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Cobra 148 gtl dx 11 meters to 10 meters conversion

Discussion in 'Radio Circuits, Repair & Performance' started by M0MTS, Jun 5, 2007.

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  1. M0MTS

    M0MTS Ham Member QRZ Page

    I have an old cobra 148 gtl dx,which i would like to convert to 10 meters (I am now a full license holder) :
  2. W4GLM

    W4GLM Ham Member QRZ Page

  3. M0MTS

    M0MTS Ham Member QRZ Page

    Hi Mac
    thanks for your help,is the 148gtl the same as my 148 gtl dx,I`m not sure.Only got it out of the loft the other day,not been used for years.It has the PB010 chasis.and an If Frequency of 10.695
  4. W4GLM

    W4GLM Ham Member QRZ Page

    Cant really speak to the 148GTLDX.

    I do know the 148GTL was made for the US market and

    was only a legal 40 channel unit. very easy to move to 10

    meters. After conversion, you may need to align the recv.\

    But will probably work just fine, especially as the band


    G.L. with the mod.....Mac
  5. AB8RU

    AB8RU Ham Member QRZ Page

    Banks of 10 & 37 Mhz. Oscillator XTALS with one not in sequence that was RC channels.

    grab a calc key is 37 Mhz. the RCI was set up with alot of Synth. XTALS for 10M.

    also FREQ Counter , and signal generators are sugguested to tune up and a Schematic or a SAMS Photofact Manual.

    BTW also a dummy load.
  6. N1JBS

    N1JBS Ham Member QRZ Page

    Seeing that this is a little old..... Since when does a PLL radio use banks of 37 mhz xtals?

    The loop xtal you want to change is 11.3258mhz
    I have started a page on my freewebs site on cb to 10 meter conversions:

    The cobra 148 gtl dx does not use the same mixing as the regular 148 gtl.
  7. WA7KKP

    WA7KKP Ham Member QRZ Page

    [​IMG]? Are you thinking this is an older 23 channel crystalplexer?

    This radio is a synthesized -- and easily modified for out-of-band operation, per the other posts.

    That is why they are quite popular in the CB world, being a 15+ year old design.

    Gary WA7KKP
  8. KD6NIG

    KD6NIG Ham Member QRZ Page

    You could go on ebay, overprice it, get some sucker to buy it, and get another radio too [​IMG]

  9. GW0VCK

    GW0VCK Ham Member QRZ Page

    The PB010 version uses 15.000mhz Xtal (soldered to the 3 tuning coils at the front end of the set, below the 10.695 xtal), in some cases it might use the 15.450mhz Xtal (but very rare), Just calculate (by adding .450) for the next Xtal upwards to get you into the 10mtr band.

    For eg: if your set uses the 15.000mhz add .450 + .450 which will give you obviously 15.900mhz, The set then should start on "low band" will be 27.865 - 28.305 upwards, if your set has already had the diode matrix mod done to it then it will go right up into 10 but you WILL need to relock the VCO and retune RX&TX stages too, Where you can get Xtals from i don't know.

    It would also be a good idea to retune freq with coarse in centre position to .000 rather than .005

    Hope this helps.
  10. W7CMG

    W7CMG Ham Member QRZ Page

    What is a "full license holder"?  
    What country is that callsign from? (just curious - no info on QRZ)
  11. PA5COR

    PA5COR Ham Member QRZ Page

    Looks like an new UK callsign, Full license means the same here as the extra over @ your side of the pond, fully licensed without CW exam taken since it was abolished.


  12. K7KBN

    K7KBN Ham Member QRZ Page

    If you're going to be working DX when the bands finally open up, you should be familiar with THIS.

    If you use the ARRL log book, you'll find this information 3 or 4 pages from the back.

    You can find any number of web pages with the same information, and probably easier to use. This was one of the first ones I found using my friend, Mr. Google.
  13. KI4TCB

    KI4TCB Guest

    best to just sell the 148 on ebay and pick up a good shape to brand new HTX-10 for peanuts! i paid new in the box for one for only 61 bucks!! on ebay! and i love it for a nice 10 meter HF mobil. remember that radio shacks HF's are made by uniden so they are not to shabby at all. in do time try to look on this sight for a nice HF made by the top three or on ebay and
  14. AI3V

    AI3V Ham Member QRZ Page


    Hi, Converted the same radio the other way,from 10 back to 11

    (pauses to don flameproof tighty-whities)

    Very straight forward, Only one xtal to swap,bought mine from jan crystals. only problem was there seem to be about 3billion minor variations of the pcb,I had to piece together 2 or three different schematics.  and eserviceinfo  were helpful

    The radio will make 12w pep ssb and 4w am, dispite what the cb shop says.

    was easy to make the tx clarifier follow the rx ,all my attempts to increase the range more than about +-500hz
    were unsatisfactory,never could get a nice tuning range.

    Radio will need to be realigned  thru-out ,again a straightforward job,lots of info out there, IIRC mine was well under .5uv rx

    Its a real nice radio, and you will be happy with the conversion, Good soldering!

    73 Rege/AI3V

    Edit: I used the following equipment for the alignment
    Dummy load
    frequency counter(optoelectronics 2600?)
    signal generator (an/URM-25)
    20 mhz o-scope

    nothing fancy,allmost anything you can get will work
  15. EI3GAB

    EI3GAB Ham Member QRZ Page

    Callsign is a UK foundation license, its a kind of CB license that introduces newbie's to Experimenter/Ham radio I think?

    I would assume he means he has now passed the other examinations when he says "I'm now a full license holder" and this is why he wishes to convert his cb as with his introduction callsign he would not have had the privileges to use 10m.
  16. 2W0ZAE

    2W0ZAE Ham Member QRZ Page

    The foundation licence has nothing to do with CB,its the first grade licence in the UK Amateur radio structure.And you do have to do a introduction test on morse and pass a exam to get licence very similar to the USA Tech.The next step is a intermediate licence and lets you make homebrew,and lets you use more power 50watts.Then when you pass that, you can go for the final full licence.And foundation licence holders can use the HF,VHF,UHF in the allotted UK band plans but power is restricted to 10 watts.
  17. KC9GUZ

    KC9GUZ QRZ Member

    The 148GTL has been around since about 1978 or so. its a dated design but it works and works well. I had a 148 GTL a few years ago and i wish i still had it. Yes, i DO still get on 11 meters now and then, Hi.
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