I wish a lot more people would watch your video's and actually learn something. The amount of times i've had to explain things like this and why you don't crank AM audio up full and power. And the ALC and why spreading coils don't increase your power And why you get back swing on AM with some cheap power meters (they've never heard of PEP). And trying to align a radio with just a screw driver and with (ears) that must have built in SINAD, If it was this easy we would all just own a screwdriver and not lots of test equipment plus special alignment tools.
thats a spectrum conversion board witch give you the uk FM channels 27.60.1 to 27.99.1 fitted many back in the day and a switch with a 1k reristor for the alpha channels
fairly sure the beep was on the main board. The Mk1 had the same sound design as the Hygain V - the ascending tone with amplitude inversely proportional, while the Mk2 had a steady 'nasa' tone.. the Mk1 beep switching transistor would fail, so they changed the design in the Mk2. That UKFM freq mod board (used in combination with the open clarifier/VFO to get the UKFM channels) and that horrible multi-tone beep board are all evidence that this radio lived in the UK for some of it's life. Nice to see it's still alive, great classic radio. An object of desire for anyone who was active in the 80's..
I used to do EPROM mods on the gtl dx and superstar 360fm to give the UK 27/81 band, +10KHz shift and to also give high high, and low low bands. I actually looked very closely to see if that was one of my EPROM modules! (It isn’t). That radio must of originated in the UK, I recognize the bleep board, I used to mod those to give 9 tones.
@@mikesradiorepair One of the important things the EPROM board did was to order the channels 1-40 so that there were no gaps and they were sequential without the 23 jumble as we used to call it of course the 148 gtl dx could already go to all the channels if it had a 10khz and a 5khz tuning tx/rx shift it was just a bit of a palaver finding them all quickly The EPROM solution made it so much more user friendly and of course the classic annoying 5 tone roger beep didn't. I preferd the dah di dah beep. best regards Sean
Very common radio over here in England. Those eproms were used to add the uk cb band. When in high band (normally) switch in the eprom to add 27.60125 - 27.99125 (UK 1-40) Definitely looks like it would have been imported from the UK.
17m30s...back in the day there was a frequency meter everyone used and the power input was fine for that bnc socket. Galaxy fre meter i think it was and it gave the correct freq readout on SSB too.
3:16 My mod chip has been clipped and I'm not having any problems whatsoever, and it was done in the early 90's, in fact I've gotten a lot of compliments, but I'm also using a Astatic 575.
+metclapton If you mean for a double tone SSB adjustment then any two audio frequencies that are not harmonically related like 700/1900, 400/2500, 850/2200, etc...
I can see that your resolution bandwidth is a little too wide for this type of work ... have the same problem with my Agilent which only goes down to 1kHz which isn’t any use for this kind of work I reckon yours must be about 300Hz ?
I wonder if using a piece of grey or orangish film over that bright cold white display on the spectrum analyzer would make it show up better on camera?
Hi. Do you do mail in repairs? I have a cobra 148, cobra 29ltd and uniden pc68ltw that need work and alignments. The 148 was working great untill i put a car battery charger on the battery while operating radio. Replace fuze but Now whenever i power on it blowes fuze immediately
A very common trick was to use a slider. A Cobra 132 I used to have was modified with a slider that could easily slide over 2 channels at the bottom of the band and over 3 at the top. It let me use the entire band as well as adding a couple of channels at the bottom(below channel 1)
I'm not a great fan of the roger beeps, with one exception, that is the standard Ham International roger beep, otherwise known locally as the NASA beep
I wish a lot more people would watch your video's and actually learn something. The amount of times i've had to explain things like this and why you don't crank AM audio up full and power. And the ALC and why spreading coils don't increase your power And why you get back swing on AM with some cheap power meters (they've never heard of PEP). And trying to align a radio with just a screw driver and with (ears) that must have built in SINAD, If it was this easy we would all just own a screwdriver and not lots of test equipment plus special alignment tools.
