Galaxy DX Series Improvement

[Larry A McClanahan]

This will improve the RF and peak output on DX-929 thru Dx-979.
The ones that are used in these radios are only rated at 300mw.
Q-52.
Replace with a 2sc1973. The same one that is used in Cobra 142, 148, and 2000. Rated at 750mw, 1 watt typical.
Replace R-253 with 18ohm
If you are running a dual final radio, you are going to love this modification.
I don't know how everyone else feels, but I really like using the palomar Max mod. I have yet to have any blow out on my radios.
The radio always runs cool.

 

[Dzbullrider]

Think I'll give it a try

 

[Larry A McClanahan]

Think I'll give it a try

Let me know how it works for you. It worked great for me on 3 different radios.

 

[Eldorado828]

Your mod has me curious. So what kind of performance increases are you seeing? Is it increasing heat, because most of these modern radios just run way hot even before modding

 

[Handy Andy]

Well, the Datasheet is in Asian...

But there's this...

The Datasheet is amalgamated with other parts to cross reference...
But...They use this Test Jig...



So far so good...


There will need to be some changes though...
MOSFET chassis is biased differently...

​

@Larry A McClanahan - Check your R249 - see if reverting this back to a 56 ohm on a ferrite BEAD helps - C218 is an NFB but should use two parts - similar to the 1306 of the 148/139XLR ( Cobra) and 2166 of the HR2510 - if you use High gain FET's like 13N10's - they will need the above parts in at C218 - R249 is optional - R253 - per your mod - is also fine...

 

[Larry A McClanahan]

Well, the Datasheet is in Asian...

But there's this...

The Datasheet is amalgamated with other parts to cross reference...
But...They use this Test Jig...
View attachment 39007
View attachment 39008

So far so good...
View attachment 39010

There will need to be some changes though...
MOSFET chassis is biased differently...

View attachment 39011​

@Larry A McClanahan - Check your R249 - see if reverting this back to a 56 ohm on a ferrite BEAD helps - C218 is an NFB but should use two parts - similar to the 1306 of the 148/139XLR ( Cobra) and 2166 of the HR2510 - if you use High gain FET's like 13N10's - they will need the above parts in at C218 - R249 is optional - R253 - per your mod - is also fine...

Will try to find time tomorrow to check this info out. Looks promising.

 

[Eldorado828]

This will improve the RF and peak output on DX-929 thru Dx-979.
The ones that are used in these radios are only rated at 300mw.
Q-52.
Replace with a 2sc1973. The same one that is used in Cobra 142, 148, and 2000. Rated at 750mw, 1 watt typical.
Replace R-253 with 18ohm
If you are running a dual final radio, you are going to love this modification.
I don't know how everyone else feels, but I really like using the palomar Max mod. I have yet to have any blow out on my radios.
The radio always runs cool.

Since all of the current 929-979 are mosfets but hasn't always been so is your test specimen bipolar or mosfet? I ask because Andy brings that up in his text above.

 

[Larry A McClanahan]

Since all of the current 929-979 are mosfets but hasn't always been so is your test specimen bipolar or mosfet? I ask because Andy brings that up in his text above.

Mosfet

 

[Larry A McClanahan]

I have a new Dx-99v2 on the way. Will do this modification And document the Before & After.

Is there an accurate schematic available for the DX99v2?

 

[9C1Driver]

So what exactly are you claiming is improved? Will you get 10-15 more watts? Are you claiming more audio? It might seem like a great idea for some but just look here on the forum how many times you see where someone gets a used radio and it has some crazy mod in it they want un-done. I bet if you took your brand new Dx-99v2 and did a complete factory alignment it would sound superb and have great receive.

 

[Larry A McClanahan]

The factory alignment after the clarifier is unlocked is a definite. The purpose is to be able to drive my DX 1200 better than I am currently doing with a single final radio. I don't want to drive it with a modulator. It will increase the RMS and the peak.
If I can double what I am currently driving into it I will be content.

 

[Handy Andy]

Hmmm...

The purpose is to be able to drive my DX 1200 better than I am currently doing with a single final radio.

Single Final?

I don't want to drive it with a modulator. It will increase the RMS and the peak.

ULP - Modulator?

If I can double what I am currently driving into it I will be content.

Ok, we need to talk...

Before I get my butt slammed for trying to help "Polish another turd" using Cadillac parts into the ol' 75' Chevy Nova...

• Interesting (anecdotal) point...The Model name "Nova" used as a Badge by Chevrolet WAS NEVER A BIG SELLER in France or in Europe...
  • Why?
    • NOVA in French interprets as "NO-GO" (Dying Stellar object)
    • Do you want to own something that when it gets old, it explodes?
    • Not saying your old Chevy will explode, but that is what GM tries to sell you.
    • Hello - Ford? Do you still offer Pintos?

So with the above being said, you already posted a mod to up the power level of the Galaxy series using Dual Finals and now you're saying your using a SINGLE FINAL radio to drive this DX 1200...

Ok, you realize how "awkward" this looks...

​

So, I don't know if it's me, or am I seeing something - er, not just Awkward, but inconsistent...

What is in your mods that isn't working - let's sort this out...(I hope)

 

[Larry A McClanahan]

Not really looking for help. Here's the situation. I am currently running a single final radio. Driving a DX-1200 with a single final radio. I have a dull final radio on the way. I know from 40 years of experience that installing a 2sc1973 in place of the stock device ups the final output.
Same device that is used in the Cobra 2000, Cobra 142, and the Cobra 148. Has never blown anything up and is clean on the scope. I don't wanna hit the amp real hard.

 

[Handy Andy]

Oh, ok, that makes sense...

I don't wanna hit the amp real hard.

You had mentioned earlier about the 1973 Pre-driver, which I happen to agree with you 100% that the upgrade (really a backwards compatibility issue) is a necessity - especially when using a Radio for Free-banding.

The 1906 - in itself - works fine for in-band use - and yes drive is not there as many would like to have what they use a Galaxy for, it's modulation (amongst other features). But that is the price that's paid for even being able to sell the radio.

They are not telling you - you can't do it, they just can't sell the radio with it in due to the emissions issues with such a radio design.

If you notice, the older boards used an Idealized design platform.

​

Doesn't mean you'll get it to do that which you think it will, but it's closer than "Best Guess" methods.

Now in converting the older platform designs (all those holes and parts layouts) and yet still work, they compensate the effort with a different approach - working from the Back to the Front - because of the changes in the parts supply chain, they did this; but had to change that - to get this to work - approach.

They...

​

So they had the basics, they needed to work and have it produce like their older cousins, only now they had to optimize that which they had, using available methods and parts.

So, when you see this...

But have only this...

As your template...​

The design is still there, only buried in modifications to make the newer design fit (OPTIMIZED to) what the older IDEALIZED design did for a long time.

So when I mentioned the mods, there are what they are to offset the shortcomings of the newer designs inherited flaws from their design the originally had completed. It' was not perfect but it did the job. Now, they need something to work, so they took what they knew, and OPTIMIZED for the root layout.

It's why I posted those mods, you have all you need in front of you - just put in it a configuration that reverts Biasing and parts back to an original design but remember you are using newer parts in this very same layout.

 

[J_man]

Does anyone have a write up of the dual irf520n finals in a DC 959? Any help would greatly be appreciated. I have looked in the older threads but it wont bring anything up other than saying it was suspended