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Cobra 139XLR and a 142GTL
- Thread starter DelR
- Start date
They are completely different.
The 139 XLR uses the uPD858 chassis, which has the older 4 pin mic connector and uses a relay to switch between receive and transmit. The 142 GTL uses the MB8719 chassis, which has a 5 pin mic connector and uses electronic switching. Also the 142 GTL has a little chrome strip on the front vs the black one on the 139 XLR.
They look so much alike because Cobra was too cheap to design a new box when they switched to the newer (142 GTL) model.
I only own one Cobra and it's a 148GTL from the 90's, with the 8719 chassis. A very fine radio for sure. However, if I was faced with the choice of a 139XLR or a 142GTL I would take the 139 any day of the week....
I love the 858 chassis as it's much more frequency agile than the 8719 chassis. 858 chassis can go from 26.085 way up into 10 meters with the full mod and is easy to broadband. Most an 8719 chassis will do is 26.815 to 28.045 and performance really suffers at the top end.... Just my few cents worth......
I love the 858 chassis as it's much more frequency agile than the 8719 chassis. 858 chassis can go from 26.085 way up into 10 meters with the full mod and is easy to broadband. Most an 8719 chassis will do is 26.815 to 28.045 and performance really suffers at the top end.... Just my few cents worth......
I agree 100%. The 139XLR (Uniden 858SSb chassis) is by far the better of the two. It was only produced for 3 years ('76 - '78). I run a 139xlr that I bought new. Best Cobra base ever. Because it could be easily modified to exceed FCC limits for output power, modulation, and frequency range, its manufacture was discontinued due to pressure from the FCC in late 1978.
- 399
Arguably the best bang for your buck SSB 40 channel CB chassis ever made.
1306/1307 combo that easily will do 25 watts - runs rings around a 1969 or 2312, built in compression so the stock mic would produce full output, easy to expand and broadband. The only area where it might lag behind a 8719 chassis is in the NB department. Even then, put some Schottky's in and retune.
You will want to recap it.
1306/1307 combo that easily will do 25 watts - runs rings around a 1969 or 2312, built in compression so the stock mic would produce full output, easy to expand and broadband. The only area where it might lag behind a 8719 chassis is in the NB department. Even then, put some Schottky's in and retune.
You will want to recap it.
139XLR, President (4-pin) Washington, Robyn SB520, President (4-pin) Madison are all 1978 radios. Didn't get made after that year because the FCC insisted on making it harder to get illegal channels. The PLL chip and channel selector in the 1978 radios could not meet the 1979 rule changes.
Chip technology, analog chip technology was advancing by leaps and bounds at the time. You wouldn't think that one year would mean much, but the 1979 "GTL" series Cobra radios were redesigned, with PLL chips and channel selectors that were harder, but not impossible to expand coverage. All the circuits in the post-1979 radios are different, with different analog chips in them.
The FCC tightened the rules again soon after, making it even harder to get extra channels, but older radios that had been approved for legal sale after 1979 were "grandfathered" and still legal to make and sell. This is one reason that a radio design from 1979 like the Cobra 148 or Uniden Washington was still being made decades later. Imagine Detroit offering to sell you a car with 1979 design and 1979 parts in it. The Cobra 148 was easy to expand beyond 40 channels, so the model got "rolled over" to the next year for decades.
A radio that says "GTL" on it will be newer than any 1978 radio, but possibly not by more than a year. The 139XLR and similar radios used single conversion in the receiver. Some folks like this design, others not so much. The later GTL radios were built both ways. The Cobra 142GTL, Uniden Washington, Tram D300 had single-conversion receivers. The Uniden Madison, Cobra 148 and 2000 have a double-conversion receiver with a filter that narrows the receiver's bandwidth for sideband, and gives the AM receive side a crisper sound, with a filter for AM only that's wider than the 1978 radios.
And when considering an antique for restoration, the miles matter more than the years. A 40 year-old radio needs electrolytics. How much more than that it will need is usually a
wear-and-tear issue.
Too bad it doesn't come with an odometer.
Somewhere between 25 and 40 years of age, a radio passes beyond the "repair" age and reaches "restore" age.
Replacing only the electrolytic caps that are causing trouble today will become a game of electronic whack-a-mole, as they fail one or two at a time year by year.
73
Chip technology, analog chip technology was advancing by leaps and bounds at the time. You wouldn't think that one year would mean much, but the 1979 "GTL" series Cobra radios were redesigned, with PLL chips and channel selectors that were harder, but not impossible to expand coverage. All the circuits in the post-1979 radios are different, with different analog chips in them.
The FCC tightened the rules again soon after, making it even harder to get extra channels, but older radios that had been approved for legal sale after 1979 were "grandfathered" and still legal to make and sell. This is one reason that a radio design from 1979 like the Cobra 148 or Uniden Washington was still being made decades later. Imagine Detroit offering to sell you a car with 1979 design and 1979 parts in it. The Cobra 148 was easy to expand beyond 40 channels, so the model got "rolled over" to the next year for decades.
