The COBRA TRANSCEIVER MKV (MK5)
was not a Cobra Factory production model.
The COBRA TRANSCEIVER MKV was instead a
Literally years ahead of any 10/11 meter radio of it's Genre.
The Transceiver MKV was crafted into creation by a
true Genius of our time called,
Mr. John Nugent
(Amateur Radio Callsign G1LFY.)
John traded under the Business name
JENTEC was an acronym for "John E. Nugent TEChnology".
John lived in a town called Plaistow,
located in the east part of London, England.
John made only +/- 280?* MKV's and today they are VERY rare
and good examples almost impossible to find.
The Cobra TRANSCEIVER MKV started out life as a MKII Cobra 148GTL-DX PB010AA/AB chassis.
The Cobra 148 GTL-DX had the PLL stage components removed from the main PB010 PCB. The Channel Selector complete with Channel Indicator LEDs and TX/RX LED were removed.
The Channel Indicator LEDs location on the front panel was expanded to house the MKV Frequency Counter PCB see below.
John then designed a 5-Digit Frequency Counter and TX/RX LED PCB and furnished it with a Digital Incremental Encoder for the Channel Selector that has an unrivalled performance and unique feel make it a pleasure to operate. The Digital Incremental Encoder has a very smooth feel to each turn of the control. Unlike the standard 148 Channel Selector with 40 positions the MKV Encoder has 50 thus expanding the tuning range by 25%.
John's pure Genius was in designing the
Jentec Cobscan Conversion Board, which essentially
made the MKV unique from any other Transceiver.
Fully-Digital, several different versions of the
Conversion Board were produced by John Nugent,
each PCB was an improvement on the previous version.
The below JENTEC COBSCAN PCB was actually the first design
and was fitted only in the 1989 released
Cobra Transceiver MKIV (MK4).
Notice the 4Mhz Microprocessor and row of ten variable potentiometers used for alignment.
The next Version of the JENTEC COBSCAN PCB is shown below.
John called this the MKIV 060489 (MK4) dated 6th April 1989, updated now with an 8Mhz Microprocessor. John also called his Software written into the Microprocessor the "SCAN " Series. Several versions of SCAN software were released. The below Processor was programmed with the SCAN 58 Software on the 28th Febuary 1991.
So far, as of 18th June 2011, Cobraworxshopz have identified Six (x6) different JENTEC MKV Mother Boards designed and built by John Nugent. John made the final PCB design shown below, this is the JENTEC COBSCAN 060393 MKV Mother Board dated 6th March 1993. This PCB utillised surface mount components SMT, has double-sided print and was a third smaller than the previous designs. The below Processor was programmed on the 10th February 1996 and was sadly one of the last, if not the very last MKV's made by John Nugent.
JENTEC MKV COBSCAN PCB solder-side below.
FIRST JENTEC COBSCAN MKV
RARE 6-DIGIT VERSION
SCAN 38 SOFTWARE
MKV COBSCAN REV
Shown below is a picture from the solder "print-side" of an early JENTEC COBSCAN MKV Motherboard. The original design was dated 15th September 1989 and refers to the first very rare 6-Digit Frequency Counter MKV version (SCAN 38) with "SPAN". The board was then designed around the more common 5-Digit Frequency Counter version and dated 22nd March 1991.
Almost one year later, John designed a new JENTEC COBSCAN MKV board, different components were used and the PCB was smaller than the previous revision. The board below shows that original date as 16th March 1989 and the latest revision for this board is dated the
6th March 1992 (see below).
Exactly one year later, John made what was to be the latest and sadly final JENTEC COBSCAN MKV Motherboard. The below picture was taken from the MKV made in 1996 and shows the inception date as 16th March 1989, with this revision being designed on the 6th March 1993. The 1993 JENTEC Motherboard was the smallest so far and utillised a double-sided printed circuit board, updated components and a different circuit design. The PCB was about one third smaller than the original 1989 pcb.
