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

found problem a transistor in keying circuit was shorted.

have a problem.Northstar 9000.If the radio is keyed up and you turn back the RF gain you will loose power.If you remove tr17 it will fix this problem. The receive on AM is not very good either.On SSB it work fine.D15&D16 have been replaced.

how many watts are you putting into the amp.If you are putting more than 4 watts into the amp or if your radio has a swing kit put in it,you are probably clipping the signal.

IC 4 is a voltage regulator.yes it is goiing to get a little hot.I would get a can of circuit coolant and cool down the board(do a small portion at a time to see if this is a thermal problem that you are having).once you have found the area that the radio sarts working you will have to spay each par...

I will post the fix as soon as I Finish the Gray 400. I was looking at some diagrams of an amp that is close to this one.I beleive that someone has been in this amp and removed parts to make it look like it is putting out more Power.example at the input of the amp after the relay, the signal is fed ...

I found the problem the radio is back in the big rig working fine.This is the first time that I have had the dynamic control go bad.I can usualy clean the control and that would fix it. This time it was bad.

check you 10.240 crystal.it might have a cold solder joint.re solder that to see if that might fix your problem.

check all the screws that mount the board to the chassi.I want to say there might be a solder tab that is connected to the chassi,check to see if that might have a cold solder joint. hope this might give you some help.

does the needle move like it is receiving?

if you have the part side of the radio and the front of the radio faceing you D79 is towards the front of the radio on the right right across from the board mounting screw.It looks like it is to the right of a plug.D80 is below the same plug.If you have any circuit cooling spray, cool the diodes and...

replace diode (D79) & diode (D80)and see if that fixes your problem.the part # is 1N4148.this is a switching diode.tell me if this fixes your problem

I have already done that i replaced both of the caps that you are refering to.I'm using a sing wave generator and i'm inserting the tone at the collector of tr18 wich is rather loud.I'm goiing to look at C74 ceramic cap to see if this might of gone south. thanks for the reply.Woody

Have A cobra 29 Ltd With DIsorted audio put evey thing back to stock 3watt dead key no foward swing,checked & replaced final (final checked good ).when i talk it sounds bad.Help

I have a gray 400 that has a standwave problem.When i have it on low power the standing wave is low 1.1or1.2 when i put it on high power the standing wave goes over 2.5. I have tried it on other ant. and I have the same results. any help would be great.One other thing is that I took a 667V and hooke...

I would check the eletrolitic caps in the circuit these will be located next to the audio amp (ta 7222 ap) wich is located on the right hand side the the parts side of the board IC8.C151 4.7MFG,C150 22MFG.sometimes these caps dry up or leak.if you have an ohm meter check to see if they are shorted

check the 10.240 crystal this is located over by the mb8719 pll chip I have found this crystal to be bad or it could be a bad solder joint.

I might want to tell you that rf parts does have a minimum order of $25.00. Look them up on the net @ RFParts.com you will see what the minimum is.

The driver is you problem.the part #is RD16HHF1.The only place I could find it was at RF Parts,they are around $4.00 each. this part is located to the left of the 2290's.I would also get a new insulator that goes on the back of the transistor.

ok,I found the problem D81&D82 where bad.If you check them with an ohm meter thay cheched good.when the radio was on and i cooled them down the radio started working fine,Replaced both diodes 1N4148 and radio is now working great. I thought i would put this out here in case ther is another radio...

what kind of mic are you useing on this radio?

on the pc 244 vr5 is the modulation adjustment vr10 is am power vr11is SSB power adj. Check to make sure that vr5 is not turned down.

i have checked and replaced tr 36-tr37-tr38.If i leave the radio on ,the radio will start to tx by itself. I have used some freez spray in that area of those tr's.I'm goiing to replace two switching diodes to see what happens.

I have a connex 3300 the tx&rx lights are both on,there is not a mic pluged into the radio they are still both on check diode 77 checks good . :