GALAXY 959

[OL RED]

MUCH APPRECIATED. IF THE 959 IS GETTING 99% GOOD REVIEWS FROM YA'LL, GUESS I'LL GO ON AND GET ONE TO PLAY WITH. ALSO, IS IT A PAIN TO GET THE CHANNELS LINED SMOOTH UP AFTER GOING TO DUAL FINALS OR NOT? I'VE HAD A COUPLE 29'S (3 OR 4 OVER THE YEARS) THAT JUST SAT A COUPLE NUMBERS OFF (ON THE HIGH END) AND NEVER WOULD SIT JUST RIGHT AFTER A FINAL CHANGE.

 

[lords]

nope channels or dual finals don't affect it...and dude don't compare cobra with this galaxy..thats like saying I had a ford and it had a bad alt ,I hope my chevy ain't the same..2 different worlds,nothing else!

 

[pat]

DX-959

best radio i have had. easy to mod. extra channels, top gun modulator and compressor. d104 hand mic. this radio rocks. nothing but good reports. did clarifier mod. surprising good reports even on ssb. to date i have 5 of them, and would buy 5 more

 

[bighammer]

mine works well on the base. you can tune the recieve by following the pot adjustment order from cb tricks, just by watching the needle, then cut back L2 and L3 1/3 turn to cut back white noise and you will be extreamly happy.

 

[Coax Kid]

DX 959

Hi Guys
I have a 959 and the only thing I didn't like was the white noise in it, Maybe someone has the answer.

 

[Shadetree Mechanic]

mine works well on the base. you can tune the recieve by following the pot adjustment order from cb tricks, just by watching the needle, then cut back L2 and L3 1/3 turn to cut back white noise and you will be extreamly happy.

Has anyone used this technique of tuning L2 and L3 to reduce the white noise? Recently I found where a Galaxy technician recommended tuning L8 to reduce noise. I don't know much about doing an alignment, but I suspect that any of the receive cans can do this? Are certain cans better to use than others, or should this be done to all the cans just a little? What is the best way to do this?

 

[loosecannon]

There is a lot of confusion over which coil to "de-tune" since this cure was originally used for the old RCI-2950 radios.

In the RCI-2950, L8 is the "antenna coil" meaning it's the first one in line after the coupling cap from the antenna jack and before the RF amplifier transistor.

here is a diagram of the 2950:


Here is a diagram of the same section in the DX959:


as you can see, in the 959, the same coil is L5.

just for fun, here is a diagram of the galaxy 99 that uses the EPT3600 series board:



In this radio, it's L6!

so, the way to get rid of the white noise issue in a ranger/galaxy radio, is to find this coil, the one that sits right before the RF amp transistor, and de-tune it by about 1/2 a turn.

this needs to be done with no antenna connected to the radio, and no signal input either.

here's the way i do it.

first peak the receiver with a weak signal from the sig gen, and set the S meter for proper S-9.

then remove any input to the antenna jack, and turn the volume up to a normal level.

now de-tune the antenna coil just a bit.

then connect the sig gen again and check that S-9. if it's off a half S unit or more, i will peak the antenna coil just a bit.

hope this helps.
LC

 

[G-Golly Wally]

There is a lot of confusion over which coil to "de-tune" since this cure was originally used for the old RCI-2950 radios.

In the RCI-2950, L8 is the "antenna coil" meaning it's the first one in line after the coupling cap from the antenna jack and before the RF amplifier transistor.

here is a diagram of the 2950:
View attachment 49373

Here is a diagram of the same section in the DX959:
View attachment 49374

as you can see, in the 959, the same coil is L5.

just for fun, here is a diagram of the galaxy 99 that uses the EPT3600 series board:

View attachment 49375

In this radio, it's L6!

so, the way to get rid of the white noise issue in a ranger/galaxy radio, is to find this coil, the one that sits right before the RF amp transistor, and de-tune it by about 1/2 a turn.

this needs to be done with no antenna connected to the radio, and no signal input either.

here's the way i do it.

first peak the receiver with a weak signal from the sig gen, and set the S meter for proper S-9.

then remove any input to the antenna jack, and turn the volume up to a normal level.

now de-tune the antenna coil just a bit.

then connect the sig gen again and check that S-9. if it's off a half S unit or more, i will peak the antenna coil just a bit.

