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

frogman296

i use a salt water dummy load

http://www.qsl.net/k5lxp/projects/SaltL ... tLoad.html

frogman296

you know...i never thought of it in that aspect...makes sense...stupid me

frogman296

did you check the mode switch? i know it sounds simple...but

frogman296

soldering iron??

watt meter??

what do you have on hand to assist you in tuning

frogman296

does this in any way affect the amount of background noise the mike may pick up??

frogman296

should get more than that.... heck the reg s9's will do those numbers

frogman296

cbtricks.com for the alignment procedure

cobra 25 is the same

want mods...google uniden 68 mods.... net is full of lil hack tune tips

frogman296

defpom...thanks

reason i am so intrigued by this mod... a local had a 148 that would slide a full 10khz down... was having issues with it on ssb... i suspect this is the reason why it was acting so goofy on ssb

once again thanks for setting me straight.

frogman296

angusuk wrote:hi brian,thanx for the help
that seems a good idea can i just change the ic10 as in desolder KIA6410S then replace with Toshiba TA7310,

is this just the simple replacement job?

frogman296

this mod intrigues me... i have been trying on and off to get "channel 44" i want 10kHz slide down... 1. Remove D51 and put in a jumper. 2. Install a "super-diode" in place of the stock varactor D35. 3. Add a 4.7uh to 10uh choke to the banded-end of the stock varactor. here are t...

frogman296

anybody?

frogman296

Do you have audio in PA mode ? If not trace all the way from the audio pin on the mic socket through to the main PCB, and confirm that there are no shorts or missing connections, a solder blob could kill the audio entirely, even with connections being correct. no audio in pa mode... i get some &quo...

frogman296

It sounds like you have the radio in the PA mode or AMC/ALC transistor TR24 is turn-on, try removing C110 and see if it is now working, if not try removing TR24 and see if it is now working. TR24 is used to shunt the mic audio to ground, this is part of the ALC and AMC, and if this transistor is fu...

frogman296

Radio Make and Model: COBRA 148GTL PCB Number: PC416AA PLL Number: MB8719 Test gear available: bird meter, BK2040 sig gen, multimeter, freq counter Symptoms: radio has rx and tx on channel 1 and 20 What is working: only channel 1 and 20 work on the receive and transmit. radio is showing the watts it...

frogman296

Those green axial type are the ones you would want. A warning though, adding a inductor to the varactor has some tradeoffs, firstly, it gives you more down slide than up slide, and it also then requires you to re-align the loop oscillator section, it can also increase LSB instability and cause more...

frogman296

The 10KHz switch is only to give you the A channels 3A, 7A, 11A, 15A and 19A, and the channel switch giver you the rest. What was you expending to get? can this mod be done in addition with the "2 switch" channel mod for the mb8719?? the switch on pin 10 and the switch between pin 11 and ...

frogman296

Varctor is D35. Adding a 5.6uh choke to the anode will also increase slide range further. just curious... this choke you speak of... is there any certain style i should get?? i see some on ebay... 5.6uh axial choke.... http://i19.ebayimg.com/01/i/07/62/45/cb_1_b.JPG http://i1.ebayimg.com/08/i/001/1...

frogman296

which mod do you recommend rick??

frogman296

thanks very much

the new look is great and the search function works..

again thanks for a wonderful forum

frogman296

Could not delete old search id sessions

DEBUG MODE

SQL Error : 2006 MySQL server has gone away

that is the message i get when i try to search... have tried both firefox and IE

any suggestions

frogman296

okay i have a cobra 148 gtl...mb8719....

i want to put this radio on frequency...a question i have...

where are the test points?? i cannot see them on the board.

is there anybody who has a list of all the test points, and their locations, for this radio??

frogman296

i know this topic is a bit old....but i have here a cobra148gtl that is all garbled on ssb transmit

all screws, holding the pcb to the chassis, are tight.

however...there are no caps from the chassis ground to the chassis earth...any ideas??

should i replace the ssb filter in this?

frogman296

i picked up one of these radios...it makes a loud tick tick tick tick noise(rx and tx)....but when i push on the transformer area of the board, it stops..

anybody have this problem....the radio is in decent shape..im thinking a cracked solder on the board

frogman296

personally...i would sooner risk mailing it to a reputable cb shop, than taking it to a truckstop shop. not saying all truckstop shops are bad, but.

