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Message |
    
Wd259
New member
Username: Wd259
Post Number: 5
Registered: 10-2006
| | Posted on Wednesday, November 29, 2006 - 6:05 pm: | 
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Hi all,
Hope everyone had a good Thanksgiving.
I have a Grant XL my wife got at a auction some time back. Pretty clean and "sorta" works. It looks like its very close to my Cobra 148 Chassis.
Heres my issue, it appears to have a expo kit on it (Pot with 3 crystals). The channels work if you fiddle with it a little but drops in and out. I'm thinking its the VCO osc or something like that out of alignment . I dont have any info on this rig at all and I would like to get her in shape again if I can.
Does anyone have any suggestions on getting her stable again (Radio ..not the wife..no hope there). Where's the VCO pot...? Does it require a broad band mod?
Any info, suggestions or other mods are as always appreciated.
Thanks all, Dave |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2322
Registered: 9-2004
| | Posted on Wednesday, November 29, 2006 - 7:00 pm: |
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VCO is L19.
input of DC voltmeter to TP9
radio set on ch. 40am
adjust L19 for 3.20 volts. check channel 1 for 2.45 volts.
make sure you use the right plastic tool. a jewelers screwdriver will be useless as it will distort the readings.
anywhere from 3.2 to 3.3 volts should be fine.
i would get rid of the EXPO kit. they do not tend to work well on SSB, and thats usually what the extra channels are for.
find the crystal labled 11.325 or 11.3258 and solder it back onto the board where the two wires from the expo kit are currently attatched.
then realign the VCO.
some contact cleaner on all the pots and channel changer couldnt hurt either. (do not use WD40)
here is a link to a full alignment of that chassis, its acually for a 148/2000gtl but they are the same.
might be one trimmer cap used in the grant XL that is a tuning coil in the 148/2000 version.
everything else should match right up.
good luck, first thing to do is to go to radio shack and get their TV alignment too set.
http://www.copperelectronics.com/cgi-bin/discus4/show.cgi?tpc=34&post=113535#POST113535
matt
PS- if you really want to keep the expo kit; reheat all the solder joints to make sure they are good,clean the switch with contact cleaner, and you can cut R95 right by the PLL to broadband the VCO. may have to realign VCO coil after removing R95. |
Wd259
New member
Username: Wd259
Post Number: 6
Registered: 10-2006
| | Posted on Wednesday, November 29, 2006 - 8:58 pm: |
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Thanks much KidV,
Im a aircraft avonics electronics tech so I have all the tools. I call the alignement tools "diddle sticks" (showing my age maybe). Have most everything on the bench but a freq counter. Working on that. I run mostly all SSB on 27.475 to 785. All the mods I saw were lacking in the freqs I really wanted.. so I guess I'll reflow the solder jounts on the kit, tweak the vco and and clean her up, maybe get lucky. I use ContaxHP cleaner on avonics and I'm sure it will work fine here, no residue and alcohol based. Dumb question as far as test points and board layout, is it shoot and pick or is there a layout somewhere I can use?
Well done on the tips by the way, I give you a A+ in tech writing  A++ In kindness
Thanks again and let me know if I can repay the favor, pretty good at mosfet and transister stuff generally. Used to play with the old tube rigs way back and just out of practice on cmos & solid state stuff, getting there. Running a old Kenwood TS-950D on the base, having a blast.
Take care & 73, Dave |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1420
Registered: 6-2004
| | Posted on Wednesday, November 29, 2006 - 9:13 pm: |
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It sounds like the crystal switch - not pot - is dirty and isn't making contact sometimes. Clean the switch before you try anything else. Especially before you start adjusting the VCO. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2328
Registered: 9-2004
| | Posted on Wednesday, November 29, 2006 - 11:58 pm: |
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good deal dave,
thanks for the flowers!
im pretty sure that the TP numbers are marked on the PC board, but not sure on the grant XL.
as for a layout, the service manual is available on line im pretty sure.
welcome to the forum, im sure you will like it here. if you want to try a really cool mod for your grant, do a google search for: "the mod" or "the_mod".
good luck,
matt |
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