hope this helps.
LC

I've used a Galaxy dx959 a little, it didn't belong to me, a guy I once new let me talk on his a little bit. But most Galaxy radios I heard on the air sound really good. I could be crazy, but I think the tone of voice makes a difference with at least the Galaxy radios. I new a couple that had a 959, when the husband was talking on it he was loud and clear, but I swear when his wife talked on the exact same radio she sounded twice as loud, I always assumed it was because of the different pitch of her voice.
LC, I still plan on sending my 2950 to you at some point, but every time I get enough extra money to do so, life steps in a has another idea for my money. I'm still in awe of my Madison you worked on. I show other radio junkies pictures of it like it my kid. Lol

 

[loosecannon]

glad to hear the madison is still going strong.

be sure to message me before you send the 2950 as i have a new mailing address for radio work.
LC

 

[G-Golly Wally]

glad to hear the madison is still going strong.

be sure to message me before you send the 2950 as i have a new mailing address for radio work.
LC

Copy that!

 

[Handy Andy]

IF anyone needs to be inspired...

There was a trick used by Uniden back in the days of the 810, PC122 and still works to this day becasue of how the radio tunes for "image" of the RF signal - to obtain IF signal..
You already know

Generalized for brevity...
​

• - only one is higher while the other is lower - between these two is a choice.
• You have mirrors of the original in addition and subtraction - most use the Subtraction (the lower frequency)

Uniden gave the techs a way out the mess by telling them to simply detune the 1St IF coil section - then all they had to do is focus on the RF signal - with a touch of IF to see the image- but not enough to overcome the AGC action and start skewing results.

Its' why you see this in that Service manual...

​

And is still why I recommended you disconnect the PIN Diode feed line from the AGC section so you can see and track the true RF signal you're looking for so the radios' IF section can take care of the rest of the mess.

So L6/L5 mess is the front end and makes any receiver overload - yes, but when you detune the 1st IF coil in the strip - you get to hear the Galaxy LISTEN for the RF emanating from that coil.

So, when you tune that coil - don't make the Radios' "ears" hear too much to start with - that way you can peak out by your own listening choice - the level of signal in the band plan you want to listen for - then work accordingly.

Yes, you will have to detune L5/L6 as needed - but you can obtain a better IMAGE by finding the RF range you Seek, then let the Galaxy/RCI IF processing take on the rest of it.

​

You want to detune and retune the LAST coil into the IF filter of the 1sy IF STAGE because the IF Mixer is amplifying everything.

Just want the IF FILTER to capture the correct Mirror image of the RF to IF conversion.

Then you tune L5/L6 and you can even disconnect the PIN Diode supply line if you wish to reduce the AGC action effectively.

Then reconnect and retune L10 - then as necessary detune L5/L6 as needed - for in doing this step you'll see where the IF noise is maximized, then you can seek the RF signal Out from it - the lower bands the L5/L6 can go is in that IF Noise so you have to make choices on where to set the tuning for your band you want to listen to/for.

ADDED:

This isn't cast in stone, but the process of the Detune the IF first to even allow you to see how the Peaking occurs on the IF strip - the method helps with this.

But only if you have a specific type of IF stage mixer...

Back to the Galaxy​

Although detuning L7 would work, the problem lies in the "twin amp" design of the IF Mixier - with both Sourcing from the Same IF (loaded with a 1.5K each)

In earlier Uniden / Cobra approaches - they had a far different design - effective yet simple.

The FET developed a Difference signal - but uses a Series/Parallel
Cap and Resistor Combo to Sink the results into L14 (PLL 1st IF / TX Out)
And develop the image using L6 sourced from RX power.
​

I'm only pointing this out because others have asked how to offset the Galaxy "Quadrature coil" noise - there is not a "true" way - unless you'd like to use the L8 - L9 - L10 - for L7 - being the output of the RF (26~30MHz ) Amps' Band pass filter - but because of the 1.5K to Source Resistance - the stage cannot discern as well as to use L10 and allow the IF crystal lattice filter pass the mess

In the typical Uniden SSB chassis of the PC-122 series - the Realistic version skips this instruction...

They went brute force and only used AM...​

​

So the point of the post is...

