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

speedracer6g

I have done this mod and it is a little tricky to get it right. First i would not use the ERF2030 use the IRF520N. DO NOT USE ANY OTHER IRF520 MAKE SURE IT HAS THE SUFFIX N. If you use any other it will not work properly. then just go by the dx-33hp schematic to math up all the other stuff. I get 10...

speedracer6g

I found a definite problem with modding these. YOU HAVE TO USE IRF520N MOSFETS NO OTHER SUBSTITUTE WILL WORK. I tried the IRF520V mosfet i that i have been using in my cobra mods and well they dont work for crap. All you can get is about 40 pep if your lucky and the audio is distorted a little. Just...

speedracer6g

Yes that is a good idea. I had planned on doing that i am going to take my time and get it all to gether as soon as i can. I did another one today and found that without the 2sb827 you notice a big difference in power output. Well thanks again. Since you been so helpfull have you messed with the ran...

speedracer6g

Well finally got it giong. I was having a blonde moment and forgot to move the exta capacitors from the bottom of the board. Duh!! Well with that and the 2sb827 and all the other stuff being done it works better than the new DX-33hp. I got 29 watts average on the meter on my R2200B comunications ana...

speedracer6g

If you are using an onboard linear you will need to sheild the board. If not it will bleed rf all through the board and well you found out what happens. to verify this take the radio apart with this board moved away from the radio. if it quits wich most likely it will that is your problem. I would r...

speedracer6g

You should go through an allignment to get the full benifit of this mod. I have seen good improovemnts with this mod. I always see better results after the allignment though. Cheers

MIKE

speedracer6g

hey I may need one of those also. I had one in the shop a few monthes ago and couldnt find one anywhere. Do you have any left???

MIKE

pm me if you do.

thanks,

mike

speedracer6g

I have an update on the upgrade to the 2sb817. I used one the other day without looking into it and well it has lower gain than that of the 754 and the 827. So stick with the 827 it has higher hfe gain than the 817. Now i have to unload these things to somebody who needs them. I guess that is the sc...

speedracer6g

Your Coax and antenna is the most important part. I would recomend using rg8. Cushcraft makes a reasonably priced Coax that has very good specs. there are many manufacturers of coax and prices and specs vary. one spec you want to go by is db loss per 100ft. here is some specs on the stuff i use. Not...

speedracer6g

From what i have seen of the strykers they dont have very many toys on them and they are a rebranded magnum anyway. I standard peak and tune with R178 changed to a 1k resistor will get you 50 watts clean out of a 3300hp. and that mod will not void your warranty. This mod came right from galaxy's tec...

speedracer6g

Sorry forgot about the recieve kit that is just a 2sc2999 and some different diodes i forget the number off hand. works well just throws off the rx meter a bit. I havent had time into looking into that issue yet. for this you do need a signal generator and a ac meter to do an allignment or you will ...

speedracer6g

It should be the relatively the same as a 29ltd. Here is how i do them. -Remover R55, ,56, and C61 -Remove TR14 and Install IRF520N use a mica insulator if you have one and dont forget the heat sink compound. -Install EN1230 AtR56 with positive mark facing twoard R123 or the front of the radio. -Rem...

speedracer6g

what final is being used in the driver section at Q74? If it is the rd6hhf1 it is only a 6-10 watt driver you will need more than that do drive the new transistors. I would like to see this work though.

MIKE

speedracer6g

I was looking at the data sheets for the two transistors. The only Difference i see is the collector output capacitance is about 200pf higher wich isnt a big obstacle i would think, however the higher drive that it requires is a different story. You may want to look into upgrading the driver to a mo...

speedracer6g

I agree with all the info above. One thing I do is set the bias with a 10k pot or 100k wichever you may have. I attach one of the legs to the positive side of C116 and the other to the gate of your IRF520. This is the far left leg looking at the front of the mosfet. Then put volt meter the gate and ...

speedracer6g

I would stick with a IRF520N myself they are cheaper and you get the same results.

MIKE

speedracer6g

Hey I also found that the dx 98vhp mainboard has dual mosfets on it. so you could use this to do the mod also. just folow the schematics from that.

