Grant XL 10 meter mod

[Spud]

Has anyone done the Grant XL 10 meter mod? I believe it's the same for other similar radios.

I found instructions saying to replace crystal X3 with a 11.6908Mhz from the stock 11.325Mhz Couldn't locate a 11.6908 but I did get a 11.6900 which should be close enough.

Swap it out and tested, seems to work except it will only transmit up to channel 13. Channel 14 makes the TX/RX light flicker and anything higher does nothing.

Channel 1 = 28.06 and channel 13 works out to 28.211Mhz but can't get higher. Would like to get access 10 meter voice area 28.3 to 28.5, seems to receive fine.

Does something need to be retuned to allow it to transmit? I was expecting it to transmit on all channels poorly until adjusted, didn't expect it to do nothing at all when keying, stays in RX mode.


Yes, I do have a license to use the band.
Thanks for any help
Dave

 

[ExitThirteen]

Heya Spud!

Welcome to the WWDX forums, hope you enjoy your stay and learn some stuff in the process.


The reason it won't TX above ch 13 is because the VCO is unlocking. L19 is the VCO in this case, you'll have to pull the little dab of wax out of the can, and (gently) retune L19 for full coverage. To get better TX output, you'll also have to retune L45 and L46 slightly as well. Also, remove R95 (1.5k ohm), as this is the range limiter resistor on the PLL.

The 11.6900 crystal will work fine, you might have to retune VR5 if the clarifier is locked to get on frequency. If it's unlocked, then you'll need to adjust L22 for AM, L59 for LSB, and CT2 for USB.

The original 11.325 crystal can also work, you'd just need to pull pin 10 on the PLL chip high (+8V) to get 28.300-28.500. Again, you'd need to retune L19 (VCO) for those frequencies.

Good luck, and have fun.

~Cheers~

 

[Spud]

ExitThirteen,

Thanks! That worked! What a relief.

I turned L19 1/4 of a turn clock wise and now it will TX all the way up to channel 40. I didn't test to see where that ended up yet but should be near 28.5Mhz. I'll look at the other adjustments later, I have to go to work soon and wanted to see if L19 would do the truck before heading off to the salt mine for a full day.

A couple of questions,
I'm testing the frequencies by keying the mic while in USB with the mic gain turned down all the way so that I send out almost no RF and then tuning the signal on a Yaesu to find the frequency it's on.

The signal has sort of a whirly waterfall sound, is this normal? It sounded quieter on LSB but LSB is not used on 10m. I never used SSB on this radio and it has been stored in a closet for years. It did pass through a 'peak n tune' truck stop at some point and they cut out the mod limiter which I put back in but not sure what else they did but turn up VR10&11. I rebiased the final and driver bias using tp8 and 7 with an amp meter, the only problem I had was that the instructions I found said to use VR8 for the final and VR9 for the driver but when I had my meter hooked up the variable pots had the opposite effect, VR8 appeared to adjust the driver and VR9 the final. Adjusted one for 25ma and one for 50ma - I just hope the radio has a clean, clear, and legal signal on 10m.

Second question, do you recommend the clarifier 6khz up down unlock? Each channel is about 10Khz I believe so the unlock would be almost like having a real VFO, can't think of a downside, is there one? The mod sounded like a lot of part clipping, don't want to massacre this radio.

Thanks again for sharing your knowledge

 

[ExitThirteen]

Have you tried to talk on the radio using the Yaesu as a monitor to see how the audio sounds? If not, give that a try and see if the audio sounds clear. You'll only need to run the mic gain about 12-1 o'clock on the grant to get full SSB output. Might want to check TR34 (it's near VR11, the SSB ALC) and make sure it's in place. Some hack shops pull that transistor out also when doing a "peak & tune". I wouldn't worry about the "waterfall" sound much, unless it's interfering with your TX audio directly.

