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

speedracer6g

Thanks, I will give that a try and see what happens.

MIke

speedracer6g

I need a unit to replace L13. It is marked LB361. Does anyone have one they can get rid of or know where i can find it.

thanks,

Mike

speedracer6g

AMP PIC.JPG I replaced the part with a resistor already as seen in the pic i attached. R19 is beside the keying relay. when i key up but on med and high power it stays keyed after you unkey the transmitter. I dont think this is the main cause of this but i would like to get this part back to OEM. T...

speedracer6g

I have a palomar elite 450hd amp that had a resistor burnt to badly to identify. I cant find any schematic on this thing. Does anyone know what the value of R19 in this amp.

thanks,

Mike

speedracer6g

I found the problem. There was a oscillation showing up on the output of ic7 after a minuit or two. Replaced ic7 njm4558. Works great. thanks for all your help. It was hard to find since it didnt affect the am side.

MIKE

speedracer6g

It appears to be an audio oscillation coming from the mic amp IC7. It is high enough frequency that it is inaudible. things are starting to make sense here finally. I just have to find out what is causing the audio problem now. aarrrgg.

MIKE

speedracer6g

I replaced C149, C144, C146, C145, R172, R174, R169, Q34, D57, AND R171. I checked pin one and there seems to be an oscillation the shows up when things go sour. I checked and the oscillation is present at R171. I was going to trace that to see if i could isolate where the noise is coming from. Any ...

speedracer6g

thanks for the tips. I will recheck my supply voltages just to make sure. I think i did already but I will recheck to make sure. thanks again for your time and support.

MIKE

speedracer6g

I checked the output of the balanced modulator IC6 pin 7 and it shows no carrier only audio when things are working properly. However when the radio quits working right i notice that carrier is showing up on pin 7 as well. I have tried to replace ic6 with no results.

MIKE

speedracer6g

I tried replacing IC6 and it still did the same thing. It is almost like a resistor is opening up or there is a bad cap somewhere in the balanced modulator circuit. I talked to galaxy tech and they had no answers. I will keep digging around ic6 to see what components are involved.

thanks,

Mike

speedracer6g

Galaxy 98vhp motorola 2100b service monitor, scope, frequency counter, bird 43p meter, dosy tc3001-p meter, 75 amp power suply, simpson vom meter, digital multimeter, ect. Am works fine, altough on at one time on low power it had no deadkey unless you turned up the rf power. that problem i have not ...

speedracer6g

i have on of those here in my shop and that threw me off a little bit. I think it has to do with dual watch option. if you turn it off you should be able to use the radio normally. Let me know how you make out.

MIKE

speedracer6g

Found a service bulliten from cobra. had to install a cap from ground to c607.

http://www.cbtricks.com/radios/cobra/15 ... _10043.pdf

this seems to have fixed the problem.

speedracer6g

Cobra 150 gtl The radio works fine on low power. On high power it gets some distortion like the amc is punching holes in the audio. It only seems to do it during when you first talk like the amc is not working right on the high power side. any ideas? I am working on it here but i figured i would see...

speedracer6g

I just did this mod in my shop here today. I realy didnt have much need until they quit making the mini mag. I came up with the same results basically. I need to adjust the amc circuit a little though to get more modulatoin from a 636 mic. I have to play around with the amc and mic amp a little. I d...

speedracer6g

On a Cobra 25 it goes on the center leg of tr16. Sorry about that.

MIKE

speedracer6g

Anyone have a schematic for the new Cobra 25ltd with the TDA2003 audio chip. I did a search and could not find one.

thanks,

MikeD

speedracer6g

It should run a little cooler if you run lower wattage. It will still generate heat after a while since you are running in FM mode. I would try to put some heat sink compound on tR51. Sometimes they skimp on that at the factory. TR51 gets warm anyway so the more heat you get away from it the more st...

speedracer6g

Sorry I might have that wrong I will check that agian and get back to you.

MIKE

speedracer6g

does the radio have any RX audio?

speedracer6g

Radio Make and Model: Cobra 148 GTL D PCB Number: PC-332 PLL Number: 8719 Test gear available: Motorolla r-220b service monitor, Freq counter, Scope, Digital and Analog VOM, ect. Symptoms: This Radio had the ERF2030 mod and I guess it never worked and that is why i ended up with it. I got everyting ...

speedracer6g

Radio Make and Model: Cobra 2000 GTL PCB Number: pc-497aa PLL Number: 8719 Test gear available: Motorolla Service monitor R-2200b, Freq Conter, Digital and Analog VOM, Ect... Symptoms: I am having trouble alligning the sideband on this radio. I can get the tx to line up perfectly but as soon as i go...

speedracer6g

never mind this. The radio is fine. Aparently this radio will not work with a Mag Mount antenna. At least that is what Galaxy told me. Dont shoot the messenger here Aparently Galaxy said that the 949 and 959 have the same problem. And the rx and tx works fine all the time also the customer had me co...

speedracer6g

Dx94hp I have a new DX94hp here in the shop. It is brand new out of the box and when it is cold outside or the radio is just cold itself here on the bench it will not RX. I have ruled out a cold solder joint because this is the second one in a row that has done this. Has anyone else seen this before...

speedracer6g

Does anybody have a working frequency conter board out of a cobra 2000gtl. I am looking for one for a base i am working on. The one that is in it is reading 94.200 mhz. Radio is working fine along with the clock.

