$3 For Better DX-959 Stability?

[Robb]

When I left technician land years ago, we would call it shotgunning. It had about a 10% success rate, just for replacing a failed part. I gave up that approach quick. Another thing I learned when trying to troubleshoot closed loops is that components that affected loop lock and noise the most were typically not the problem components. if this is not understood, then use of freeze spray and heat guns can easily lead one astray.

Does this circuit even have temperature compensation feedback? How does the basic design (block diagram) differ from the references (whatever radios people are using as their holy grail of stability, what? a 148?)

not trying to mislead or misinform

I understand; that wasn't leveled at you C2; meant for the Galaxy engineers..
Just borrowed your points - is all.
Sorry for the misunderstanding.

UJ ceramic caps - by design and intended function/use - is to compensate:
http://search.murata.co.jp/Ceramy/image/img/A01X/G101/ENG/GRM0333U1H6R0DD01-01.pdf

 

[Robb]

You have to take all of the support systems into account when modifying one particular circuit loop. I for one would like to see a Galaxy that's stable on freqs. Shoot,I'd sent my 959 for modification to ROBB if he can make one perform better.
By the way Robb,those modifications you're doing could be a closely guarded secret supposing you were going into the radio mod business. Snake Radios did the same thing. I think people are willing to pay someone knowledgable who can mod a radio in a good way.

My info is not for sale nor was it ever intended to be so. I repair/align local radios for ops and do not charge anything, except for parts if/when needed. I have worked on a couple of 'Snake-ified' radios and sent them out the door in good repair.

I am new to radio work and by all means and am certainly no tech or engineer, just a hobbyist/consumer. The info I brought up in this experiment was to find a simple solution for a radio that is used in great numbers in different packaging. Whether someone else can crack it or not, I can only hope they do and share their findings.

 

[unit_399]

OK, now it is time for me to eat some well-deserved crow here.

Don´t do it , Robb. At least you gave it a try, which is more than anybody else (me included) on the forum has done. Keep up the good work. 73s.

- J.J.

 

[C2]

yeah, I agree. Nothing ventured, nothing gained. This is a good reference regardless. Is someone able to isolate the loop schematic?

 

[Lil'Yeshua]

My info is not for sale nor was it ever intended to be so. I repair/align local radios for ops and do not charge anything, except for parts if/when needed. I have worked on a couple of 'Snake-ified' radios and sent them out the door in good repair.

I am new to radio work and by all means and am certainly no tech or engineer, just a hobbyist/consumer. The info I brought up in this experiment was to find a simple solution for a radio that is used in great numbers in different packaging. Whether someone else can crack it or not, I can only hope they do and share their findings.

I know,it would make a good idea for whatever anybody would do if they wanted to go in business for themselves. I appreciate you going the extra mile in seeing if you can make a better Galaxy or any other radio.

 

[Robb]

yeah, I agree. Nothing ventured, nothing gained. This is a good reference regardless. Is someone able to isolate the loop schematic?

Ummm, sure.

 

[loosecannon]

I for one am really happy that you actually tried all this.

we all love to pontificate on what could be done to help the Galaxy style radios, but most of the time it stops right there.

years back, i tried putting metal shielding on the solder side of the PC board in strategic areas, doubling up filters, adding braid to make up for very thin PC board ground traces, replacing the input "hash" filter transformer with a better one, and im sure a couple of other off the wall ideas.

none of these made much of a difference (i did cure a light dimming issue, and i still think the input "hash" filter is underrated) but hey, if i didnt try i wouldnt know what wont work! LOL

oh yeah, a friend and i also came up with an add on for the noise blanker circuit, that added a second tuning can to it, essentially making it the same as the 148gtl noise blanker.
this did improve the noise blanker, but the radio still sounded the same on receive for the most part.

someone out there still has my old 959 with this mod done to it.
whoever i sold it to has a real one of a kind radio there.


Robb, your experiments did make me think about the tuning can "touchiness".

if you start reading lou franklin's book as it pertains to clarifier mods, i think there are some mods that broaden the tuning of some tuning cans.

maybe these techniques could be applied to the cans in the L.O. to make them less touchy, and hence, more stable.
hmmm...

good stuff Robb, keep up the good work!
LC

 

[Robb]

Hey thanks guys, for all of the positive feedback.
I'll just try harder now.

 

[SMILEX2692002]

Snake Radios did the same thing. I think people are willing to pay someone knowledgable who can mod a radio in a good way.

That Snake Raidos guy told a customer on a video I watched the price to do his Cobra 148 gtl could go from 2 bills to $700.00.
$700.00 to modify a Cobra 148 gtl that is unbelievable. What would it look like when he was done a Christmas tree?
Can you say Yaesu,Kenwood,Icom price range.

