Search found 432 matches

by The Defpom
Sunday 6th Jun 2010, 0:18
Forum: CB Radio Repair and Troubleshooting
Topic: Cobra 148-GTL issues
Replies: 7
Views: 4003

Re: Cobra 148-GTL issues

Hi, You would still need to align the radio after the conversion to AU, not only the frequencies, but you would also need to align the TX and RX sections as well, as they will likely be tuned for best performance on NZ. You would need a 7 digit frequency counter to correctly align the frequencies, i...
by The Defpom
Saturday 5th Jun 2010, 23:54
Forum: CB Radio Repair and Troubleshooting
Topic: Cobra 148-GTL issues
Replies: 7
Views: 4003

Re: Cobra 148-GTL issues

That is funny, I get people giving me Cobra 148's to convert from 27 to 26MHz, it almost seems a waste to convert one back ! Basically the NZ mod involves changing a crystal (X3) to drop the radio down by 635KHz (from 11.325MHz to 11.1125MHz) , however, once that crystal has been changed, all you ne...
by The Defpom
Saturday 5th Jun 2010, 23:35
Forum: CB Radio Repair and Troubleshooting
Topic: President lincoln display/audio fault
Replies: 26
Views: 14283

Re: President lincoln display/audio fault

There should not be a connection from the MPU (the large chip) to the speaker, are you sure it is soldered, and the wire has not just come off and lodged between a couple of pins ? Lincolns can be hard to troubleshoot, I have repaired many of them, it usually requires a frequency counter and oscillo...
by The Defpom
Tuesday 27th Apr 2010, 15:47
Forum: CB Radio Modifications
Topic: Adding TX/RX LED to Lincoln
Replies: 7
Views: 7419

Re: Adding TX/RX LED to Lincoln

You could just use a flip flop type transistor switch pair, and feed that directly from the mic TX line, which is 0V when in TX, nice and simple. Yes there are points you could connect to, in order to pick up the RX and TX only voltages, off hand I cant name them, but there is a PNP switching transi...
by The Defpom
Saturday 20th Mar 2010, 20:45
Forum: CB Radio General
Topic: Kudos - Dave Zodiac
Replies: 6
Views: 4766

Re: Kudos - Dave Zodiac

here here!
by The Defpom
Monday 8th Mar 2010, 7:49
Forum: CB Radio Modifications
Topic: MC145151 PLL
Replies: 15
Views: 11935

Re: MC145151 PLL

Hi Dave, Hopefully we can get to the bottom of it. Pin 28 should be connected to 0V through a 220pF ceramic cap to help load down the LD output (minor detail) You have the 8V and 0V markings back to front on pins 2 and 3, pin 2 is 0V, pin 3 is 8V. For 10KHz spacing you want RA0 and RA1 to be low, an...
by The Defpom
Sunday 7th Mar 2010, 9:13
Forum: CB Radio Modifications
Topic: MC145151 PLL
Replies: 15
Views: 11935

Re: MC145151 PLL

Hi Dave, I have used that PLL with an EPROM, only I moved all the inputs over by 1 bit, and set it for 5KHz steps, then the lowest bit can be manually switched to give a 5KHz shift. It is a very versatile PLL, and is able to be configured for many different situations, negative and positive going PD...
by The Defpom
Saturday 6th Mar 2010, 8:55
Forum: CB Radio Repair and Troubleshooting
Topic: Midland 76-900 internal PSU fault
Replies: 6
Views: 3816

Re: Midland 76-900 internal PSU fault

The usual culprit that dies in that power supply is the main current regulator, Q201, sometimes I have found the Zener diode dead (ZD1, ZD2), or Q1. To answer your question, you could use a different diode there OK, as long as they can handle the current they will be OK, as the voltage is low anyway...
by The Defpom
Friday 5th Mar 2010, 14:12
Forum: CB Radio Repair and Troubleshooting
Topic: Galaxy 98vhp deadkey 250 watts on ssb???
Replies: 9
Views: 6261

Re: Galaxy 98vhp deadkey 250 watts on ssb???

Good to hear that you found the fault.
by The Defpom
Thursday 4th Mar 2010, 10:39
Forum: CB Radio Repair and Troubleshooting
Topic: Galaxy 98vhp deadkey 250 watts on ssb???
Replies: 9
Views: 6261

Re: Galaxy 98vhp deadkey 250 watts on ssb???

Then it is likely to be something around the BM, I would start by checking the power supplies and switching, Q34 does the switching, it may be leaky so it is not switching off properly, also check C149, C144, C146, C145 after that you will just have to check each resistor around the IC, R172, R174, ...
by The Defpom
Wednesday 3rd Mar 2010, 11:08
Forum: CB Radio Repair and Troubleshooting
Topic: Galaxy 98vhp deadkey 250 watts on ssb???
Replies: 9
Views: 6261

Re: Galaxy 98vhp deadkey 250 watts on ssb???

I would be looking at the balanced modulator first (IC6), to make sure that it is filtering out the sidebands and only providing an audio carrier, and then go from there.
by The Defpom
Friday 19th Feb 2010, 22:08
Forum: Scanners
Topic: pro 2006
Replies: 7
Views: 13522

Re: pro 2006

I know this is an old thread but in case anyone finds it searching for the same symptoms, I found the cure. Simply replace the batteries, then RESET to Factory Defaults - Both Realistic Pro's I've owned are reset by holding the 2 and 9 buttons down then turn on - you will lose all stored frequencie...
by The Defpom
Friday 19th Feb 2010, 22:03
Forum: CB Radio Alignments
Topic: SWR meter
Replies: 1
Views: 2478

Re: SWR meter

It is not really needed, FS stands for Field Strength, it is used to check the radiation pattern of the antenna, I have never used one, and am not really sure it is of much use anyway, personally I think it was just a bit of a gimmick.
by The Defpom
Thursday 18th Feb 2010, 7:17
Forum: CB Radio General
Topic: Am I slowly killing my radio?
Replies: 2
Views: 3308

Re: Am I slowly killing my radio?

