Cobra 200 GTL DX

 

COBRA 200 GTL DX

 

Back Ground

This is the new Cobra 200 GTL DX, the SSB/AM/FM hi power Cobra recently released in the USA. It did not take long for it to become the radio that “everybody loves to hate”! I couldn’t see why. If you looked at the price then looked at the specifications, no other radio comes close…30W on AM/FM/CW and 100W on SSB, Antenna warning light, SWR meter, 6 digit counter, echo, roger beep, Hi /Low power switch, NB/ANL, and coverage (Once modified) from 26.065 thru 29.695.  The cheapest 100W 10m/11m SSB on the market is running around US$380.00 on up. Why did cobra price this one at US$229.00? On spec alone it should sell for US$350 minimum if they were trying to break into the market. Seems a bit more at stake here. Cobra is making a statement and we must all be wondering just how much we are being ripped off on SSB CB radios today? Obviously Cobra must be making money…they did not release it at this price to go broke! Unfortunately user reports on this radio have not been all good. The audio on SSB seems to be the problem. Regardless I had to have a look and see what Cobra was up to releasing a new 10m radio at the low point in the sun cycle. Doesn’t get much worse on 10m! Why didn’t they make a 40m 100W mobile for a couple of hundred dollars for the car…Now that would probably sell well at the moment!

 

Out of the Box

After waiting over a month for Fedex to clear a couple of these Cobras and a President Lincoln out of customs I eventually loaded up the wallet and drove out to the airport warehouses to do it myself. 3 hours later and a little bit lighter in the wallet I was speeding back to the house with the three radios.

One of the cobras had been opened by customs so I opened that one first.

First impressions. The box is impressive. Well constructed and excellent artwork. Designed to catch the eye. The box and the radio say they are constructed in the Philippines. I believe Cobra has a factory just out of Manila somewhere. This is a heavy radio. Finish is good and the heat sink from the back running down and underneath looks both effective and attractive. Heavy duty. First thing I did was pull the lids off. Had to see what it looked like inside!

The serial number on this was H506000270. No date.

 

As you can see the 100W PA stage is mounted on the main motherboard. Output transistors on this radio were the HF-50. I heard the new ones coming out had the 2290 finals and had specifically requested this but ….I wonder about the wisdom of placing the 100W PA stage on the main board. All amateur radios keep the PA stage well separated from the rest of the radio. Never seen inside a hi power Galaxy or ranger so I wonder if they do the same? Seems a huge potential for RF into the rest of the circuitry and all those resultant problems. But if Ranger and Galaxy can work it out then so can Cobra.

 

The boards look neat and lots of tiny components that I could hardly see with my eyes.

The speaker is huge also. The insert in the microphone looks like something out of an old telephone!

 

 

The heat sink wraps around the radio and protrudes about 2cm under the cabinet.

 

The speaker is really that big!

 

The microphone is huge and I was forever bumping my lips with it.

 

 

 

 

Front Panel

 

 

 

 

 

 

 

 

 

 

 

 

The Front Panel is relatively uncluttered and everything seems easy enough. So just what is everybody on about!

 

First things first…We had better convert this puppy so we can get it up and running on 11m and show it off to all my mates. OK no worries ..cut R138 and bridge the pad in front of it. Specs on and go searching….There are no component markings on the board and most of the surface mount stuff is microscopic. Black dots on the green circuit board! On to the net and email Dave in the states who has modded his. Help, Urgent, Do you have a photo. Impossible to do this without a guide! A couple of hours later and the pic arrived….Had to study it for a bit…This one was not quite the same..close enough tho.

 

 

 

My one looked like the one above. Went ahead and pulled out the side cutters and destroyed the resistor and dropped a blob of solder across the 2 points above it. A quick check and 26mhz on the counter.

Lids on and hooked up to the dummy load to run some quick tests.

 

Frequency coverage. (Expansion mod done)

There are 4 bands A,B,C&D. Each band covers 90 channels. All in order including the alpha channels which read out correctly on the counter and are marked with a dot after them on the channel readout.

We have 27085.0 on the counter and CH 11 on the channel readout.

We have 27095.0 on the counter and CH 11. on the channel readout

Sure looks like a CB set to me!

 

Band                Frequency                    Talk                 Whistle

  A                   26.0650 – 26.9550       65W PEP         100W PEP

  B                    26.9650 – 27.8550      80W PEP         120W PEP

  C                   27.8650 – 28.7550      100W PEP       140WPEP

  D                   28.7650 – 29.6950      85W PEP         135W PEP

 

The -10kc switch does not appear to do anything.

 

 

ON AIR TESTS

 

First thing I found with this radio was that you can’t just put it down anywhere. The heat sink sticking out below the case means you have to prop up the front. Because this is a heavy radio the heat sink will mark what ever you sit it on if you leave it for long. I went back to the box and fitted the mobile bracket to it so it would sit up. Leans back on the heat sink but not too much..

The clarifier is in the wrong place for me. It is the third of 4 knobs and I always seem to go for the last knob which is the SWR Calibrate and echo. Received audio sounded tiny. With such a huge speaker they must have gone to a lot of effort to make it sound so sharp.

Everybody reports the transmit audio is too trebly. Clear but sharp. Just needs to get deeper somehow.

If nobody has heard you on the radio before they may not comment, but as all my testers confirmed it was not me and they did not like it. Need to try some other microphones and the mod listed below.

Cobra have released a fix for the 200 which involves adding a capacitor somewhere, but without a circuit diagram and a photo it would be impossible as none of the components on the board are marked. Impossible to find.