MIKE

speedracer6g

Oh In the manual it says to set the driver at 3.8 and the finals to 3.6volts. I will change that. I put the 2SB754 back in and did pick up a couple of watts . I can now key 10 and swing to 21 wats avg. I am getting 40 PEP on my bird now. Almost there!! I was looking at the 2sb827 and it has a higher...

speedracer6g

AARRGGG. well I am getting about 8 watts deadkey i can turn it up to 12 but It is peaking out at 32 watts pep before it starts to flat top the waveform. It is like i am not getting enough drive from the audio to push it the rest of the way or something. tr51 is getting pretty warm real fast. On my c...

speedracer6g

ok did that and that helped alot. the am regulator is getting pretty hot still. I am not sure if it is supposed to get that hot I never noticed that before. I have to change those caps yet. I am going to change the two resistors also. I will let you know how it goes. I am getting 10 watts deadkey an...

speedracer6g

oh geez the things you miss. Cant see the forest for the trees. I will try that out here in a bit. I will get to it as soon as i get this boat anchor 98 vhp off the bench.

MIKE

speedracer6g

That goes to show you what kind of people there are out there looking to take advantage of ignorant people. Its sad i think. Something tell me he wont be getting good feedback.

MIKE

speedracer6g

ok well i didnt change out those caps yet since i will have to order them. I could not find them on mouser or digikey. i might have to call them. Anyway i will post an update to what i did tonight. -REPLACED TR44 WITH IRF520V -REPLACED R218 WITH 10K -REPLACED VR11 WITH 100K POT -REPLACED R219 WIH 47...

speedracer6g

Its funny what poeple will sell on fleabay. all hail the joemaster cap. ha ha thats funny. If he get 60 watts plus swing i must be walt disney. thanks for sharing.

MIKE

speedracer6g

ok here goes: I left the driver stage alone. this was due to the fact i couldnt get the bias voltage below 4.2 volts. so anyway everything behind tr44 is normal. -Replaced tr56 and tr43 with irf520V mosfets. -Replaced D112 and D88 with 5.6 volt zener diondes. 1N4734 1 Watt these were replace in reve...

speedracer6g

Well this is an interesting one. I have a galaxy dx 33hp and this other galaxy 88hml. both with the 3600 series boards. i went through the dx 88hml and updated everyting in it to match the 33hp's mosfet setup. in the end the am regulator gets pretty warm and it only puts out 18 watts. verses 17 with...

speedracer6g

thanks anyway i got the skinny from the galaxy tech at wwdx forum heres the schematics he sent me. i am just going to use this to make up my own mod. thanks.

http://www.cbtricks.com/radios/galax.../dx959_sch.pdf

http://www.cbtricks.com/radios/galax...mosfet_sch.pdf

speedracer6g

I am trying to find the dual mosfet upgrade for the dx 949. I dont care much for the ekl version i never have any luck with them. Anybody have info on the new mosfet versions of this radio. any schematics would be greatly helpful.

MIKE

speedracer6g

Watt readings vary by make and type of meter. Also that could of been 32 watts on a dosy or one like it and the 60 watts could of been from a bird 43p meter. dosy says its a peak meter but it realy isnt. I would trust the $600 bird wich is industry standard before i would trust anything else. on my ...

speedracer6g

Not bashing anyone but i agree with the fact that cutting limiters is bad there is usually more than enough ajustment for more modulation especially on this radio. Cutting limiters will only show you false power readings and distort the radio grab a scope and look at it. I know that it looks like yo...

speedracer6g

just a thought did you check for any cold solder joints. Also check the am regulator. I would start by keying the radio and flex the board a little bit with you finger and see if you audio comes back intermittently. I would have to look at the schematic to be able to tell you much more. I will see i...

speedracer6g

I just purchased some of the pcn-60 and the 203 boards from rm italy for my radio shop. I did a trial install on one of my spare cobra 29ltd's. And like some one said rf shielding is badly needed to make them work properly along with about a 1 watt deadkey with some serious swing to get any power ou...

speedracer6g

yep no problem got er done thanks agian

MIKE

speedracer6g

this radio has no internal speaker. But i did find out from looking at the schematic that you are right about the audio. they route the audio though the mic. this unit has low receive with no mic on it also. this led me to beleive there was a short to groung somewhere in the audio distribuiton. went...