As far as the clarifier unlock goes, I would recommend it, as you'll be needing to get "inbetween" channels (example: 28.420). The crystal you changed should already get you close, but it is nice to tune to someone and have your TX and RX go together. Unlocking the clarifier isn't too bad of a hack job, as long as it's done correctly.

There's a couple mods I'd recommend to help you sound crisper and cleaner on your TX audio. First, I'd locate the audio wire coming off the mic gain control that goes into the PC board, and solder a 330 ohm resistor from the solder pad that wire goes into on the PB board to the PC board ground. This reduces sensitivity of your mic gain control, and clears up the audio tremendously. The other mod I'd recommend is changing C100 (it's a 22uf 6V tantalum capacitor located near the audio wire going into the PC board) to a 10uf 6V tantalum capacitor. This will brighten the audio a bit and provide more audio punch without splatter.

Hope this info helps!

~Cheers~

 

[Spud]

Did some more testing, it's working fine on SSB after I used headphones and dialed it in, sounds about right once I had the receiver on frequency. I soldered in a 2sc945 transistor at Q24 because it was missing, that should prevent overmodulation.

I'm not sure if it's bad or not but I attached both crystals to the board with a toggle switch so that I can switch between 10m and 11m - I'm sure this is illegal but I wanted to see if it would work. Seems to work, frequency drifts a little if I put my hand near the wires. Do you think this is a problem 4 inch leads on the crystal going to a switch, maybe I should pick an Xtal and solder right to board. I played around with the VCO until I could TX on all channels on both crystals. The Receiver seems less sensative than it did before, even on CB which is normally full s3 noise now seems quiet on same antenna.

The power output is low on both bands, about 3.5 watts AM on CB and 2 watts on 10. SSB goes up to about 10 pep on CB and 5w on 10 meter. VR11 and VR10 are turned up about all the way. I'm not sure why the power levels are so low even before I did the X3 crystal mod it was low. Should I adjust coils to improve power?

edit:
I removed switch to change bands and install the 12.69 10M band crystal directly to the board. I rather have one band tuned up well than 2 out of tune bands. Next I'll unlock the clarrifier and work on tuning up the power. I want at least 10 watts pep on SSB. I'm going to make a channel to Mhz chart and tape it to the top of the radio. Looks like 20 and up are in the voice band, 19 and under is in the CW/Data band.

Too bad 10m is so dead most of the time, hopefully this solar cycle brings some fun. I still play on CB sometimes because there is more local activity there. I have a couple of other CBs so I don't mind giving this one up for a QRP/spare 10m fun rig.

I found several instructions for the unlock does this sound right?

If you do the changes below you will get -6kHz to +6kHz with 0 right in the middle. The Tx will track
exactly with the Rx
1. jumper R175
2. jumper D51
3. remove R149
4. remove R188
5. remove R44
6. remove the wire from the high side (+ or full clockwise pos) of the clarifier
7. connect pin3 of IC4 to the high side of the clarifier
8. replace R174 with a 3.3k resistor
9. attach a 12k resistor from the jumper of D51 to pin3 of IC4

Thanks,
Spud

 

[Spud]

Ok it's all done, I hope, working reasonably well except the power is still a little low. I'm measuring 4 to 5 watts AM and about 8 watts pep on SSB, it drops off a little towards the end of the band. Maybe there is something wrong with the finals, I know this radio has been keyed up in the past with a coax short.

I adjusted L45 and L46 just like you said for the power. I did not have a plastic screwdriver so I made one by carefully shaping a toothpick using a sharp knife. This worked great for making adjustments. I used a homemade dummy load, two 100ohm 2watt resistors in parallel. They get hot but for the tuning I kept the mic gain low and fed in a tone from a computer program to give it a constant level. Held the mic next to the speaker, adjusted mic gain for a low power output then tuned it so that the external RF needle as high as it would go.

