Copper Talk » Ask The Tech » Radio's Mobile » Once R131 is cut, Should I jump it or leave it alone? « Previous Next »

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Jameslarson
Intermediate Member
Username: Jameslarson

Post Number: 350
Registered: 4-2006


Posted on Tuesday, May 01, 2007 - 8:19 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

OK, I cut R131 on my Grant. should I leave it be now, or should I now put a jumper in it's place? Thanks.

PS- I may even just put a 4.7 K resistor instead, but let me know about the jumer either way. Thanks./
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Kid_vicious
Senior Member
Username: Kid_vicious

Post Number: 2519
Registered: 9-2004


Posted on Friday, May 04, 2007 - 12:30 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

i know it seems like if 10k is good, and 4.7k is better, that 0 ohms would be the best. (a jumper)

i thought this too until i asked pat00 about it and he explained it to me.
i wish i could remember what he told me.LOL

i do remember that you do NOT want to jumper it.
just remove it and be done with it.
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Patzerozero
Senior Member
Username: Patzerozero

Post Number: 3666
Registered: 7-2004


Posted on Friday, May 04, 2007 - 6:42 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

did i say to EXPERIMENT with values for r131....or put it on an external pot....or switch several resistor values for best sound....131 is for AM modulation-you can make it LOUDER then stock, without completely removing r131. BUT the 8719 chassis is possibly the most acceptable to total removal of that resistor. you have a mic gain, so as KV said 'just remove it and be done with it'-and adjust as neccessary. the simplest mods are sometimes the most effective.
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Jameslarson
Intermediate Member
Username: Jameslarson

Post Number: 359
Registered: 4-2006


Posted on Friday, May 04, 2007 - 10:20 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I actually put a 4.7 k in there. Works good
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Kid_vicious
Senior Member
Username: Kid_vicious

Post Number: 2521
Registered: 9-2004


Posted on Sunday, May 06, 2007 - 12:25 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

how did the swing mod turn out?
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Jameslarson
Intermediate Member
Username: Jameslarson

Post Number: 366
Registered: 4-2006


Posted on Sunday, May 06, 2007 - 8:34 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Radio cranks great. Dead keys 1.5. Swings over 7 in AVG mode. almost 20 in peak. Perfect for the 667 now. I went to town on the radio. RX mods, TX mods, q24 center leg mods, CAP mods, you name it, if it was on the web, I did it. All I have to do now is upgrade the finals.
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Im4jc
Intermediate Member
Username: Im4jc

Post Number: 237
Registered: 11-2005


Posted on Sunday, May 06, 2007 - 9:26 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Why upgrade the finals if you are going to be using it with the 667? 20 watts pep is pushing it as it is.

Man, I'm maxing out my 667V with my Grant and it's only doing about 14 or 15 watts PEP.
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Dale
Advanced Member
Username: Dale

Post Number: 838
Registered: 12-2002
Posted on Sunday, May 06, 2007 - 10:20 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

yea disabling the limiter is why hes doing so
much pep.15 sounds good.those other mods im not
sure whats involed but disabling the limitr is one i would not have done,vr7 is the audio adjustment and ya should be able to get plenty
just out of that and lower the carrier with the right vr and thats it
dale/a.k.a.hotrod
cef426
cvc#64
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Kid_vicious
Senior Member
Username: Kid_vicious

Post Number: 2524
Registered: 9-2004


Posted on Sunday, May 06, 2007 - 10:43 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

cool!
glad you're happy with it.

as for upgrading the final and driver; it can be done; it may produce a few more peak watts, and its very expensive to do.
check the price for a MRF477 transistor.

if you are thinking about doing the ERF2030 mods, they have not been perfected in the 148gtl's, and always seem to require some tweaking after its done to get it right.
i have heard mixed reviews about how suitable the MOSFET's are for SSB radios.
if you really wanna do it; get a cobra 29LTD and go to town. ive heard these radios can do 40 watts+ if done right.

i also think you are very close to the max. PEP input to the 667 already.

far be it from me to advise someone against modding their radio; just do lots of searches for others experiences first.

have fun,
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Jameslarson
Intermediate Member
Username: Jameslarson

Post Number: 367
Registered: 4-2006


Posted on Monday, May 07, 2007 - 8:23 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I do notice the radio does get hot now on the back plate. I may also upgrade the main Cap in there too. It certainly could not hurt.
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Unit199
Intermediate Member
Username: Unit199

Post Number: 468
Registered: 8-2003


Posted on Monday, May 07, 2007 - 1:19 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

When you push radio that hard it cannot help but get hot and the final life is going to be cut down.
HARVE
UNIT199
CEF210
CVC18
KB0YVK
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Jameslarson
Intermediate Member
Username: Jameslarson

Post Number: 368
Registered: 4-2006


Posted on Monday, May 07, 2007 - 4:17 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Yes, That is why I am going to upgrade the final. Want the radio for a long time. ;-)
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Patzerozero
Senior Member
Username: Patzerozero

Post Number: 3683
Registered: 7-2004


Posted on Monday, May 07, 2007 - 5:50 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

i wouldn't mess with it while it's working good, though i don't know why you should be feeling noticeable heat at that amount of power. get a piece of heat sink material, or even a couple pieces of 1/8" aluminum stock from home depot. bend like this: |___| then another smaller |__| and a 3rd, |_|, put each inside of each other & bolt to back of radio chassis centered over finals. that'll work as a heatsink, too.

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