SCAN SERIES SOFTWARE
The dates and numbers written on the Microprocessors were by John Nugent himself. Inside the MKV John also attached an individual Serial number to the Transceivers cases that he modified. The dates and information on the Microprocessors show the development, over time, of the SCAN Series Software. We have identified several revisions of the SCAN software (11 in total, not all shown here). The first MKV SCAN Series was the "SCAN 38" used in the 6-Digit Frequency counter revision made in 1989. The below 4Mhz Microprocessor is utilising the SCAN 52 version of the software dated
11 October 1990.
In only 4 months (October 1990 to Febuary 1991) John had developed the SCAN 52 software into the SCAN 58 revision and upgraded from a 4Mhz Microprocesor to an 8Mhz Processor. See above & below pics.
SCAN 165 SERIES SOFTWARE
John produced the SCAN 165 Series Software a few months later see the below EPROM dated 31st May 1991.
SCAN 175 SERIES SOFTWARE
By early 1992 John had developed the SCAN 175 version of MKV EPROM programming code. Various bug fixes were published in this release, the below pictures show Eproms dated 14th January 1992 and 10th February 1992, containing SCAN 175 MKV software.
SCAN 194 SERIES SOFTWARE
By the middle of 1992 John had developed the SCAN 194 Software shown on the below processor.
SCAN SERIES SOFTWARE 1994
Cobraworxshopz have not seen much in the way of MKV processors programmed during 1993, although John made a newer version of the pcb dated 6th September 1993. The below processor numbered #268 was programmed in February 1994 and was installed into a 060993 JENTEC Mother Board.
LAST SCAN VERSION AND PROCESSOR
The last MKV made by John that Cobraworxshopz have seen is the radio shown and featured on this webpage (currently owned by a Transceiver collector from the West Midlands in England). A picture of the processor from this radio is shown below and dated 10th February 1996. This was less than one year before John sadly departed this world.
JENTEC INTEL HEX DATA
The Holy-Grail of the JENTEC TRANSCEIVER MKV is the
SCAN Series Software. The SCAN Series was
developed and improved with later revisions as time passed,
allowing the Processor to control all the complex tasks
associated with the MKV. Below is a screen shot of the actual
HEX data from a SCAN 58 Eprom.
JENTEC I.F. PRE-AMP
A small number of JENTEC MKV Transceivers we have serviced and repaired over the years were fitted with an extra I.F. Stage, designed and built by John Nugent (see below).
The pcb was made on Veroboard and consisted
of a small number of components.
The pcb has just 3-wires that were used to install the board into the I.F stage of the PB-010 Chassis.
The effects and results of the JENTEC I.F. PRE-AMP are quite impressive, normally on a Cobra 148GTL-DX a 1-micro-volt applied RF signal to the receiver, will typically generate a zero signal strength reading on the S/RF meter, with the received
carrier on FM being rather "back-of the box" but still audible
with some smooth noise.
The addition of the I.F stage gives a boost to around Signal 5 on the S/RF meter and the FM carrier is now noise free.
The effects on SSB are very similar but make the S/RF meter much more lively and responsive.
The Chrome Bezel from the original 148 was used and John created a new Transceiver MK4/5 Face Plate and modified the Channel Indicator LED space on the Bezel to incorporate a 5-Digit Frequency Counter with Diffuser in GREEN or RED.
(see above/below pictures).
The Cobra Transceiver MK5 boasted a host of features, many unavailable to any 10/11 meter Transceiver at the time.
Here is the full list of features:
26-30Mhz using 4 position Band Switch
1Kc RX/TX Clarifier
Scan Facility, UP/Down,
(could stop on a busy channel if using squelch)
Timed Scan resume
Astatic Teardrop with UP/Down buttons could
Scan/Change Frequency UP/Down
10Kc - 1Kc channel steps
+/- 100Kc Repeater offset
S/RF and Power S-Meter indication
5-Digit Frequency Counter (Red or Green)
Big Heatsink on rear panel
Zero-40 watts AM/FM variable
Zero-40 watts SSB
PB010 Cobra Chassis
John Nugent tragically died early in 1997,
his contribution to CB/Amateur Radio has been incalculable.
