COBRA 200 GTL-DX Technicians have recently been perfecting the NEW Cobra 200 GTL-DX Transceiver.

We now offer a range of approved modifications by the Manufacturer and a number of our own

designed to realise the potential of this 21st Century Transceiver.










There is some confusion by owners between the Six (6) different revisions of 200 GTL-DX chassis 

released by Cobra. We show how to recognise which revision you own and also list our Services.

(Please check this page regulary for updates of new chassis).

With the Top case of the 200 removed, look on the left hand side of the main Printed circuit board

(position arrowed) for the PCB number.


















PLEASE NOTE: By removing the case may void any Warranty on your Transceiver.

Shown below is a Revision 1 PCB number # (PFM-0090A-BA)  SUMMER 2004.









Shown below is a Revision 1 PCB number # (PFM-0090A-BB)








Shown below is a Revision 2 (Late) PCB number # (PFM-0090A-BE)








Shown below is a Revision 3 (NEW) PCB number # (PFM-0090A-BF)








The Six (6) Cobra 200 GTL-DX Chassis start at 0090A-BA through to 0090A-BF (-BA.B.C.D.E.F)

Further visual differences on the PCB are shown below between the 200 chassis REV1 and REV2/3.

The REV1 PCB shown below with Transistor legs through PCB (centre of picture) hole in PCB.



















The REV2 PCB below with the Transistor legs soldered in normal way, no hole cut in chassis.



















Next difference is the output stage devices for REV1 (HF50-12F devices x 2)

note: Some late REV1's used 2SC2290.




















Shown below is the REV2 output stage notice the Toshiba  2SC2290 x 2 devices




















Another visible difference between REV1 and REV2 is the TX/RX switching relay,

REV1 uses HAN KUK HR90 Shown below.

















The REV2 later chassis PFM-0090A-BE uses a SANYOU DSY2Y

TX/RX Switching relay, below.




















The Cobra 200 GTL-DX REV2 was Shipped with Factory switchable Talkback

using the Echo On/Off control. The below picture shows the speaker side bottom cover removed.

The High-Voltage unit with multiple wires in metal box can be clearly seen

attached to the side of the Transceiver (bottom of picture).

















Inside the metal box (seen below) is the Electroluninescent HT (High Voltage) circuit.




















Another view of the NIGHTWATCH High Voltage circuit.






















1: Receiver audio distorted and Transmit audio warble modification

Does your 200 receiver overload when receiving a strong signal, resulting in distorted audio.??

Do you ever get reports of a warble on your modulation when transmitting.??

The latter due to RF bleeding into the front-end.

This mod cures both the Receiver audio distortion and Transmit warble.

2: Frequency Calibration

We correctly adjust the VCO to within Cobra Factory specification.

3: Adjacent Channel NB (Noise Blanker) modification

This superb mod reduces the adjacent channel rejection when the Noise Blanker is switched on,

a must for all REV1's.

4: Echo Delay Speed modification

This modification effects the digital delay to “Speed-up” the echo effect (add reverb).

5: Talkback - Fixed and Variable level modifications available

This mod adds adjustable-volume talkback or fixed-volume talkback.

Talkback allows you to monitor your Transmit audio from the Speaker.

6: Low Audio modification (noise cancelling mics)

The 200 Modulation may be low with some noise canceling microphones.

This mod increases Transmit audio level.

7:Squelch modification

If your Squelch chops in and out or sounds 'feathered' this mod will make the

Squelch threashold more precise. Technicians offer the following modifications for

 Cobra 200 GTL-DX REV2 Transceivers

8: Expand the Clarifier range from 5Khz to 11Khz Swing

Developed for REV2 Transceivers this mod Expands the Clarifier range from 5Khz to 11Khz

giving more 'Swing' to the Clarifier. Technicians offer the following Cobra 200 GTL-DX

REV1 and REV2 Transceivers

9: Unlock the Fine clarifier for RX ONLY!! - same as Cobra 148 GTL-DX

This mod unlocks the 'Fine' clarifier to make it RX receive ONLY, just like the 148 GTL-DX.

This mod transforms SSB operation on the 200 and keeps your Transmit frequency locked when

you tune Stations in using the Fine control. The Coarse control changes Transmit and Receive

frequency as standard.


Please see our Services for latest pricing.

Telephone Cobraworxshopz on;

UK 07508-148-148.