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

sorry hotrod, forgot to update, yes, got it going. Only a blown track from the middle leg of the smaller transistor (q153) bolted to the side casing, just down from the audio i.c. No other faults found. Apart from 2 blown output trannys' 2sc1969 in this case, and replacing the above mentioned compon...

thanks zodiac, that part checks out ok. closer inspection revealed a burnt out track between q153 and the audio i.c. Will post exact position soon. Once repaired it fired up beautifully. No other apparent damage!!! Other problem is low output power, less than 1 watt on my dummy load, but have been t...

hi all, happy new year to everyone. I've been asked to look at a magnum delta force that apparently has had the centre pin on the mike plug shorted out (dodgy mic soldering by the sound of it!!), A couple of wires inside the plug were touching, including the centre one, and now he tells me that radi...

recently aquired a huntron tracker. looks like a useful bit of kit. sort of got the jist of it but has anyone out there gotta copy of the user manual?? wishful thinking i know, but you never know!!!

cheers rick, all new trannies in the radio now and biased up no probs, worked on ssb for 10 minutes with no distortion at all. problem was probably a combination of faults. cheers for the info and the use of the site!!!

cheers rick, the tranny was hot enough for me to pull my finger away a bit sharpish got the bias set up though but didn't want to do any more till i heard back from you. will check those parts tomorrow and post results asap.

sorry rick, it was tr46 (c2086) that was getting hot, not tr45, i'm an idiot!! do you know of a replacement for this transistor?? or could something else be wrong causing this tranny to heat up?? Also noticed that tr's 48,53 have been replaced with c710's but not put on the board as the markings say...

cheers rick, i'll swap it out and let you know results.

Hi All, update on that troublesome cobra. Replaced all components that rick advised. replaced 1n4007 with old stock (after checking them) thermal diodes from junked out CRT 3900. Finally managed to bias up the outputs as per the service manual but now tr 45 (c2086) is getting very hot to the touch. ...

Hi Beakster, try Chris at mode componants for spares, if they're not in his catalogue, give him a ring, he's very helpful and reasonable prices.


www.modecomponents.co.uk

hope you fix it, alex

should i use a little bit of heat-sink compound between diodes and transistors?? I will replace all of those componants to be on the safe side, thanks again rick, i will post results a.s.a.p found r267 dead short up to yet, more results to follow. only got 1n4001's in the spares box so gonna get som...

Thanks Rick, i'll try that tomorrow. by the way, the diodes attached to the output transistors, are their values critical? should they be the same and can you recommend a replacement?

cheers, Alexthegasman

Hi, could anyone tell me why this 148 gtl-dx (pb010) wont let me bias the output?? Passed on to me by a friend with ssb garbled, thought it would just need biasing but it wont let me! usual suspects have already been replaced by someone else (pcb screws, Tip42c) so i'm at a loss. Fault, low mic gain...

Hi there, just a quick word of hello and thanks from myself, Alex, in the uk. This forum has helped me solve problem a with a tricky cobra 148 gtl-dx ssb audio fault (hopefully, when the parts arrive!!). A big thanks to all who post, a great site!!!