 

[Lil'Yeshua]

That Snake Raidos guy told a customer on a video I watched the price to do his Cobra 148 gtl could go from 2 bills to $700.00.
$700.00 to modify a Cobra 148 gtl that is unbelievable. What would it look like when he was done a Christmas tree?
Can you say Yaesu,Kenwood,Icom price range.

If someone sends him a radio and he finds out that something else needs fixed/customized then yes,I can believe that. Think of it as a car garage in the same terms. You can always say NO.
I've chatted with him once on his webcam site that he provides his customers/potential customers to look over his shoulder and interact with him while he's working on radios. That's back when I was looking around for a reputable tech to do a proper alignment on my 959 until I found Worldwide and well seasoned advice here. I like Christmas tree lights myself.
I would indeed buy a FT-897D as opposed to buying a heavily modded CB but to each his own. Mr Snake is still member on this forum as well.

 

[SMILEX2692002]

I enjoy real Christmas tree lights. When it comes to a CB radio I can't see putting that kind of money into it. If you have deep pockets and really enjoy all the lights and colors and mods he can put on your radio than go for it.
I do enjoy watching his videos to see what people are doing to there radios ect.
I will agree he goes above and beyond what the current Cb/export radio companies call a quality control check.

 

[Inquietude]

Robb,
I have worked on a DX2547 that belonged to a friend and I reduced the frequency drift by 7-10x. It is a very long story but I recognize exactly where in the process you are because I was there myself. The radios frequency is basically temperature dependent, to put it another way. I didn't know what all the talk was over the years on the internet about "drift" since I never owned a Galaxy, and the SSB rig I've used the most over the last 21 years is a Cobra 146 (if it drifts, I can't tell whatsoever--clarifier never ever moves). Anyway, after experiments and measurements it was obvious: ambient temp up=frequency down. I went through many drawing board ideas and thoughts but the answer was in my 1995 Handbook. Also, you'll see it in different web pages usually by hams trying to stabilize an old rig or some homebrew vfo they built. Google: "A Look at VFO Drift in the MFJ QRP-Cub." Also have a look at WA0ITP's book "Crystal Sets to Sideband" chapter 10, which is online in .pdf at the qrparci.org website.
In a nutshell, what I found was that the drift is most likely being caused by a change in permeability of the slugs in the tuning coils. This was found experimentally after reading of the possibility. At any rate, the solution is far more important than the cause of the problem. Galaxy, IMO, put SOME temp compensation in the radio with the UJ caps but not enough. Why did they stop where they did? Because: 1.the first thing everyone does when they open the box is unlock the clarifier. 2.charlie only requires .002% freq. accuracy (that's 540Hz at 27MHz, yuk!). 3. you never get more in a cb than absolutely necessary, and that's industry wide historical practice. Therefore, I INCREASED the compensation by replacing caps that drifted more than the uj's in order to counteract the inherent drift in the radio. It took a very long time to arrive here but: I replaced C130 with a 22pf P3K(n1500) and replaced C281 with 3x 33pf caps: 1@ uj (n750) and 2 @ R3L (n2200). That last one gave a "custom" TC and they were installed in the original location, plus in the unused j28 & j29 positions. The drift went from approx. 400-450Hz between 65-90F down to approx. 40Hz over that temp range. The owner finally got it back and was tickled to death over it. The caps came from Mouser, about $2 actually. I never got around to writing up what I did, so when I saw your posts (and heard you on the radio discussing it!) I wanted to share it with you. There's a bit more so email me. Out of time for now. 73 and good luck.

 

[Robb]

That is great!
Instead of a PM or email, please write up the details here when you can.
Once I have all of the info, I will duplicate your work and verify.
Many Thanks!

 

[loosecannon]

Welcome to the forum Inquietude!!!

cant wait to see what other insights you may have.


all, Snakeradios does not have any closely guarded secrets.
every single thing he does to a radio he got off of the internet.

to each their own, and if they want to have their radio done by him then go for it.
be aware though, that 99% of his customer base is completely uninitiated in the ways of radio repair, and therefore are very susceptible to being taken advantage of.
ive seen with my own eyes in his videos where he describes having to replace a part for some odd reason, when there is no logical reason for doing so.

all im saying is be careful. call another tech, ask them what they think of his reasoning.
post a question on this forum or another. just do your homework and dont get screwed by paying for things that didnt need to be done.
LC

 

[Lil'Yeshua]

Just know the usual salesman tactics and don't get conned in and pay more. Knowledge is key but wisdom us the principle thing.