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Galaxy DX-2547 suddenly virtually no output

OK Andy, here is what I have:

AM RF Power at Zero:
Unkeyed 5.28VDC
Keyed 5.04VDC

AM RF power at midpoint:
Unkeyed 7.03VDC
Keyed 6.75VDC

SSB RF power at 0:
Unkeyed 13.11VDC
Keyed 12.92VDC

SSB RF power at midpoint:
Unkeyed 13.11VDC
Keyed 12.93VDC
 
Wow, I posted results but they did not show so here goes again:

AM RF power set at 0:
Unkeyed 5.28VDC
Keyed 5.04VDC

AM RF power at midpoint:
Unkeyed 7.03VDC
Keyed 6.75VDC

SSB RF power set at 0:
Unkeyed 13.11VDC
Keyed 12.92VDC

SSB RF power at midpoint:
Unkeyed 13.11VDC
Keyed 12.93VDC
 
Ok, So LOW RF power on AM is set for 2.5 to 4 Watt setting and you're not getting there from the current Driver and Final Install...

Did you or someone you know, install MOSFET before?

This radio may have been a BIPOLAR board (set up and parts support for it)...
upload_2021-7-5_18-7-25.png
This Graphic shows MOSFET parts and DIODES installed
- but DRIVER and FINAL Numbers are SANDED off​

So you have to choose your poison - the more we know what has been done to the radio - the better off we ALL are for being there to help you get thru this.
 
Hi, so I got the radio about 6 months ago and I used it on and off several times with no problems. It came with 2pcs of an IRF520. Then the power dropped yesterday when I went to use it and luckily I had 2pcs of an IRF520N which I installed but did not really do much. So I guess I have mosfets, where do I take measurements so I can adjust the bias for each please? Thanks, I will try to take this a little further if you can help a little more. Adam
 

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Actually I tried a quick adjustment on the 2 trimmers but it did not make that much of a difference, maybe a 1/4 watt so I set the trimmers back to where they were so it must be something else. You mentioned diodes, do you know which ones I can check? Sorry, if this is taking too long and you want to stop I understand. Adam
 
IN the above example, you have LOW power, but voltages as far as your TP jumper and mirror board, are fine and appears to not have any issues with adjustments.

Only thing now is to see if you have Bias Voltages

So one of two things, do you have BIPOLAR in there or MOSFET.
upload_2021-7-5_18-25-7.png
The DIODES are different and ORIENTED
differently - 5.6V ZENER in MOSFET​

Review the above graphic...
 
Adamf said:
Hi, so I got the radio about 6 months ago and I used it on and off several times with no problems. It came with 2pcs of an IRF520. Then the power dropped yesterday when I went to use it and luckily I had 2pcs of an IRF520N which I installed but did not really do much. So I guess I have mosfets, where do I take measurements so I can adjust the bias for each please? Thanks, I will try to take this a little further if you can help a little more. Adam
Click to expand...

Don't worry you're ok, I am surfing thru all your posts and I never seen where you said I have a MOSFET board, just that you bought 520N's and put them in and now have no power.

Ok, looking at what I finally got out of this - YES you DO have a MOSFET board, so I don't have to guess where you're at ... thanks for the pic! (I was not sure if you were doing a CONVERSION or just put some FET's in where Bipolars were...)

Ok, Only other things that come to mind are...

The output Cap, the one that takes the RF from the Finals and puts it into the Output network and then out to the antenna.

That is this...

upload_2021-7-5_19-34-43.png
Got a 103 Disc cap?

​
 
Last edited:
Hi Andy, yes, I have .01uf disc. I have 50V for sure but would have to dig for higher voltage, is 50V OK to test with? Adam
 
Well, I did, but thinking he solved that when he swapped out to use the 520N's.

Else if it was a bad solder joint, the voltages would also have been skewed - so now - its' just related to output...

WHEW...
 

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