legendary radio in the UK Mike
Mikes radio repar you utube videos are awesome
Another informative video! Thank you Mike for your time and sharing with us. Joel
mike people should leave mods to someone like you for you know your stuff I had a Cobra 148GTL DX 50 years ago great radio
thats a spectrum conversion board witch give you the uk FM channels 27.60.1 to 27.99.1 fitted many back in the day and a switch with a 1k reristor for the alpha channels
fairly sure the beep was on the main board. The Mk1 had the same sound design as the Hygain V - the ascending tone with amplitude inversely proportional, while the Mk2 had a steady 'nasa' tone.. the Mk1 beep switching transistor would fail, so they changed the design in the Mk2. That UKFM freq mod board (used in combination with the open clarifier/VFO to get the UKFM channels) and that horrible multi-tone beep board are all evidence that this radio lived in the UK for some of it's life. Nice to see it's still alive, great classic radio. An object of desire for anyone who was active in the 80's..
probley the best selling SSB radio in Europe at the height of the hobby.bullet proof sets
Mikes radio repar cobra 2000 gt dx am/fm/ SSB 40 channel
Is awesome
I used to do EPROM mods on the gtl dx and superstar 360fm to give the UK 27/81 band, +10KHz shift and to also give high high, and low low bands. I actually looked very closely to see if that was one of my EPROM modules! (It isn’t). That radio must of originated in the UK, I recognize the bleep board, I used to mod those to give 9 tones.
+TheDefpom
Yeah it's a neat vintage beep board. Matches the vintage EPROM board.
@@mikesradiorepair One of the important things the EPROM board did was to order the channels 1-40 so that there were no gaps and they were sequential without the 23 jumble as we used to call it of course the 148 gtl dx could already go to all the channels if it had a 10khz and a 5khz tuning tx/rx shift it was just a bit of a palaver finding them all quickly The EPROM solution made it so much more user friendly and of course the classic annoying 5 tone roger beep didn't. I preferd the dah di dah beep. best regards Sean
I like your video's! You take the time to explain things in detail. 73,
Very common radio over here in England. Those eproms were used to add the uk cb band. When in high band (normally) switch in the eprom to add 27.60125 - 27.99125 (UK 1-40) Definitely looks like it would have been imported from the UK.
This may have been a Cobra 148 GTLDX from the UK, as the EPROM would have been set for the UK legal 40 FM. Very common mod here in the UK.
17m30s...back in the day there was a frequency meter everyone used and the power input was fine for that bnc socket. Galaxy fre meter i think it was and it gave the correct freq readout on SSB too.
We still have the factory service manuals for the 148 gtl dx
3:16
My mod chip has been clipped and I'm not having any problems whatsoever, and it was done in the early 90's, in fact I've gotten a lot of compliments, but I'm also using a Astatic 575.
Good Rig !
What were the two freq that you used then? When i adjusted my MK2 cobra the power was low then properly adjusted like 3W. Thanks for video
+metclapton
If you mean for a double tone SSB adjustment then any two audio frequencies that are not harmonically related like 700/1900, 400/2500, 850/2200, etc...
Thanks i will try this and see what i get and thanks for the RX signal tracing video using a spec analyzer that was useful vid
I can see that your resolution bandwidth is a little too wide for this type of work ... have the same problem with my Agilent which only goes down to 1kHz which isn’t any use for this kind of work I reckon yours must be about 300Hz ?
I wonder if using a piece of grey or orangish film over that bright cold white display on the spectrum analyzer would make it show up better on camera?
There are tone generator apps for smart phone users, also.
i had one of those beep boards once I hated it sold it off. and ya' i have a 148-dx really good radio
Hi. Do you do mail in repairs? I have a cobra 148, cobra 29ltd and uniden pc68ltw that need work and alignments. The 148 was working great untill i put a car battery charger on the battery while operating radio. Replace fuze but Now whenever i power on it blowes fuze immediately
try checking the protection diode on the power input line, it's probably shorted.
replace the protection diode across the power terminals inside the radio,
They could've just put the 10khz switch to get the missing channels.
A very common trick was to use a slider. A Cobra 132 I used to have was modified with a slider that could easily slide over 2 channels at the bottom of the band and over 3 at the top. It let me use the entire band as well as adding a couple of channels at the bottom(below channel 1)
I got this radio but no roger beep mike it look nice radio no switch for missed channel it stock
I'm not a great fan of the roger beeps, with one exception, that is the standard Ham International roger beep, otherwise known locally as the NASA beep
Great video. How do i contact you in regards to my cobra 148gtl. Thanks Brian.
You are not going to get rich doing their warranty work then......