A radio that says "GTL" on it will be newer than any 1978 radio, but possibly not by more than a year. The 139XLR and similar radios used single conversion in the receiver. Some folks like this design, others not so much. The later GTL radios were built both ways. The Cobra 142GTL, Uniden Washington, Tram D300 had single-conversion receivers. The Uniden Madison, Cobra 148 and 2000 have a double-conversion receiver with a filter that narrows the receiver's bandwidth for sideband, and gives the AM receive side a crisper sound, with a filter for AM only that's wider than the 1978 radios.
And when considering an antique for restoration, the miles matter more than the years. A 40 year-old radio needs electrolytics. How much more than that it will need is usually a
wear-and-tear issue.
Too bad it doesn't come with an odometer.
Somewhere between 25 and 40 years of age, a radio passes beyond the "repair" age and reaches "restore" age.
Replacing only the electrolytic caps that are causing trouble today will become a game of electronic whack-a-mole, as they fail one or two at a time year by year.
73
Thanks for that great information. I recently purchased a 148 GTL with the 5 pin mic on the side, with manufacture date of 1994 on back. I am glad BC mentioned this radio, because it was my next question. Now I am in the market for a Cobra base.
Just bought a Cobra 139XLR. Got to wait for it to get here. Next advice I would like to ask for is antenna. Maco VQ3 V-Quad or Maco 4 element vertical beam? (I had the 4 element in 1991 with my last radio, which was a cobra 89, and it talked great, but would like some input on that new v-quad.)
It depends if your primary interest is talking long-distance (skip), or if you are mostly a local talker. The V-Quad is horizontally polarized so it would be a fantastic antenna for skip. It's basically a beam made of delta loops. I run a homebrew delta loop here.
The vertical Maco beam will be a killer antenna for local, but not so much for skip as skip signals propagate better horizontally and many folks shooting skip use that polarization.
If you talk both local and skip you really need two antennas. This is why you often see a horizontal beam on a tower with a vertical groundplane mounted above. Right now I am using the horizontal delta loop for skip and an Antron 99 for local talking.
This is why the old Moonraker beams rocked..........both vertical and horizontal polarization in one antenna. They were very good directional antennas and it really is too bad nobody makes them anymore. Old ones in serviceable shape are almost impossible to find now, especially out here on the coast where everything corrodes after a few years outside! PDL-2 was another antenna I remember that could be set up for either vertical or horizontal. I haven't seen a functioning one of those for years either.....
The vertical Maco beam will be a killer antenna for local, but not so much for skip as skip signals propagate better horizontally and many folks shooting skip use that polarization.
If you talk both local and skip you really need two antennas. This is why you often see a horizontal beam on a tower with a vertical groundplane mounted above. Right now I am using the horizontal delta loop for skip and an Antron 99 for local talking.
This is why the old Moonraker beams rocked..........both vertical and horizontal polarization in one antenna. They were very good directional antennas and it really is too bad nobody makes them anymore. Old ones in serviceable shape are almost impossible to find now, especially out here on the coast where everything corrodes after a few years outside! PDL-2 was another antenna I remember that could be set up for either vertical or horizontal. I haven't seen a functioning one of those for years either.....
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I had the VQ3 till a windstorm snapped my weak rotor and threw it to the ground.
Loved that thing once I got it sorted.
People thought I was on a much more expensive beam. (I have no locals so everything was skip) Then a tornado hit me last week and wiped my VQUAD (among other house and vehicle and property damage) which I think was a year old if that. I'm buying yet another VQUAD with out a second thought. Excellent little antenna. Not as much gain as big brother VQ3 obviously but this time didn't snap my cheap rotor so I'm sticking to the much lighter VQUAD. If your mounting arrangements can handle the bigger antenna go for it I don't think you will be disappointed. It was also pointed out somewhere on the forum the VQUADs (and thus VQ3) have a higher "take off" angle which supposedly gives some benefit over standard beam designs for long distance. Others with more technical expertise than myself can no doubt add to this.
Loved that thing once I got it sorted.
People thought I was on a much more expensive beam. (I have no locals so everything was skip) Then a tornado hit me last week and wiped my VQUAD (among other house and vehicle and property damage) which I think was a year old if that. I'm buying yet another VQUAD with out a second thought. Excellent little antenna. Not as much gain as big brother VQ3 obviously but this time didn't snap my cheap rotor so I'm sticking to the much lighter VQUAD. If your mounting arrangements can handle the bigger antenna go for it I don't think you will be disappointed. It was also pointed out somewhere on the forum the VQUADs (and thus VQ3) have a higher "take off" angle which supposedly gives some benefit over standard beam designs for long distance. Others with more technical expertise than myself can no doubt add to this.
Yes, I am interested in skip and not so much local. The gain is rated at 14.5, wit power multiplication of 27x, which seems good for the size and weight. The maco 4 element is 14db gain and power multiplication of 28x. I will use a cheaper style rotor, seeing I cant afford another Hamm II style rotor, just yet, anyways. I am excited about getting this thing up on my 40ft tower and getting things rolling, or skipping, I should say.
Also, CopperElectronics sells a Maco Shooting Star 8 element, which looks like the MoonRaker, 4 vert and 4 horiz, with the same power multiplication of 28, which makes me like the VQ3 design better, because of the weight. The only thing that worries me is the "wop sided" design not being balanced on the mast like a regular beam.
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