•  Radio and Audio equipment Repairs (since 1985)


  • Restored Cobra 148 GTL DX

    Cobra repair and restoration

    This radio shown above came to us with a damaged case and front bezel , no TX power output, and an intermittant problem of the meter pegging out at full scale deflection while on receive.


    As you can see from the above picture we were able to repair the faults and restore this radio to its former glory

     

    Contact us on

    Phone: 07770  397668

    Text:      07770  397668

    E-mail: np262@yahoo.com

    Address: 8 Pouces Cottages, Spitfire way, Manston, Kent CT12 5BU.


    We welcome customers in Europe, USA, and Australia; if you wish to contact us please phone: +44 7770 397668


    I would like to bring to the attention of our valued customers that due to an unusually high volume of work and the nature of that work I am receiving at this time I still have the intention of achieving a turn-around of radio repairs within 6 weeks, but Radios which have had failed repairs by other poeple, specialist upgrades requiring the designing, manufacture, and construction of custom components for example UK 40 boards, Continuous Tone Coded Squelch System Boards (CTCSS), Roger Bleep Boards, etc. does take a lot longer to install and test; and in the event that we have to source hard to find components for the older radio equipment or communications equipment that has a habit of self destructing when it fails can also lead to significant delays in the repair time of radio or as is becoming more common a complete rebuild if the radio rather than just a repair. 

    If you would like an update on the repair of piece of equipment you have sent to me then please e-mail me at the normal address shown above.


    Marconi Signal Generator

    I have just purchased a Marconi Signal generator, as you can see
    I am just giving it a test on the workbench before moving it to its new home ready to be used.

    It is bigger than I expected, but it will provide additional
    features that we didn't have access to with our previous signal generator.


    Vortex Antennas

     We are please to recommend Vortex Antenna Systems for all of
    your  Antenna needs.


    Magnum Delta Force

    We have an interesting collection of Radio’s this month in for repair, so I have highlighted the Dragon (Magnum) Delta Force, it came in with the normal SSB signal meter Full Scale Deflection  with no signal present, and Weak Transmit Audio on SSB.

    Ham International Jumbo

    Another Radio that we have not seen for a while is Jumbo, it
    arrived with no receive audio on SSB/AM and wouldn’t transmit on all of its channels.

    Galaxy Saturn

    A visitor to our Facebook page commented on the Ham International Jumbo, well I have posted a picture of one of the later replacement radios which I have just finished.  Notice I shown this radio transmitting on FM.  I really like the addition of the Frequency counter so you now have an idea on what frequency it is transmitting.


    President Madison

    I didn’t want everybody to think that I can only repair Cybernet based radio’s, so here is a Uniden based radio I have been working on in the last few weeks.

    President McKinley

    This is another rather good mobile set; this time having the
    same Uniden board as the Stalker 9, but not being a Stalker 9 has the UK40 board mounted on the left hand side of the case.

    President Lincoln

    I have been working hard over the Christmas 2016 holidays,
    with a lot of my ordered components arriving altogether. This is a finished President Lincoln which has had a new PA Output Transistor and Driver Transistor after it was found that the Output Transistor was fake and the other had blown.

    Nato 2000

    I have had lots of fun repairing this set, being one of the only sets other than the Stalker 9 with the UK 40 built in as standard.

    Kenwood TS50

    This second Kenwood TS50s I have seen in the last few years
    in the workshop, when they are working they are a very good example of small mobile Amateur radio HF transceiver.

    Unfortunately by the time that I get to see them they tend to be very much worse for wear; the first one I repaired had 34 separate faults spread across the whole of the radio, fortunately the radio had not been screwdrivered so it was just a matter of finding the failed components and replacing them.

    You have to be aware of fake Chinese components for these radios
    because they just don’t work, and this is an all surface mount radio so unless you're happy with a hot air re-workstation and a fine tipped soldering iron working on these should be left to the professionals. 

    Yaesu FT 767GX

    This is a FT767GX with the 2 meter and 70 centi-meter modulus installed in it; It has taken a few weeks to identify why the ATU was not tuning at all, and the SWR wonder about while it was enabled, and the modules in the back reported to be transmitting 10 Watts but in fact they were only
    producing 1-2 Watts.

    Cobra 148 GTL DX 

    I have had one of the best examples I have ever seen of a
    Cobra 148 GTL DX, which had not been screwdrivered or seriously modified, so I had to photograph it and show you all because this is a once in a life time experience.

    Midland 7001

    You are looking at a rare Midland 7001 multi-mode radio in very good condition sitting on the test bench; it came in with no Tx/Rx, and after a lot of work I am pleased to report that it has come back to life.

    President Lincoln II

    This radio came in with no transmit audio.  It looked like a microphone plug failure had caused the 13.8v supply to go to places it was never intended and the result was the microphone audio signal tracking had gone open-circuit and the microphone dual bilateral switch IC had blown as well. 
    The microphone dual bilateral switch being a small surface mount IC
    great care was taken replacing it on the radios main board.

