Bricked my 959 final version

[Chainsaw660]

I did a mod on my 959 that I found on defpom. It will no longer transmit. Put everything back to stock still no tx I followed these steps to the letter. Help plz.


RF Output Increase Modification

This modification will allow the DX959 & DX949 to exhibit the RF output and swing of the Galaxy DX-series 10-meter radios. The board was always capable of this type of output; it was simply choked off by the design engineers in order to meet FCC 11-meter specifications.

The first thing you need to do is turn up VR14 which is the AM high power variable. If you?ve already done the modulation improvements, you should be able to dead key about 8-10 watts and swing around 15 watts. 18 watts is probably the best you?ll get (using a peak-reading Bird wattmeter). Now, perform the following modifications:

1. Remove C218 (3pf) and discard.
2. Change C216 (470pf) to a 1000pf (100V mylar-type)
3. Remove C210 (470pf) and discard.
4. Remove C199 (560pf) and reinstall it in the C210 spot.

Adjust your dead key to around 5 watts. I was able to achieve average peak swing readings of around 35 watts. Depending on the audio input (voice or whistle), I was able to whistle myself to readings of over 40 watts peak! There was a slight decrease in modulation and it seemed as though I was really pushing it. I found that I was able to regain the modulation level by lowering the dead key (using the RF Power control on the radio face) to around 2.5 watts. This netted peak swing readings of just around 28 watts! More than enough given the fact that the modulation was over 95% and crystal clear! This is just about the same performance that I got from my Galaxy DX66V after performing the 1N4001 diode heavy swing modification. Like I alluded to earlier, this new radio has "the stuff." You just have to work slightly harder to get at

 

[DoctorAudio]

One of these will fix it so it never needs fixing again. Most reliable tool on any tech bench.

Joking of course.. Can you hear it transmitting on a radio sitting next to it on the bench?

 

[groundwire]

that modification sounds pointless. 28w pep? every 959 i ever had did 25w-30w pep without any modification at all. you should have just left it alone.

 

[techradioman]

Why do people hack up and destroy equipment for NO reason ?

 

[brandon7861]

I did a mod on my 959 that I found on defpom. It will no longer transmit. Put everything back to stock still no tx I followed these steps to the letter. Help plz.


RF Output Increase Modification

This modification will allow the DX959 & DX949 to exhibit the RF output and swing of the Galaxy DX-series 10-meter radios. The board was always capable of this type of output; it was simply choked off by the design engineers in order to meet FCC 11-meter specifications.

The first thing you need to do is turn up VR14 which is the AM high power variable. If you?ve already done the modulation improvements, you should be able to dead key about 8-10 watts and swing around 15 watts. 18 watts is probably the best you?ll get (using a peak-reading Bird wattmeter). Now, perform the following modifications:

1. Remove C218 (3pf) and discard.
2. Change C216 (470pf) to a 1000pf (100V mylar-type)
3. Remove C210 (470pf) and discard.
4. Remove C199 (560pf) and reinstall it in the C210 spot.

Adjust your dead key to around 5 watts. I was able to achieve average peak swing readings of around 35 watts. Depending on the audio input (voice or whistle), I was able to whistle myself to readings of over 40 watts peak! There was a slight decrease in modulation and it seemed as though I was really pushing it. I found that I was able to regain the modulation level by lowering the dead key (using the RF Power control on the radio face) to around 2.5 watts. This netted peak swing readings of just around 28 watts! More than enough given the fact that the modulation was over 95% and crystal clear! This is just about the same performance that I got from my Galaxy DX66V after performing the 1N4001 diode heavy swing modification. Like I alluded to earlier, this new radio has "the stuff." You just have to work slightly harder to get at

Power transistors are most stable near their saturation point where gain is lowest. As the drive is lowered (like SSB quiet periods or reducing your dead key to nothing), the collector current decreases, but not as fast as the base current. The gain is going up. If it goes up enough, it can cause self-oscillation. The capacitor provides negative feedback to compensate for that increase in gain and its value is specifically chosen for that transistor type and circuit enviroment.

You didn't just change it, you removed all negative feedback and also raised the gain by messing with the drive level.

 

[brandon7861]

That means you are looking for bad transistors. It went into self-oscillation, thats for sure. But at what frequency? Id be checking everything from that transistor all the way through the finals (as they were working their hardest into a serious mismatch), have a look at your AM regulator, and check for anything else burnt on the board before trying to power it again (and do so with a current-limited supply).

 

[Greg T]

Time to buy a new radio and weld the cover shut.

 

[Crawdad7]

One of these will fix it so it never needs fixing again. Most reliable tool on any tech bench.
View attachment 63105
Joking of course.. Can you hear it transmitting on a radio sitting next to it on the bench?

The first RCI2990 (now deceased) met a LARGE Limestone rock multiple time in the Alley. Rocks work 2.

 

[brandon7861]

Spare yourself the life-long guilt that comes with smashing any radio and just drop it in my mailbox. It wasn't the radio's fault, it deserves a second chance. I'll reimburse you for the shipping when it arrives.

 

[AxlMyk]

Why do people hack up and destroy equipment for NO reason ?

For our amusement.

 

[Enterprise312ok]

You cant blame a guy for trying to get just a little more power.

 

[DoctorAudio]

Yeah, we were a little harsh on the new guy...
Chainsaw660, maybe you could do some preliminary tests like check the voltages on the AM regulator/modulator with the radio keyed and also see if you can set the idle bias on the driver and final.

 

[Enterprise312ok]

The first RCI2990 (now deceased) met a LARGE Limestone rock multiple time in the Alley. Rocks work 2.

D104s That have the chicken choker and lazy bar make me feel that way.(when the switch is bent and filed to nothing and your trying to make it work)

 

[Handy Andy]

Now I'm only going by what you posted...so by your word...


The above items are the ones discussed in the mod section you quoted...

Problem here is, did you VERIFY that the parts pulled, their values even matched?

Why do I ask?

Ever solve for X?

Read this thread...

Galaxy DX-2547 low SSB output, help?

Hi all, so a while ago I posted about low output on my DX-2547 and was not able to get too far so I retested the radio today and find that on AM my output is about 3 watts dead key and swings to 17 watts or so which is fine but on SSB I can only get up to about 10 watts with full modulation, I...

www.worldwidedx.com

And this one...

ept069611a single mosfet Galaxy DX 2547

Ok all, Got another on my desk. It's a single final mosfet version Galaxy DX 2547 with the ept069611a board. The issue is "no am transmit". Everything else works great. Sideband does around 42 watts on both LSB and USB. Just no AM transmit at all, no carrier or audio on AM. Nothing gets...

www.worldwidedx.com

Why? Better realize that when you REMOVE parts, you might need to keep the support parts in, or at least PUT a support part in to keep that section stable and working. OR even check to see if that sections support parts are even installed?

Did you bother to look and see if there were parts omitted on the board, that show up on the schematic - then wonder why?

This looks to be one of those Enigmas...

I'm trying to be kind here...the effort of the mod was to get more swing - but one thing no one mentioned even in the mod page, is the TYPE of RF meter - it's brand - or setting up the whole mess in the first place to attain those measurements - was ever discussed.

Too many variables - and if you had done your homework, you can avoid this hassle and embarrassment from the enigmas' like this, can become - from ever showing up again.

 

[CrazyCouillon]

Your problem is solved in 5 easy steps:
1) Put everything into a baggie.
2) Put Baggie inside rig and close panels.
3) Send your rig to an experienced Tech with instructions to reset to standard.
4) Fork out the necessary $$ when Tech says radio can be collected.
5) Go home and enjoy your CB.