I did steps 1-7 for the clarifier:
1. jumper R175
2. jumper D51
3. remove R149
4. remove R188
5. remove R44
6. remove the wire from the high side (+ or full clockwise pos) of the clarifier
7. connect pin3 of IC4 to the high side of the clarifier
8. replace R174 with a 3.3k resistor
9. attach a 12k resistor from the jumper of D51 to pin3 of IC4

I didn't do the last two steps. When on channel 28, for example, if I turn the clarifier all the way one direction then go to channel 27 and turn it all the way the other direction they overlap so that I have full tuning coverage. One thing I noticed is that turning the clarifier to the left makes the TX/RX frequency go up in Mhz, and turning it to the right makes it go lower which seems counter intuitive. I did not yet test to make sure the TX and RX frequencies match, I'll do this later but believe they will. A bright desk lamp shining through the PCB will make it easier to find where things are, you can see your hand through the board and put your finger nail on the solder pad you need to heat up. Used needle nose pliers to pull out one end of those resistors and left them standing up in case I want to store the radio someday.

I discovered that IC4 is the voltage regulator bolted to the side of the frame and it's the chip with 8 pins closest to the front, pin 3 is the 6th pin from the front of the radio with 2 more heading towards the rear of the radio. Hope this helps someone because I had trouble finding exactly which one it was. I also cut the white wire on the clarifier, some of the instructions I found said to cut the orange one and some said the white. I went with the white one which is the 'fully clockwise' side.

Using the 11.69Mhz crystal for X3 this is the range of the radio
Channel 1 = 28.06Mhz
Channel 6 = 28.12 = PSK31 area of activity
Channel 21 = 28.301 - First safe to use voice area, Channel 20 is half in the voice range depending on clarifier position. Play it safe and stay 21 or higher
Channel 28 = 28.385Mhz - QRP SSB Calling fequency with clarifier at the 9AM position
Channel 40 = 28.500Mhz - Easy to go over this with the clarrifier - if you're not a General class or higher don't use channel 40.

Thanks a bunch the help! I hope my notes here help someone in the future with their radio.

Time to play on 10 meters

 

[ExitThirteen]

Well, if you're looking for a couple extra watts on TX, and "open" up the TX range a bit, I have a couple mods you can do.

Locate C163, which is snugged up right next to L45. It's a 2pf ceramic disc capacitor. Replace C163 with a 5pf disc capacitor. Next thing to do is locate IC5, which is a 14 pin DIP IC labelled S042P. To the right of it there's a 100 ohm resistor marked R190. Jumper this resistor on the foil side of the PC board. Last, on the S042P IC, (I'll try to explain the best I can) locate the traces that you jumper across R190, and solder a jumper from either trace to the PC board ground. (In essense, you're grounding out the 2 pins on the IC that are connected to R190.) This IC is the TX mixer IC, and grounding out those 2 pins amplifies the TX mixer stage to its full potential.

Also, you'll want to adjust L38, which is an inductor with a slug in it, for maximum SSB output. Since you can use your computer to generate a tone for SSB, that will work fine.


To run both CB band AND 10 meter band, I'd highly recommend that you reinstall the 11.325 mhz crystal, and simply wire a switch from pin 10 of the PLL chip to a stable +8V source (you can find +8V at the + side of C84, which is right next to the PLL chip on the left). This toggle will allow you to have both CB and 10 meter bands on one switch, with no need to switch out crystals, which are very sensitive to moving frequency when using long leads, since low level RF pass through the crystals.

Hope this info gets you going!

~Cheers~

 

[Spud]

Good suggestions, I'll try doing those after I do some on air testing of the radio to make sure it sounds good. I saved the original crystal by hot gluing it to the inside of the radio so that it never gets lost.

I could hear people on two frequencies with the Yaesu, they were weak, one didn't move the signal meter at all and the other went to about S4 but I could understand them perfectly. When I tried to tune them in on the grant I heard nothing at all. Does the RX need to be realigned similar to how the TX portion was?

