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mosfet mod for old style 148gtl

loosecannon

loosecannon

Sr. Member
Mar 9, 2006
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can someone who has done this with consistent results give me the specifics of the mod?

the one generally found all over the net is for the new style 148's, and i would just like to know what, if any differences there are in doing this to the old style chassis.

oh, i have read that some dont recommend mosfets for SSB radios.
i talk a lot of SSB when the sunspots are rolling, and dont want to ruin my audio or otherwise detract from the great SSB sound of this chassis.
so, is it ok?
will it "warble" me?

thanks for any info,
loosecannon
 

seedkey said:
this mod is only for the new style with 4 pin front microphone jack.
Click to expand...

I see that now ;)

It still will work if some one who knows what they are doing
works on the radio.
(Older 148)
 
this is the purpose of me asking the question.
i am not a technician.
i do not want to experiment with my rudimentary skills on a classic chassis.
i would like to hear from someone who has done it to more than one radio and has gotten consistent results. or if consistent results can actually be obtained.
i cant be the only one who has asked this question.
can i?
loosecannon
 
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Reactions: Hambone388
148 mods

I've been doing these in my shop for almost 2 years now. Old or new same deal, no changes. I've not had any problems as long as I absolutely soldered everything well.

Also must think through the circuits and know which side of what we are using. The biggest problems I've had, were thinking I'd done something, that after redoing it and looking, I actually hadn't been right the first time.( Hope you followed that!)

I would suggest the single mosfet mod for your first several and then maybe a dual final.
I've usually been seeing a little less than others (watts wise), but they really work. I've had 2 that went over 50 watts with a single mosfet. Never did figure out why, ( both were early Malasian). Bird 43 pep meter and Dozy tfc 3001p, so the meters agree give or take a watt or 2.
Very easy to overdo the modulation for SSB so I recommend an osciliscope. I make sure the modulation isn't being over done and showing a curve and no clipping, or spiking.
A quality noise cancelling mic goes a long way with these also.
marven
 
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Reactions: Sniper1977
Re: 148 mods

marven said:
I've been doing these in my shop for almost 2 years now. Old or new same deal, no changes. I've not had any problems as long as I absolutely soldered everything well.

Also must think through the circuits and know which side of what we are using. The biggest problems I've had, were thinking I'd done something, that after redoing it and looking, I actually hadn't been right the first time.( Hope you followed that!)

I would suggest the single mosfet mod for your first several and then maybe a dual final.
I've usually been seeing a little less than others (watts wise), but they really work. I've had 2 that went over 50 watts with a single mosfet. Never did figure out why, ( both were early Malasian). Bird 43 pep meter and Dozy tfc 3001p, so the meters agree give or take a watt or 2.
Very easy to overdo the modulation for SSB so I recommend an osciliscope. I make sure the modulation isn't being over done and showing a curve and no clipping, or spiking.
A quality noise cancelling mic goes a long way with these also.
marven
Click to expand...

I never leave home with out a oscilloscope :)
every unit i am into ,I use a signal generator
Freq counter , a true RMS Volt meter and my coaxial dynamics meter..
about 50watts ain't to bad for a 148 ..I am going to try that mod with my new swing kit I summed up..I got it to key up 1watt swinging 27 so far without the mosfet..
 
lords, and marven,
thanks both of you so much for the responses.

glad to know it works.
the SSB thing is the reason i was hesitant to do it. the 148gtl sounds so good on SSB i didnt want to mess with that.
dont own an O-scope yet, and probably wont for another year or so.

i think i'll leave the 148 alone for now, as its the only one i have.

thanks again,
loosecannon
 
loosecannon said:
lords, and marven,
thanks both of you so much for the responses.

glad to know it works.
the SSB thing is the reason i was hesitant to do it. the 148gtl sounds so good on SSB i didnt want to mess with that.
dont own an O-scope yet, and probably wont for another year or so.

i think i'll leave the 148 alone for now, as its the only one i have.

thanks again,
loosecannon
Click to expand...

ya ya thats a good idea :)
mine is stock and well has my own swing kit installed (n0t the internets one) but not a mosfet setup...
I am working with a new batch of irf's but i ain't going to post nothig yet..all i am going to say is for a 1.99+tax there 20watts ones :)
 
cobra 148

I've been getting mine from Mouser for .60 cents each.
marven

P.S. The ones I experiment with, that is. :shock:
 
Whats this world coming to ? Those mosfets got to be the hottest item going on nowadays !! They work ! that's for sure. 4 x 520s will get you 50 to 200 peak without a sweat ! Italy has been using them cotten pickers for years already !! Whats really going on ? somebody finally catching on here :) There already making amps out of them , putting them in radios everytime I turn around . SOB !! Could this be a MOSFET World ? :) 60 cent part that makes the teches 60.00 a pop !! YEAH BABY !! Bring them on while the getting is good I say. :) or should I say PUMP IT UP !! already. Leave that sweet 148 alone and buy yourself a decent AB-1 amp.......or maybe even a mosfet amp. :) good to hear folks are getting those DK's up from them. Hmmmmmm
 

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