*Interestingly, John only modified 148's sent to him personally. John didn't buy 280* MK2 148's and mod them, counter to popular belief. Only operators/148 owners who knew of John and how to contact him, as he did not advertise, were the lucky few who owned a MKV purely by word of mouth. John later sold MKV
"JENTEC COBSCAN Kits" so you could 'make your own MKV'.
Recently Cobraworxshopz have heard it suggested that the different colours of MKV Frequency Counter LED's (Red & Green) were significant and showed if the MKV was
made by John or was the 'build your own' Kit version.
Another suggestion that made us here all laugh out loud, is that Cobraworxshopz infact made the Green Version and also a recent COB-P1 that was for sale on eBay.
Typically none of the above Urban Myths are true in anyway,
just nonsense made up by the usual attention seekers
(you know who you are).
Straight facts are the Green LED versions were designed around a different type of 7-segment LED display (SIEMENS HD1077G) and the digits were physically smaller than most Red versions*
(VISHAY TELEFUNKEN TDSR1160) hence a different JENTEC Frequency Counter PCB was used on the Green MKV's,
all constructed by John Nugent.
*note (some Red MKV's were also supplied in the small digit sizes)
Please see the below price list from Mr John "Jentec" Nugent from 1993 / 1994 to see a small selection of the conversions John produced. Interestingly John was more famous here in the London area for his Amateur Radio "PACKET RADIO MODEMS"
As can be seen from the above price list, John modified various radios, including, Cobra & Superstar (MK1 & MK2), Cybernet 134, Uniden, Audioline, Cybernet, Tristar, Jumbo, 777 etc, Stalker 9, Stalker 9 DX etc. So next time a "Rotel RVC240" appears on eBay, don't be too suprised if it has a JENTEC conversion board installed.
Cobraworxshopz.com Technicians have Mastered the
"JENTEC COBSCAN" Transceivers made by John. We pride ourselves in having the MKV "BluePrinted" and with most parts in stock, we can repair, maintain and service the MKV completely.
MKV JENTEC SERIAL NUMBERS
All Cobra Transceiver MKV's had a small white sticker attached to the speaker side of the case with a serial number and date,
hand written by John.
MKV ANTI-TAMPER SEALS
In an attempt to stop "Screwdriver-Experts" 'improving' the MKV, John added some ANTI-TAMPER Seals to the Transceiver cases.
The Seals were made of a white-coloured circular sticker placed on either side of the cases. The Seals were similar to a kind of paint and would easily break if Tampered with as seen below.
Cobraworxshopz.com Technicians offer several Special Mods ONLY available for the MK4/5 Transceivers.
We also have the Full Cobra Transceiver MKV operating manual and technical guide, written by John Nugent himself,
a must for any owner or Radio collector,
avaliable to purchase from Cobraworxshopz.
Please call or email us to get yourself a copy.
Cobraworxshopz.com are often asked
three questions regarding the MKV.
Firstly do we have any for sale, secondly can we 'make' a MKV and thirdly how much money are they worth???
We do on occasions have MKV's for sale, not our own but customers MKV's who are willing to part with their highly sought after Transceiver. These will be advertised on our website under the 'For Sale' tab or in our Ebay shop.
Transforming a COBRA 148 GTL-DX into a COBSCAN TRANSCEIVER MKV is an incredibly time intensive operation and takes many, many hours and requires multiple engineering and electronic skills to complete the conversion. Unfortunately Cobra Transceiver MKV's are not a financially viable product to produce today because of the sheer amount of time involved in the conversion process, hence Cobraworxshopz.com does not currently offer full conversions.
The price today of a Cobscan Transceiver MKV varies greatly depending on it's general condition and functionality. MKV's with faults in non-working states generally fetch £200 or $375 on eBay and
100% working condition MKV's presented in original condition
£600+ or $1100+
Of the 280 MKV's John Nugent converted
how many still remain out there?
Click on the picture below to see a working Cobra MKV
Please contact Cobraworxshopz.com for all Cobra Transceiver MKV Repairs, Spare Parts and Mods.
Telephone UK on +44 (0) 7508-148-148
"THIS MAY BE OF SOME HELP, John"
This page is an on-going work in progress and as such will be updated at any time.
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