Grant XL alignment and Freq Counter question

[Lkaskel]

Hi Everyone,
So I am aligning a Grant XL (PB-208AD). I just got my replacement freq counter (HP 5335A) from the alignment shop and it seems like it is working perfectly. I have aligned a radio and it went well. I am now on to the Grant XL and hmmm. In the frequency alignment process I am supposed to connect the freq counter to TP-5 and align USB to 7.8015 and LSB to 7.7985 +/- 5Hz. The freq counter is not locking onto a stable reading for me to align it. It sees 7.*** but its not a sable reading. I feel like it is just below the input sensitivity level of the counter. Have you experienced this? Is there a way around this? I am thinking I may need a small input amp to help this out in the future.

Thanks!!

 

[loosecannon]

you are correct, it's just a very very low level signal there, and can be hard for counters to lock on to.

I actually have a Protek counter whose entire purpose is aligning the IF on the SSB uniden chassis since it seems to be able to grab them.

you can get one of these:


for about 20 bucks on ebay that will amplify the signal enough to read it, or you can use another popular method.


you'll need an accurate 1000hz tone generator of some sort. you should be able to use your counter to set it right at 1000hz.

now make sure you have the PLL portion aligned (the 34mhz coils).
put the radio in SSB mode, and pull the wires from TP7 and TP8 so that the radio isn't providing any power to the driver or final.

now connect the antenna jack of the radio right to the counter (if you have a sample port you don't need to disconnect the TPs and can run right into your dummy load and just sample the freq.)

with the mic gain up, key the radio and inject your 1K tone into the mic on LSB channel 20.

you should read 27.204000 on the counter and can adjust the LSB coil until you do.
for USB it's 27.206000.
as long as your 1K tone is accurate, so will your output freq be.


now, all that being said, trying to align those SSB If coils for perfectly on frequency isnt really the way to do it even if the service manual says so.

we don't know the actual curve of the filters in your particular radio, and if they are off, being right on freq with the IF coil still won't be where the radio sounds best on SSB.

You need a good bench radio that has been confirmed to sound excellent on SSB with the clarifier centered. ham radios are good for this.

now once you get the IF coils close with the previous method, go back and tweak them slightly while listening to yourself on the good bench radio.

you'll find that too far one way sounds tinny and too far the other way sounds bassy.
just align them so the radio sounds good on SSB TX and you're all set.

i find this to work better than trying to just set them for the right freq.
LC

 

[Lkaskel]

you are correct, it's just a very very low level signal there, and can be hard for counters to lock on to.

I actually have a Protek counter whose entire purpose is aligning the IF on the SSB uniden chassis since it seems to be able to grab them.

you can get one of these:
View attachment 49478

for about 20 bucks on ebay that will amplify the signal enough to read it, or you can use another popular method.


you'll need an accurate 1000hz tone generator of some sort. you should be able to use your counter to set it right at 1000hz.

now make sure you have the PLL portion aligned (the 34mhz coils).
put the radio in SSB mode, and pull the wires from TP7 and TP8 so that the radio isn't providing any power to the driver or final.

now connect the antenna jack of the radio right to the counter (if you have a sample port you don't need to disconnect the TPs and can run right into your dummy load and just sample the freq.)

with the mic gain up, key the radio and inject your 1K tone into the mic on LSB channel 20.

you should read 27.204000 on the counter and can adjust the LSB coil until you do.
for USB it's 27.206000.
as long as your 1K tone is accurate, so will your output freq be.


now, all that being said, trying to align those SSB If coils for perfectly on frequency isnt really the way to do it even if the service manual says so.

we don't know the actual curve of the filters in your particular radio, and if they are off, being right on freq with the IF coil still won't be where the radio sounds best on SSB.

You need a good bench radio that has been confirmed to sound excellent on SSB with the clarifier centered. ham radios are good for this.

now once you get the IF coils close with the previous method, go back and tweak them slightly while listening to yourself on the good bench radio.

you'll find that too far one way sounds tinny and too far the other way sounds bassy.
just align them so the radio sounds good on SSB TX and you're all set.

i find this to work better than trying to just set them for the right freq.
LC

Thanks so much LC!!! I did as you suggested and the side band is on frequency. I do have a question about your bench radio. Do you just have it in the same room with no antenna and transmit the radio being serviced into a dummy load? Did you need to do anything to keep it from overdriving the bench radio?

BTW, I did order one of those RF amps.

Thanks again!!

 

[loosecannon]

glad it worked out for you.

yeah my bench radio resides about 4 feet from where i work on radios.
No antenna connection and the RF gain most if not all of the way down.

Yes there is still some feedback when keying radios into the dummy load and listening on the bench radio.

i imagine some headphones would help, but ive never been much of a headphones guy.
maybe because i have to wear them at work a lot LOL.
LC