frogman296

http://www.rfparts.com/transistors_2SC.html#1906

frogman296

i find a 33 ohm to work the best..

frogman296

DWB wrote:My god man,was that soldering done with a fireplace poker?? Buy some real soldering equipment like Antex.

thats not called for...and this was charity work...before and after pics were shown, and there was a decent job done on my part.

frogman296

did you ever have any luck with this radio...i am having similar problems

frogman296

the radio is working perfectly as of now...i have "road tested" it...

frogman296

timrim wrote:What is the current at both test points?
It is possible that either the control burnt out again or there is something else in the bias circuit that is blown.

showing no current at both test points

frogman296

Actually its not the voltage you are trying to adjust its the final current. You remove the jumper pc board and connect an amp meter between posts, you need to set the driver current and final current, when doing this go to USB with mic gain fully off. Final Bias - Connect DC Ammeter between TP7 an...

frogman296

the pot that i replaced, was for the bias voltage for one of the finals...when i adjust, nothing happens..

i followed the instructions, on cbtricks, for adjusting the bias voltage...but to no avail..

frogman296

voila....it worked....many thanks timrim...i cant say thank you enough...now i can get this disaster out of here

frogman296

Here is the board layout, I marked where the transistor leads go. On your last picture, the ball of solder is just to the right of your red circle about even with the bottom of the circle about half inch. that lil blob was just a lil pece of slag...it wasn't on there when i was testing the radio.. ...

frogman296

i was thinking that those legs were out of place as well....but...i had to verify...thats the way that the fella had put the new ones in.. 2166 driver and 1969 finals....i replaced the diodes, and it still shows continuity on the final closest to the driver i have no spare 2166's on hand, so i will ...

frogman296

before

after

frogman296

this radio has no forward power...i replaced the driver and finals...after rebuilding the traces as best i could.....the radio shows modulation, but absolutely no wattage. as you can see in this pic..i have drawn an arrow to the pot(VR10) and resistor(R241) that was smoking when the radio was powere...

frogman296

hmmm...i have been retracing all steps...the wire from the volume control...just may be the mistake i made...

frogman296

http://cbtricks.com/radios/cobra/29ltd_ ... 1_pg11.pdf

on page 11...the component side of the board...i have decided to try this again...any help would be appreciated...

frogman296

capacitor and resistor..couple dollars max for the parts

frogman296

well...a fella had dropped off 3 radios...to be repaired...he said they just wouldn't turn on at all...so i checked em, replaced the diodes in them except the one with the clipped diode(what inspired this topic). i asked him if he had hooked em up backwards, he said that he hadn't but said when he w...

frogman296

just curious....i replace em all the time....but i had one here that somebody had clipped the diode, and a fella hooked it up wrong...

thanks for the info

frogman296

this, lil question, basically applies to the cobra/uniden 40 channel cbs. i know the whole protection principle must be very similar in most cbs. i have seen these radios that have been hooked up incorrectly, resulting in a blown reverse polarity diode.....some just cut the diode and fire the radio ...

frogman296

the wire that goes to pin number 2 should be wrapped in the bare(shield) inside the cord..

the bare(shield) goes to pin 1

from what im hearing..pin 3 and 4 may be mixed up

frogman296

volume/squelch pot...worth a try...if your dynamike pot is shot, more pots may be in the same condition

frogman296

Rick wrote:This is because you have done something wrong.
Make sure the collector of TR17 is connected to C37.

okay..near as i can see...i have lifted the wrong leg of c37.

i have decided to scrap the radio...but...i am going to use this radio to hopefully perfect this mod.

frogman296

mosfets and 1969s are like apples and oranges.....if you have a erf2030 in there now...i would leave it...unless you really want to replace the 2166(3.95@rfparts) with a 1969(9.95@rfparts)

frogman296

stay away form those mobile beams...they are complete junk...stargunn junk

the best coil antennas out there...10K on 55 antennas.....magnet mount, wilson 5000.

what vehicle??

frogman296

im assuming you have the older version...you can replace the final...kind of like putting perfume on a pig though....not worth the cost of the final for small gains.

frogman296

well...i tried this...and now i have no swing..

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