I don't have a RF signal generator, two things I thought of was to wait until I could hear a CW automated beacon when the band opens up or transmit the weakest signal I can with another radio, adjust the RF gain on the Grant to put the signal about midway on the internal S meter then tune the RX coils to make the needle go higher. I believe I need to adjust L4, L5, and L6, they are listed in the SSB RX alignment section of this page The Defpom Grant XL (PB-208AA) alignment page

Is that something you recommend or does that sound like something I shouldn't need to do? I'm going to mark the exact position of the coils and record adjustments so that I can undo them if needed.

Edit
I turned L6 clockwise 1/16th of a turn, L5 half a turn clockwise, and L4 in a full turn clockwise. This increased the amount of my own test signal I picked up and raised background noise a little.

I noticed my clarifier only affects TX and not RX which might be why I can't tune in anyone.

Update:
I reconnect the white wire to the clarifer and my RX clarifier started working again. I clipped the yellow wire and then connected that to the IC4 pin 3 and now it's good. The clarifier is the same on RX and TX and moves about 10khz on each side. The last two steps must narrow the range which is too wide. The best news is now the clarifier turns the right way too - turning it clockwise goes up in frequency and turning it to the left goes down the band.

 

[winstar]

Hola All!

i have a PRESIDENT GRANT and i am a OM...
can i convert my grant in 10meters radio?
28.000MHz to 29.700MHz (30.000MHz) ?
can we help me please?

thanks!

 

[9C1Driver]

Hola All!

i have a PRESIDENT GRANT and i am a OM...
can i convert my grant in 10meters radio?
28.000MHz to 29.700MHz (30.000MHz) ?
can we help me please?

thanks!

Welcome to the forum.

You might try starting a new thread on this topic rather then try to high-jack this thread, you will get more views and reply's that way.

That said the President Grant is already a 10m Export radio, it should already have 10m.



http://www.cbtricks.com/radios/president/index.htm

 

[9C1Driver]

As far as the Grant xl in this thread, I would just do the channel mod off the chip and let the radio be what it is supposed to be. If you have a ham ticket and want to talk 10m buy a ham rig. Just hate to see a fine Grant xl get all twisted around, no wonder it only does 5-8 watts. The finals are fine, your trying to make the radio do something is it was never intended to do. My nickle worth.

 

[Once Bitten]

high-jack this thread

That's kinda like hi-jacking the plane after it has landed.

 

[winstar]

73 to ALL!
are in possession of amateur radio license,
but I have no money available, so for the moment I wanted to change my PRESIDENT GRANT in a 10m transceiver.

today I disassembled and saw that the motherboard is marked UNIDEN Model PC-409AC
who can help me?
tnx!

 

[winstar]

UP =)

 

[Spud]

It has been a little over a year since I converted the grantxl to 10M and it was fun but never worked very well.

I recently switched it back to regular CB. Put back the original crystal, undid the unlocked clarifier, and realigned it. I'm having a problem with the RX/TX SSB frequencies aren't the same but I'll get that sorted out as soon as I get my hands on a frequency counter. Goal is to get it back to like new.

The power out was always kind of low on 10 and it would start to distort the SSB if I tried to push it more than a few watts. I'm not sure why that was and never managed to fix it but it didn't matter, the back of the radio ran hot enough for me at reduced power. I did feed a tone into it while transmitting into a dummy load and adjusted all the TX coils for maximum output but still never equaled what it did on 11m.

Used it for PSK31 and JT65, made contacts with Argentina, Uruguay, Brazil, Puerto Rico, Portugal, UK, and the Ukraine.

So it worked but not very well. I think you'd be better off leaving such a fine CB radio as a CB radio and buying a single band used 10 meter radioshack rig off fleabay if money is tight. I've seen them going for about $100 give or take all day long.

Switching it over was just a personal challenge to see if I could do it and it had already been hacked up a little, someone had pulled out the modulation limiter before I got it(I reinstalled the limiter). The latest radio toying around has been QRP kits and wire antennas.