  • A Full Amateur Radio Licence
    holder who passed with Merit.

    M0NKL

    I would also like to announce that I hold a full Amateur Radio Licence with the callsign M0NKL which I achieved with a merit.



    FT101E restoration and repair

    A picture of me in my workshop working on a FT101 restoration and repair, which is going well.

    Fake 2SC1969 Transistor

    Fake components  

    We have been receiving a number of radios with failed Fake 2SC1969 transistors installed into them; these transistor work intermittently for a short period of time and then failed causing no RF power output.

    If the printing on the transistor is of poor quality then it's going to be a poor quality transistor.

    Fake Components

    We have been receiving a number of radios with failed Fake 2SC2166 transistor installed into them; these transistors work intermittently for a short period of time getting very hot, and then failing causing no RF power output.

    This one had 2.5v across the Base-Emitter junction and still measured correctly when I removed and tested it. If the printing on the transistor is not straight then it's going to be a poor quality fake transistor.

    Fake Components

    I have had the first one of these components arrive at the
    workshop in a non-functioning radio today and I have looked around and they are now appearing on EBay; it appears that the transistor Identification Number is not printed but etched onto the surface of the transistor case.  I am sorry for the out of focus picture but I had lots of problems photographing this component so that you could see the identification number. They have the same problems as all of these Fake components in that
    they produce very little to no power, get very hot very quickly, and then blow short circuit collector to emitter.


    Fake transistors hFE.

    Another indication that your RF transistor is Fake is seen if you measure the Current Gain (hFE), for the 2SC2312 the data sheet states the best current gain is 90-180 with the “DD” ident, but you will normally see the 55-110 ident “CC” with a measured gain around the 90-105 in CB radio sets.

    The Fake 2SC2312 transistor shown above has a current gain of 262 which is just impossible for an RF Power transistor; clearly whatever is inside the package this is not a 2SC2312 transistor.

    Fake Components

    I found this power transistor in a FT 857D in the VHF/UHF power amplifier, unfortunately after repairing the UHF fault the radio only transmitted a few over’s before this fake transistor failed.

    The picture above is a E-Bay seller with a worst Transistor than the one I already have.

    The giveaway is that the printing is heading for the bottom right hand
    corner, is not straight, and the logo and text is smaller than on the original.

    A genuine Mitsubishi transistor is shown below.

    Realistic TRC 44A 

    I thought I would share with you one example of what I have
    been repairing this month which is a Realistic TRC 44A in excellent condition.

    Icom IC740 HF Transceiver

    This radio came in without any transmit output power, it was
    discovered that a number of faults had developed over time, and were successfully repaired after which transmit on all modes was restored.  The normal checks were also performed as well as the On-Air test.

    Noise Cancelling Signal Enhancer
    This is another of the special non radio repairs I have been undertaking this month, an interesting repair with some very difficult to find transistors in it.

    Tokyo Hy-Power HL-45

    I have just changed and re-biased the Power Mosfets in this Tokyo
    Hy-Power RF amplifier, this is the first one I have done as there are not many of these quality products about these days.  The picture shows it transmitting 40 Watts output for 2 Watts of drive.

    CB Radio Spectrum Displays.

    I have been looking at the output of the CB sets I have been
    servicing in the last three months, and have captured some spectrum output displays.

    I have used one of the best Cobra 148 GTL DX Export models I
    have seen in a while, with the only mod being you can turn the power up from the front panel from 0-16Watts.

    The frequency I used for the tests were Channel 19 Mid Band
    27.185 MHz driving a 50 Dummy Load.

    The first image is of FM mode with no modulation with 4
    Watts output, the correct setting for this set.


    I have now used the mod to turn the power up to its full output of 16 Watts, and am really over driving the Final PA stage producing lots of harmonics because of the distortion of the signal which appear as the vertical lines on the display.

    I have to ask myself although my Power meter is showing 16 Watts, where am I producing all of this power, it’s clearly not going into the carrier frequency, but is being transmitted as unwanted signals on the channels either side of channel 19.


    Also notice that the carrier signal has dropped from +10db to
    -10db as well!

    This picture shows the correct power output of 4 Watts FM,
    with the second and third harmonic output being -40db and below.

    Superstar 3900

    This radio came in to have the new UK40 Board fitted and as
    you can see worked perfectly; I also did some routine repair work which came to light when the covers were removed and the radio was tested.


                            Related info

  • A

    1


    What we repair


    2

     

    Amateur Radio repairs.

     

    3

     

    FM and Multi-mode CB repair.

     

    4

     

    Valve & Transistor power RF amplifier repairs.

     

    5

    Audio amplifier repairs.

  • I have been repairing radio equipment since the early 80’s in the days of the PMR conversion of Pye Westminster’s, and CB radio was in its infancy in this country,  I later became interested in Amateur radio, and this lead to my repairing of amateur radio equipment. I specialise in the repair of multimode equipment at component level, with resolving the more difficult problems being what we spend most of our time doing.

    We also do a range of radio programming including the Chinese manufactured range of handhelds and recently Kenwood mobiles.