thanks!!

speedracer6g

Radio Make and Model: cobra 148 gtl-d PCB Number: kepc-332-e6 PLL Number: 8719 Test gear available: scope, comm analyzer, ac/dc meter , freq gen/counter ect. Symptoms: No tx in am mode ,ssb ok in tx and receive. pa working in ssb mode but not in am mode. Rx works in am mode just no carrier or mod. W...

speedracer6g

Ok then I am not worthy, I get it You have some years on me. Ha Ha :lol: Then that leaves me wondering a little then what is gm? I know for bipolar transistors it displays Hfe gain. What is gm on my meter I was under the impression that the was the gian of the mosfet. You will have to excuse me i am...

speedracer6g

:roll: Well I dont know what to say to that I got the equipment here to do it and that is that. Non only do the numbers on my B&k model 530 transistor tester not lie my results dont lie either. I may not be Rick Jackson but I do have more knowledge than your average guy. I have 15 years of exper...

speedracer6g

In all sincerity i give the you respect dogem. I learned from the old rf techs that had been doing rf work for 30+ years like yourself and i am sure you can work on an old tram or golden eagle like nobodies business. I dont hate the 1969 finals i use them too. I agree alot of people out there want m...

speedracer6g

The only reason i can see that cobra and uniden havent is due to the fact that they can afford to make the changes or that the cost is higher to go that route. I guess that cost probably the issue there. Ranger took advantage of the mosfets because there boards were actually realy easy to make the c...

speedracer6g

I have the kits that will work with the 11.3258 crystals so i think i will just lift the 10 pin of the pll and put in the 11.3258 crystal and use that kit. I checked my suplier for the crystals i need to do that mod and they dont have them so i will just change the crystal and mod the pll. thanks gu...

speedracer6g

Sorry got the wrong one it is an 11.1125 crystal. I know that the 11.325 crystal is .150 up and down from 11.325. Is it the same for 11.1125.

MIKE

speedracer6g

its a 142gtl radio. the mixer crystal is 10.24mhz and the pll is a mb8719.

thanks

MIKE

speedracer6g

I am building a b kit and need the crystall information for that model. I dont have one here in the shop to compare it to. Any information would be appreciated. I already looked at cbtricks too.

Mike

speedracer6g

Hi guys thought i would chime in on this discussion. heres my 5 cents worth of information. Bipolars have a lower gain than mosfets that is not new news to anybody. That is a plus compaired to bipolars. I will use either one but my favorite is the mosfet because you do get more power out of it compa...

speedracer6g

SWEEEET

thanks Scott for the tip I will have to put that one in my notes. It was c186 by the audio chip. Must of been shorted out I replaced it and it is all good now.

thanks again,

MIKE

speedracer6g

I Injected audio befor the pot and everyting works from the point. It seems like the audio is muted or squelced up but cant find where thing are fudged up. transmit works fine. when i put rf into the radio via my service monitor with 1kz tone i get receive on the meter but no sound. I will check the...

speedracer6g

TO santafe308 EMAIL ME AT mike@dibertselectronix.com

speedracer6g

I also checked tr43 and there is 0v on all legs on tx and rx. Also the pcb # is PC-412

speedracer6g

This radio has transmitt and no rx. the needle moves with rx but no audio. I checked the audio chip and it is fine I injected a signal into it and i have audio on the speaker. I checked tr13 and tr12 and the voltages are as follows. TR12 B 0V, C 8.19V, E .72 TR13 B 8.24, C .66, E 8.24 I also checked...

speedracer6g

If i ever forgot to thank you Rick I am sorry. Thanks for all your help. It is nice to have a go to guy that has alot of experience. thanks again for all your help. Keep up the good work.

MIKE

speedracer6g

I found out the company i work for has them we just dont have them in stock yet. We are currently getting rid of our rm itally boards first then we are going to those k100 units. I am sure we can get you one if you need them pm me for more info.

MIKE

speedracer6g

Sorry, nevermind me i found out what i needed to know thanks.

MIKE

speedracer6g

I was looking at new products on cbtricks.com and there is a nice kit for an onboard amp. Does anyone know where to get them?? here is the link to look at the setup.

http://www.cbtricks.com/Amp/k_line/k100/index.htm

speedracer6g

got it going rick thanks for the help. bad diode.

thanks,

MIKE

speedracer6g

thanks

speedracer6g

I am ordering some plls from cobra but and wondering if anybody knows what pll chip it is. The part on the chip just says cobra 25ltd. But what is it? I am looking to save a few bucks by bypassing cobra. If anyone knows please fill me in.

MIKE

speedracer6g

Well i found the problem. I must of bought a bad batch of 2sb827 transistors. I went back to the 754 that was in it and it worked fine. So i installed a 827 that i knew was good and now everything is just fine. that is what i get for ordering from a guy in china. Lesson learned. I check the Hfe gain...

speedracer6g

where are the smoothing caps??

speedracer6g

ok here goes.

TR49 B 7.5 C 11.5 E 7.35
TR50 B 11.5 C 7.3 E 11.75
TR51 B 11.75 C 7.3 E 12.95
TR52 B 7.0 C 11.6 E 7.0
TR53 B .85 C 7.8 E 1.8
TR54 B 0.0 C .5 E 0.0

R243 46.6 OHM
R241 9.7K

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

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