Reduce the IF signal as much as possible - disable AGC as needed - to obtain the most open sensitivity the Receiver could have - to offset the tuning "noise" the Galaxy L5/L6 Quadrature coil injects by design,

OR...

Detune the RF AMP Bandpass filter stage BEFORE the IF - If the FET section will allow it.

​

 

[Shadetree Mechanic]

IF anyone needs to be inspired...

There was a trick used by Uniden back in the days of the 810, PC122 and still works to this day becasue of how the radio tunes for "image" of the RF signal - to obtain IF signal..
You already know

View attachment 49378
Generalized for brevity...
​

• - only one is higher while the other is lower - between these two is a choice.
• You have mirrors of the original in addition and subtraction - most use the Subtraction (the lower frequency)

Uniden gave the techs a way out the mess by telling them to simply detune the 1St IF coil section - then all they had to do is focus on the RF signal - with a touch of IF to see the image- but not enough to overcome the ACG action and start skewing results.

Its' why you see this in that Service manual...

View attachment 49379

​

And is still why I recommended you disconnect the PIN Diode feed line from the AGC section so you can see and track the true RF signal you're looking for so the radios' IF section can take care of the rest of the mess.

So L6/L5 mess is the front end and makes any receiver overload - yes, but when you detune the 1st IF coil in the strip - you get to hear the Galaxy LISTEN for the RF emanating from that coil.

So, when you tune that coil - don't make the Radios' "ears" hear too much to start with - that way you can peak out by your own listening choice - the level of signal in the band plan you want to listen for - then work accordingly.

Yes, you will have to detune L5/L6 as needed - but you can obtain a better IMAGE by finding the RF range you Seek, then let the Galaxy/RCI IF processing take on the rest of it.

View attachment 49380​

You want to detune and retune the LAST coil into the IF filter of the 1sy IF STAGE because the IF Mixer is amplifying everything.

Just want the IF FILTER to capture the correct Mirror image of the RF to IF conversion.

Then you tune L5/L6 and you can even disconnect the PIN Diode supply line if you wish to reduce the AGC action effectively.

Then reconnect and retune L10 - then as necessary detune L5/L6 as needed - for in donig this step you'll see where the IF noise is maximized, then you can seek the RF signal Out from it - the lower bands the L5/L6 can go is in that IF Noise so you have to make choices on where to set the tunnig for your band you want to listen to/for.​

Ok, I think I get it. The white noise, hash, bacon sizzle, noisy receiver is the noise of IF conversion / mixing. We want to hear the RF signal, not the radio. So why do we use a tone to set the receive cans when we do not listen for tones in DX land?

Maybe we should use an audio signal instead of a tone. Like a voice recording. Maybe use a recording of words that is easy to make out, and peak everything. Then use a recording with words that are hard to copy, and peak that way again?

What would we end up with?

 

[loosecannon]

I see your point Andy, but wouldn't just inputting a super low signal in the first place take care of that AGC action anway?

im talking on the order of say, 1 or 2uV with a tone.

like i said, i see why you are mentioning removing the AGC PIN diode, but i do have to wonder just how much better a result you would achieve by going to the trouble.
that being said, ive never tried doing that.

one thing i can say is that while you could probably get away with tuning for "max reading on AF VTVM" with all the old uniden chassis, having a SINAD meter when tuning up a Ranger chassis is a completely different world.

it's like these Ranger receiver designs have all the gain in the world, but the filter shaping and the lack of "discrimination" (no pun intended!!!) give them a "cheap" sound.

Sometimes i wonder just how many people have opened up a Ranger radio, tuned the receiver for max S-meter reading with no signal input, and found themselves listening to a radio with nothing connected to it, and an S-meter reading of S-4.
LC

 

[Handy Andy]

So why do we use a tone to set the receive cans when we do not listen for tones in DX land?

Because of the very reason tone helps some people during the tuning process - to pick out and discern the actual signal.

There are also other aspects others tend to gloss over - but one is how the Detected Audio can be used to "spike" the signals strength.

​

There is a metering function that uses the Audio signal combined with the carrier to act as a Doubler - just so the meter can pick up and amplify the signal for AGC use - don't want some of the louder stations drowning out those that have a signal - but not as strong in envelope strength - or in some instances - they only have the audio present in the envelope and it manages in crossing the antennas' finish line and it's all you hear out of the QRM.