Sunday, October 06, 2002 - 7:31 pm: |
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It is normal on most unregulated DC base amps to have the fan slow. Since you already have the cover off, check the voltage to the board of the amp without keying, then when it is keyed. It's likely at 18.5v unloaded and 15v or so loaded. If your loaded voltage is dropping below 14v then it could be underpowered by the transformer, or it could be reflection, or it could be your wall receptacle isn't providing enough current to it. |
fdirsh
| | Posted on Monday, October 07, 2002 - 10:30 am: |
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Thanks tech671 you have the most sinceable resolution. |
Fdirsh
| | Posted on Monday, October 07, 2002 - 8:25 pm: |
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Ok.
I checked the voltage and it is 20.8 and when I key it down it drops to 13.8.
Is this good or bad. I would think bad. I think it should at least be 16.5 volts.
Any suggestions??? |
Tech671
| | Posted on Monday, October 07, 2002 - 11:02 pm: |
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Could be weak rectifiers, could be weak txfmr or underpowered. |
Bigbob
| | Posted on Tuesday, October 08, 2002 - 8:59 pm: |
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WHERE can I buy a really big transformer like 200 amps @20volts out,220 volts in? |
Taz
| | Posted on Tuesday, October 08, 2002 - 11:09 pm: |
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ummm, i dont know. thats big |
2600
| | Posted on Wednesday, October 09, 2002 - 12:52 am: |
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http://www.pwdahl.com/
Best source of custom transformers on the planet, that I know about.
Also, be aware that a "brushless" DC fan has a solid-state driver circuit in the center hub. RF will ROUTINELY 'bleed' this driver circuit, as if it were a $9.00 Walgreens' telephone. The effect is to slow (or sometimes stall) the blade. I have seen plenty of them slow down in proportion to the carrier knob on the radio, even though the supply voltage was holding steady on a meter. When they stall, the coils inside start to heat up in a hurry. Folks who chuckle at the blade rocking back and forth in place change their mood about the time smoke starts to pour from the fan motor.
Filtering the red and black leads as close to the motor body as possible will stop or minimize this. Disc capacitors across the power leads, and choke coils/ferrite beads in line with the wires are showing up BUILT INTO a lot of mobile amps these days. Seems the consumers don't like fan smoke.
Finding out which brands of fan do this dumb trick the worst is trial-and error, just like finding a cheap phone you won't bleed into.
73
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