Mag mounts are not ideal, as they are really meant for temporary installations, or ones that require the antenna to be removed frequenctly (such as places that have low height access etc. that said, as long as they are tuned then it will work just fine, it wont be a performer, but it will work. You ...
by The Defpom
Saturday 13th Feb 2010, 23:39
Forum: CB Radio Repair and Troubleshooting
Topic: SUPERSTAR 360FM EPROM
Replies: 38
Views: 22850

Re: SUPERSTAR 360FM EPROM

You will just have to adjust it and watch the voltage, like I said in my earlier post, aim for about 7V on the highest channel the radio has got, and check that you have at least 1V on the lowest channel the radio has got. The slug could need to be turned either way, as it depends on where it is set...
by The Defpom
Saturday 13th Feb 2010, 15:52
Forum: CB Radio General
Topic: Sound Module Pre-Keyup info required Please.
Replies: 9
Views: 8218

Re: Sound Module Pre-Keyup info required Please.

0V, zero volts, the earth trace.
by The Defpom
Saturday 13th Feb 2010, 15:35
Forum: CB Radio General
Topic: Sound Module Pre-Keyup info required Please.
Replies: 9
Views: 8218

Re: Sound Module Pre-Keyup info required Please.

It may be possible, but it would require that the switch design currently uses the 0V line, the only way to know for sure would be to open up the unit and see if one of the wires goes to the 0V trace inside it, if it does then you could connect the other wire to the TX line and see if that does the ...
by The Defpom
Saturday 13th Feb 2010, 13:50
Forum: CB Radio General
Topic: Sound Module Pre-Keyup info required Please.
Replies: 9
Views: 8218

Re: Sound Module Pre-Keyup info required Please.

The switch may need to be replaced using ONLY the wire connections provided, using another source of supply may damage the unit, or the radio, it is best to keep them completely separated from the radio wiring unless it can be clearly seen that one wire is just the 0V rail. The other three wires are...
by The Defpom
Saturday 13th Feb 2010, 11:57
Forum: CB Radio Repair and Troubleshooting
Topic: SUPERSTAR 360FM EPROM
Replies: 38
Views: 22850

Re: SUPERSTAR 360FM EPROM

Yep, you need to adjust it, make sure you use the correct size screwdriver to avoid breaking the core.

Monitor the voltage on CH40 and adjust the VCO until it reads 7V, then recheck on CH1 of the lowest band to make sure you have at least 1V there.
by The Defpom
Saturday 13th Feb 2010, 10:13
Forum: CB Radio General
Topic: Sound Module Pre-Keyup info required Please.
Replies: 9
Views: 8218

Re: Sound Module Pre-Keyup info required Please.

You didn't exactly wait very long... 11 hours is hardly enough time to expect a response, maybe people were asleep, or at work, or out. In my case I was fixing a radio, then a I went to sleep... My guess for your requirment would be to make a small relay switching circuit, to replace the push button...
by The Defpom
Saturday 13th Feb 2010, 9:55
Forum: CB Radio Repair and Troubleshooting
Topic: SUPERSTAR 360FM EPROM
Replies: 38
Views: 22850

Re: SUPERSTAR 360FM EPROM

The easiest way is to just pick it out with a small screwdriver, put it to one side, once adjusted, put it back in a remelt it.
by The Defpom
Sunday 7th Feb 2010, 23:47
Forum: CB Radio Repair and Troubleshooting
Topic: SUPERSTAR 360FM EPROM
Replies: 38
Views: 22850

Re: SUPERSTAR 360FM EPROM

I would actually say to check the voltage at TP2, watch it when you go from CH10 through to CH40 on the UK band, and see if the voltage stops changing once you get to the channels which are not working, the voltage you see is used to control the VCO frequency, and comes from the PLL, it can only pro...
by The Defpom
Saturday 30th Jan 2010, 14:16
Forum: CB Radio Modifications
Topic: new cobra 25/channel mods?
Replies: 7
Views: 4550

Re: new cobra 25/channel mods?

Yes, he has authored a few books, and service manuals.

For more info about the mixer, if he still has it on his site, go to :http://www.cbcintl.com
by The Defpom
Saturday 30th Jan 2010, 9:14
Forum: CB Radio Modifications
Topic: new cobra 25/channel mods?
Replies: 7
Views: 4550

Re: new cobra 25/channel mods?

The PLL generates different internal N codes for its frequency divider between TX and RX, so the board to replace the PLL must do the same. Lou Franklin designed a mixer circuit which switches the radio from low side to high side injection (or vice versa), and allowed a conversion my by mixing in a ...
by The Defpom
Friday 29th Jan 2010, 22:56
Forum: CB Radio Modifications
Topic: new cobra 25/channel mods?
Replies: 7
Views: 4550

Re: new cobra 25/channel mods?

The PLL is a ROM type, they cannot be expanded. The PLL is the same as a TC9106 except that the inputs are inverted. I have successfully done a band swap to one of these, to convert it to NZ channels, but it is not something that most people would be able to do, I designed a board years ago to repla...

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