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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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20th Jan 2020, 6:53 pm | #1 |
Triode
Join Date: Dec 2019
Location: Pontefract, West Yorkshire, UK.
Posts: 16
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JRC JST-135 Vfo knob removal
Hi
I am taking off the front to change some of the tact switches on my JST-135, does anyone know the hex key size for the VFO knob, 1.5mm seems a loose fit and I wouldn't have thought it was 1/16, don't want to risk breaking it. |
20th Jan 2020, 9:04 pm | #2 |
Heptode
Join Date: Jan 2008
Location: Birchington Kent, UK.
Posts: 596
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Re: JRC JST-135 Vfo knob removal
Hello Dave
I don't have the definitive answer, but: Kenwood TS830 = 2mm Kenwood R5000 = 1.5mm just as a point of reference!
__________________
Regards Pete |
20th Jan 2020, 11:01 pm | #3 |
Triode
Join Date: Dec 2019
Location: Pontefract, West Yorkshire, UK.
Posts: 16
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Re: JRC JST-135 Vfo knob removal
1.5 feels sloppy as though it's going to damage the key or the grub screw, if the grub gets damaged it's trouble! Will get a 1/16 which is 1.588mm, 2mm is to big
Thanks Dave G4OSY |
21st Jan 2020, 1:17 am | #4 |
Triode
Join Date: Jul 2008
Location: Echuca, Australia.
Posts: 28
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Re: JRC JST-135 Vfo knob removal
HI the hex key you need 1.45 mm or 57.5 thou . A very odd size but I just checked the one on my nrd525 knob .all the best JON VK2FSW PS a 1.5 mm may fit but seems very tight
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21st Jan 2020, 6:56 am | #5 |
Hexode
Join Date: Apr 2017
Location: Buderim, Queensland, Australia.
Posts: 428
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Re: JRC JST-135 Vfo knob removal
Hi there,
I just checked, and my JRC NRD515, an earlier receiver, has knobs with 2.00mm AF "allen type" grubscrews. Imperial 5/64 inch also "feels" correct size, but I am sure that my knobs would be 2.00mm ex factory. This would correlate with your finding that 1.5mm AF is 'loose". May not be applicable to your knobs, so double check. Very good luck to you. |
21st Jan 2020, 6:42 pm | #6 |
Triode
Join Date: Dec 2019
Location: Pontefract, West Yorkshire, UK.
Posts: 16
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Re: JRC JST-135 Vfo knob removal
Thanks everyone, I got it off! A 1/16" 1.588mm fitted perfectly but it still wouldn't budge! So I used a piece of 10 gauge wire put it into the hole and the hex key head, I then heated the wire with a soldering iron being careful not to catch the plastic, heat conducting down to the grub did the trick, JRC must have used various size grub screws during production, got the pcb off now to change the faulty tact switches, BTW its a fantastic rig, superb receiver, has the 240hz filter which is too narrow looking for a 500hz, read some were you can use Kenwood or Icom, can anyone confirm?
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21st Jan 2020, 9:15 pm | #7 | |
Heptode
Join Date: Jan 2008
Location: Birchington Kent, UK.
Posts: 596
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Re: JRC JST-135 Vfo knob removal
Quote:
Shown is the underside of a Kenwood filter.
__________________
Regards Pete |
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21st Jan 2020, 10:49 pm | #8 |
Triode
Join Date: Dec 2019
Location: Pontefract, West Yorkshire, UK.
Posts: 16
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Re: JRC JST-135 Vfo knob removal
Yes Pete thanks, the JRC is in line & 2 threaded studs, it's the Icom I think fits but the grounds are soldered the FL52A somewhere I've seen it mentioned online, not sure on the impedance though, probably better of waiting for a JRC one to pop up on ebay.
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