Galaxy DX959b Question

[KD8HMO]

I was in a cb shop last week and was talking to the tech about my 959b. He said when he aligns that radio, they set the 10.240 reference circuit, which I know about. He also mentioned a 455khz adjustment. This is not mentioned in the service manual. Anyone know what he was talking about?

 

[sonoma]

FL1 is the ceramic crystal filter for the 455hz feed to the radio. more than likely he is talking about the osc adjustments. .if you go in some place and try to act like you know every thing about a radio they will just spout out numbers and stuff to see what you know..
my buddy has a shop and guys will come in wanting to see if they can get info from them to adjust their own radios and he does not give out any info to a guy wanting to do their own work.. they are in business to make money so they will not give you any real info to go home and try to do the work your self.

 

[loosecannon]

sure, he's talking about L2 and L3 which are part of the 455khz IF section.

In other radios, a 455khz signal is injected into that stage and those coils are peaked at that freq.

Galaxy just doesn't bother doing that and peaks them with a 27mhz signal at the antenna jack.

I have honestly never tried doing that to these radios, but i will be giving it a try next time i have one on the bench.

Does anyone here inject the IF freqs into galaxy style chassis and align them that way?
LC

 

[Robb]

Does anyone here inject the IF freqs into galaxy style chassis and align them that way?
LC

Not me; I'm chicken!
lol

 

[Tallman]

Does anyone here inject the IF freqs into galaxy style chassis and align them that way?
LC

I never do that unless the front end of the radio is dead or very weak. I prefer setting the PLL to the proper frequency and going from there. Unless you have a very, very good signal generator that is calibrated and stable might be more trouble than it is worth. I have one signal generator that is that good but very rarely use it.
I do use it to get the front end aligned but not injecting Intermediate Frequencies.
Some radios like my Ic-7100 is a triple conversion so the IF injection would be a waste of lab time.

 

[loosecannon]

I never do that unless the front end of the radio is dead or very weak. I prefer setting the PLL to the proper frequency and going from there. Unless you have a very, very good signal generator that is calibrated and stable might be more trouble than it is worth. I have one signal generator that is that good but very rarely use it.
I do use it to get the front end aligned but not injecting Intermediate Frequencies.
Some radios like my Ic-7100 is a triple conversion so the IF injection would be a waste of lab time.

thanks for the reply Tallman,
As an example, i find that when aligning the MB8719 chassis, if you just inject a 27mhz signal in to the antenna jack, and then just tune for max S-meter reading; that you end up with a noise level of almost S-3 when the radio is connected to an antenna.

when i actually inject a 455khz signal in, and then a 7.8mhz signal, then finally a 27mhz signal for the front end, all using a sinad meter, i end up with a lower noise floor.

LC

 

[Robb]

thanks for the reply Tallman,
As an example, i find that when aligning the MB8719 chassis, if you just inject a 27mhz signal in to the antenna jack, and then just tune for max S-meter reading; that you end up with a noise level of almost S-3 when the radio is connected to an antenna.

when i actually inject a 455khz signal in, and then a 7.8mhz signal, then finally a 27mhz signal for the front end, all using a sinad meter, i end up with a lower noise floor.

LC

FWIW, I just make sure the first receive tuning coil is kept way down low, as this has the greatest amount of noise potential at that stage - AFAIK. I use SINAD to gauge signal vs noise vs distortion. Seem to hit the mark.

 

[sonoma]

when Ray was the tech for Galaxy he always said for the noisy RX on their radios to unhook the antenna, crank the volume all the way up and turn L8 clockwise about 1/4 to 1/2 turn but just until the noise would go away. most of them will have static with the antenna unhooked and the volume all the way up.

 

[loosecannon]

FWIW, I just make sure the first receive tuning coil is kept way down low, as this has the greatest amount of noise potential at that stage - AFAIK. I use SINAD to gauge signal vs noise vs distortion. Seem to hit the mark.

I'm not sure i fully understand. are you saying that you don't peak L4 (148GTL)?
I feel like i am just not getting it.

when Ray was the tech for Galaxy he always said for the noisy RX on their radios to unhook the antenna, crank the volume all the way up and turn L8 clockwise about 1/4 to 1/2 turn but just until the noise would go away. most of them will have static with the antenna unhooked and the volume all the way up.

I always do this too, and for the exact same reason.
Boy that guy Ray was a big help to a lot of us trying to understand those chassis.

sonoma, do you have any of Ray's posts on this subject saved?

The reason i ask is that L8 is not the same coil in the 959 as it is in say the 99v and other exports, and i can't remember without searching through a bunch of old notes which chassis he was referring to when he said "L8".

LC

 

[sonoma]

he has a lot of it on the repair section for cbtricks.
symptoms and cures data base

 

[loosecannon]

thanks Sonoma.

by checking the galaxy symptom and repair guide, i was able to confirm that it is indeed L8 in the 959 and other 6900 series boards.

however, it is not L8 in the 3600 series boards. the circuit is a bit different and i believe L10 to be the correct coil in these chassis.

any clarification to this is most welcome!

also found this little gem that i forgot about:

EPT6900-10C
Symptom Symptoms:
1. Several S-Units of noise on meter even on quiet nights.
2. Large jump in S-Meter signal when driving under power lines or sodium lights.
3. RF Gain fully counter clockwise causes receiver static. (big one)

You will mainly notice these symptoms when connected to an outside antenna and not a dummy load.
Cure Cure:
L7 is not aligned correctly.

Recommendation:
Adjust L7 fully clockwise until the core bottoms out.
Then turn counter clockwise one full turn and stop.
Adjust L5, L6 and L8 as normal for max signal to noise.
Additional Comments Covers following models:
DX45
DX48
DX93
DX95
Category RX
Posted By Galaxy Tech Support

this would also apply to the DX959 and its counterparts.
LC

 

[Robb]

http://www.cbtricks.com/cgi-bin/database/galaxy_db.cgi?details=1&key=89

Says this phenomena only works for a few models. But if you look at the 959 schematic, that part of the RX circuit is the same as the other models mentioned.

 

[sonoma]

if memory serves me right this is also for the 93T and 95 radio. when I 1st got this info from him was on a 93T I had just bought. talked to him on the phone about it.

 

[sonoma]

the last time I talked to Ray was mid year of 2007. I was in the process of moving back to Oklahoma from Michigan. I did not have internet again until 2010 and he was gone. sure do miss his info.