 

 

 

 

The Mod

 

 

 

 

TECHNICAL SERVICE BULLETIN

10043

 

 

MODEL(S):               150GTL, 200GTL  

 

DESCRIPTION:        Receiver overloads when receiving a strong signal, resulting in distorted audio.  In addition there may be a warble in the modulation when transmitting (which the customer might describe as a popping sound during transmit).

                                   

ACTION:                   RF is bleeding into the receiver front-end.  Apply the following fix:

 

                                    For both the 150GTL and 200GTL, install a 1µF electrolytic capacitor across C607.  (From C607 to ground)

 

                                                                       

                                               

 

 

 

 

 

 

 

200GTL

 

 

Scrape to expose the circuit traces as indicated above.  The large copper area is ground.

 

 

 

Solder the capacitor as shown.  Be sure to observe polarity.

Put some glue under the capacitor so that it cannot move.

 

 

 

 

Conclusion

Some how or other Cobra have managed to make a radio that is actually less than the sum of the total parts. It grows on you like a wart.

 It bugs you.. the big microphone, the poor audio reports, the round knobs that tell you nothing, the clarifier stuck between two other knobs and deciphering the dots on the channel selector to work out where in the in world you are today.

Its kind of like it was designed by a committee.

The workmanship is great but it was certainly not designed as an amateur rig even though it is being sold as such. It needs a better microphone and much better modulation. More watts we can get from anywhere but if it don’t sound good to start with it ain’t going nowhere

It is a 100W CB set.

No more no less.

And priced accordingly

A bargain for a CB’er but no amateurs and serious SSB’ers will touch it.

Even if Cobra sold this rig for a hundred dollars…until we can get that ‘telephone’ audio fixed it will be staying in the cupboard.

Come on Glen, lets see if you can make this thing come good without redesigning the entire audio department.

 

91DD018

Jakarta

Dec 3rd 2005

 

PS

 tried this thing on air to go down 5k/c’son the slide. The counter is way off down there. 540 became 541.3 on the cobra. Something is seriously wrong here. That has pretty well killed it in my book. Audio acceptable until listener hears something else.

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12 Responses to Cobra 200 GTL DX

  1. Unknown says:

    Well this looks like a nice radio but has the same problem as the RCI2970 suffers from.They will never be stable with the heatsink underneath the radio.Heat rises so it will only heat up the board and resulting instability, the bit sticking out on the back is not going to keep it cool.Try running a linear without having the heatsink at the top, feel the heat????If the heatsink had been on top that would have been good, on the bottom, thumbs down!!RF problems should never happen in a radio these days, but as you said its build for price and this is what you get.Pity, maybe they\’ll get it sorted, too bad if you got one now and have to muck around with it to make it work properly.Never mind Master Tester, more radios to go, more tests to do, Glen will buy a new soldering iron and put them all into shape, big iron to go with the big heatsink.Catch you later, Aja

  2. Michael says:

    Well, I had the first version, and being diplomatic, I was very impressed by the build quality of the box! Now I have a so called Rev3, BF version, I added a couple of temperature switched fans to the heatsink to keep things cool, and I agree with the previous comments as I recall the early 2970 CPU going nuts due to over heating, today you can flip the front panel and have the heatsink on the top. Anyway, the other mods I did to the 200 was to add some ESD protection to look after the driver mosfet. There are various was of doing that, a couple of zener diodes wired back to back across gate and source, or two suitable diodes wired back to back with an inductor to cancel out their pf, one clamping on negative spikes, the other on positive spikes. I chose the latter working in harmony with the antenna static bleed resistor, and after some seven months of ESD type weather, the driver has not succumbed and the test considered a success. Why didn’t Cobra fit these few components, but then the same question might be asked of Icom, as not a few of their state of the art rigs were at one time unprotected also. Getting good audio reports with an Astatic D104 Minuteman and the original K40 Speech Processor, the RX audio is excellent, reliability is excellent, all at factory spec, 110w pep two tone, 25w AM/FM, if I need more watts I have a big box on the bench, no need to abuse the rig!

  3. tuco says:

    works well now that heat issue/driver mosfet mod has been done. get exellent audio reports with 575m6.

  4. David Shudy says:

    I have been using one for almost 6 years now. Mine has been awesome. I have modded the radio to improve stability and added a pot to extend the echo and added toys years ago and it still kicks a$$. I have the best audio, according to other people and I have used it in competition and won all except for one guy who was running twice as much power as I was and over volted too. I do wish that Cobra would have done better with their volume controls. They wear out too easy. I’m still using the same one but I have had to work on it a few times so far. I have been luckier than most. Roadrunner(aka 133 in dx) in Houston TX wavin a hand. Beep beep.

    • dd182003 says:

      That is excellent, but mine sounds narrow like the modulator does not have enough grunt to drive the audio properly.
      Seems they got the later ones semi fixed.
      What about the display? Mine was hopeless

  5. PD0OYH (Bernard) says:

    Hi. I am a Dutch radio-amateur and happy with the Cobra 200 GTL DX as it is build, as a 10-meter radio. Without mods for CB all the knobs (10 Khz shift) works as it should be. My way to cool down the radio can be found here:
    https://www.facebook.com/media/set/?set=a.134547613264141.38073.100001267090232&type=3&l=303a4bc0a3

  6. indra says:

    Hi dave,
    How much cobra 200 gtl?

    • dd182003 says:

      Not for sale and not a good radio at all I am sorry to say. They did not even try to fix them and removed the cobra 200GTL from the shelves after a few months. The faults on SSB were basic design and unable to be easily rectified so they shelved it..A pity really…it was a great concept and a great price but a dog..not worth the money

  7. jim says:

    love my first 200 1 1/2 years later done sold for parts on eBay now found 2nd one works good on low power put it on hi and power meter moves but no modulation ??? any help please

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