speedracer6g

Well hopefully i can save someone alot of headaches. I traced the problem to the headphone jack. I didnt have the insulated washer and was somehow grounding enough to let some audio through the speaker at all times. so could be a bad cap in the mic jack. but i just put a nylon washer behind the jack...

speedracer6g

It has the external speaker only. the problem seems to be audio is getting back in the speaker. looking at the schematic the mic should turn the rx audio off when you key up but somehow there must be a leaky cap or something to ground somewhere. it still has a low level rx without the mic hooked up....

speedracer6g

Working on this tram d300 solid state radio same as the cobra 142 or washington base. it has talkback but it is not supposed to have talkback. cant find any resistor jumped to add talkback. replced a couple questionable caps in the audio section but i am still getting talkback. anyone ever had this ...

speedracer6g

Well i have found the problem. someoe thought he would put a 390ohm resistor in line with the rf gain pot. for some reason i missed that, it was hidden in the bundle of wires. Dont know what they were thinking but anyway after all that messing around that is all it was. thanks for all the help rick....

speedracer6g

ok I checked and replaced both r48 and c20. Both were ok but i replaced them anyway. checked ops and no luck. checked the 1st mixer frequency and it is 16.714 on CH40 and 16.270 on CH1. I checked fet1 and it is ok. I also replced c11 and checked c9. I noticed something interesting though when i jump...

speedracer6g

Thanks Rick your a big help I will check them later. I did finally check my fet and it is fine so i will look at the other issues you told me about.

thanks,

Mike

speedracer6g

I am working on a cobra 29 ltd. Checked the radios receive and found that the audio dosnt clean up until around 7-8 uV on the service monitor. Tx is fine. I checked R31 and it was fine I replaced anyway for PM. I replaced D1, D2, D4, D5, D6 and Tr7. Still no luck. I noticed when running through the ...

speedracer6g

Sure can!! -instead of using a 4.7k use a 10k pot or 100k. set your gate voltage to about 2.7 to 3volts. Do this by putting a voltmeter on left most leg of the mosfet final when looking at the face of the transistor. -remove C45 -remove C46 and install a 480pf capacitor. Also do not put a jumper on ...

speedracer6g

I have power on the pll and at the power switch. i loose power at the pll chip when i key the radio. i removed the audio chip and it still drops power as soon as i key the radio even with tr 24 removed. would a bad pll chip like ic2 cause this problem????

Mike

speedracer6g

I am working on a texas ranger tr-127fs radio the face lights up and the channel display lights up as soon as i key the radio the led display goes out. it does this on cb and pa i checked b+ at the pll and it drops to zero when you key the radio rx also does not work. no audio on pa either. tried to...

speedracer6g

well i am going to answer my own question here. Just found the problem i found that D70 was cut and it was hiding under the wiring by the echo board. well maybe this will help someone else who is trying to fix up someone elses snip and clip job.

MIke

speedracer6g

I have a galaxy dx-77hml that is overmodulated and flat topping on the scope. I fixed tr-53 and the tr32 and removed the swing kit. i looked until i was crosseyed and i cant find anything else that was hacked up. i checked a couple transistors in the amc circuit and they all check ok. the modulation...

speedracer6g

Are all the channels off or is it just one?

speedracer6g

yep i just signed up i wont get full access for a while i guess.

MIke

speedracer6g

thanks for the schematic it wont let me download it so i will have to try and set up an account. i got it figured out now it was in programing mode or something it is actually a 10 meter rig havent worked on one before. I now need a mic pinout diagram. I have deadkey but no modulation and i think th...

speedracer6g

Have a roadpro titan 2 no tx or rx when i key up i get an EE on the lcd display. i dont have a serivice manual so i am kind of stuck. i am not sure if it is supposed to have a EE on tx or if it is an error code i am thinking it is an error code. any help would be great. If anyone knows where i can g...

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

Search found 165 matches

galaxy dx 88hml dual mosfet upgrade help???

Need Galaxy dx 949 dual mosfet upgrade not ekl version.

Cobra 142gtl /Tram D300/washington base talkback problem????

Cobra 29ltd Poor Receive

texas Ranger tr-127fs no tx or tx

Galaxy DX-77HML Overmodualted help

MAGNUM 257 ROADPRO TITAN 2 NO TX OR RX