The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

Rick I had forgotten about this until now, way back before you started helping me, back when this project began, a new pair of finals were installed, no change. Then a new driver was installed but the driver had the pins located on the wrong pads (installed wrong) Radio was quickly powered on then ...

Big Mike
All the cobra XL350 amplifiers I have seen use the same circuits as the messenger 350hd class Ab. The main difference is how the transistors are biased. The Cobra uses a regulated bias circuit and a variable pot to adjust the idle current. The messenger uses a fixed bias circuit.
CBTricks ...

Ramblingman, Thank you.
I went ahead and ordered the proper transistors. After i get them I will post my results.

Also, Rick thank you as well.
Rooster.

If this were my mobile, my radio & my 150 watt amp. I would put my watt meter in line then adjust my radio (carrier) until I saw 25-30% of the peak watts, 35-40 watts carrier and let it swing. Avg 80-110 watts.
Just my opinion, if it were my stuff.
Rooster

Ramblingman
Hey I went over the band switch and mode switch, both are functioning properly. I went over the entire PA section of the radio wicking up solder, scraping, reseting/soldering components. No output yet. I called the local parts store to inquire about a transistor for tr45.

The radio ...

Rick wrote:IC9 is OK then. Can you try your counter on the Base and Collector of TR45 and TR46 in AM mode, and let us know what frequency you have.

Do you have a RF probe or a scope?

27.170mhz does exist at collector tr-45

I noticed a voltage discrepancy at TR-51 Only getting 4.1v at collector on AM. But Normal voltage exist on SSB?

I do have a Tektronix 2211 scope with x10-x1 probe but I have absolutely no idea how to set it up.

I will see if my counter can-will measure those transistors. My counter has a probe ...

#1=22mv
2=8.0v
3=8.0v
4=22mv
5=8.0v
6=22mv
7=3.15v
8=3.14mv
9=22mvv
10=1.35v
11=1.55v
12=1.35v
13=1.54v
14=22mv
pins 14&10 has a resistor copper side 1k brn blk rd

TDA 6130-5 Germany I will measure the remainder now. I will post when finished.

Wanted 3-500 chimney. Can/will pay with PayPal.
Rooster

16.4900 @ R231
10.6970 @ R232
IC-9
Pin 2=8.02v
3=8.02v
4=22mv
6=22mv
7=3.14v
9=22mv
10=1.34v
11=1.55v
12=1.35v
Rick, I looked right over your last post. I have been at home all day snooping around this radio.

New findings
TX frequency set to 16.2675 using vr21 (TP3-r74) set ok
LSB/TX set to10.6975 using L28 (TP6-r102) set ok
USB/TX set to 10.6925 using L27 (TP6-r102) set ok

AM/TX needs to be 10.6950 (TP-R51) Test Point 51 does not present a valid frequency. Moved L26 with no change.

Driver current 70ma finals 97-99ma
A friend of mine has a device used to detect RF, he said no signal was present at IC9?
I do have a freq counter, I will connect it later to see what is at the test point/s.
I appreciate the help for certain but I'm almost at my rope's end. Had this radio ...

Rick, others, I now have the proper idle current at the driver and finals but still no output. Checked voltages at IC 9. Bear in mind I know very little but it seems to me that IC9 is not receiving a signal? Any further help would be greatly appreciated.

rockinredsrooster wrote:I will try adjusting the Bias for the listed transistors. I will post the findings shortly.
Rooster

Bias is showing 70ma, final Bias is showing 0ma current?

I will try adjusting the Bias for the listed transistors. I will post the findings shortly.
Rooster

Rick TP-9 AM=6.75v FM=6.75v SSB=13.8v
Driver sc2166 replaced with substitute sc1306
TR-44 AM(B)=.62v (C)=6.86v
TR-44 FM(B)=.67v (C)=6.8v
TR-44SSB(B)=.68v (C)=13.8v
Final sc2312
TR-43 AM(b)=.16v (C)=6.86v
TR-43 FM(B)=.16v (C)=6.8v
TR-43SSB(B)=.16 (C)=13.8v
Final sc2312
TR-56 AM(B)=.10v (C)=6.86v
TR ...

Rick, I will take those measurements later this morning to post here. I appreciate the help.
Rooster

Sharpshooter, you ever talk to a rooster in Cincinnati?

Good day, I have a galaxy 88 which does not transmit. So far I have replaced the finals and driver hoping to end this repair with an alignment.
Given that I'm an amature, here's what I have come up with so far.
The regulator tr-51 is ok, Tr-36 has the correct voltage, tr-41 correct as well.
With ...

RW023 wrote:whats the power out put off the amp , on am and ssb can some one help me out palomar tx5500 elite amp

I had one of these amps a long time ago, seems like I got an average of 400 watts. Milege can vary, driving radio, voltage, is the amp original etc.

I isolated the problem so my amp should be ok after a few changes. For inquiring minds, the tuning cap for the output was maybe 3/8's of an inch away from the chasis but worse yet one turn on the combiner was all but touching the chasis throwing my tuning way out. I shifted the board forward giving ...

Hey all, thanks for the membership, looking forward to this forum.

Anyhow, last night I built up an amplifier 4 2879's, class c. It seems to oscillating and i'm not sure why. I have put many of these amps together before but this time I used a very small case which caused me to do some minor stuff ...