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How to perform the 2sc2999 and Schottky diode swap

Your all not understanding the comparison,, ok! the road talker hears ppl talking and the texas ranger don't and it is about 4 s units on the road talker before the texas ranger even receives what the sears is.. I took the kits out and re installed the old stuff. and the recieve did pick up a little on both, BUT so did the white noise. that was the only thing the mod did, was get out the white noise. I have a guy I try to talk to, and he hits me with about 1/2 a s unit or less. I turn on the road talker and he is Louder and hits me with 5 s units, I know meters are not what to go by, but it is all I can use for senarial. so I was hoping the mod would help pull him in better but it did not, I lost him totally. I Mean how can one do it wrong? the diode has the cath line on one end and the transistor EBC all in the same place as the original/ not like some NTE ones.

OH yea, that guy in PA is gonna re do everything, take those diodes out and I guess put the 1n60's back in, he told me on the phone to never do those on line mods.. what can I say. for me it didn't work. and I made sure I got the 3.00 sanyo transistor.
 
skybolt58 said:
It may just be the way the meter reads. A radio meter can be adjusted to show anything you want. Every radios meter will show something different. My first guess is that that the 696f has a tighter meter.The 696F's come with the receive already tuned about as good as it will get from the factory. We do not offer any receive upgrades. Beware, if you look for upgrades people will sell them to you whether they help or not.

I am not familiar with the upgrade you mentioned.

If you want a second opinion call Don's Cb in PA. They do repair warranty "present or past" for Ranger, Galaxy, Connex and General radios. They do good honest work. We farm some of our repair work out to them. 814-898-1046

Thanks,

Wes



GI Joe's Radio Electronics

Hi, I got this radio, and it don't receive as good as my old sears road talker 40 slant face ssb base mobile.. the sears gets 3-4 s units before the ranger even starts to receive. is there a way to get this radio to receive as good I had the 2sc2999 transistor upgrade with the diodes also.. Seems like it got worse? the radio is about 5 years old, and it has been this way since day 1.
Click to expand...


skybolt, at this point im a bit confused as to what you actually saw as the problem.

"the sears gets 3-4 s units before the ranger even starts to receive."
can you explain exactly what you mean by this?

im wondering if you might be misinterpreting something.

the more details you can provide the better. i want to address the roadtalker comparisons, but i need to know exactly what you are experiencing at this point first.


now, as for what GIjoe electronics said to you; he is full of crap.

"A radio meter can be adjusted to show anything you want."

that is true.

"Every radios meter will show something different."

this is sort of kind of true in a way, sometimes, but without a long explanation, suffice to say that the meters in radios can be set correctly and will read somewhat the same afterward.

"The 696F's come with the receive already tuned about as good as it will get from the factory."

that is just utter BS. ALL cb radios are mass produced and given the absolute minimum tuning attention possible because that requires an actual person with knowledge and skill.
the only thing they really pay attention to is that the radio wont key up with more than 4 watts and that the modulation cant possibly exceed 100%.

every CB radio can benefit from a full alignment, and i have yet to come across one radio that was tuned right from the factory.
sure, they work, but they are stunted.

"I am not familiar with the upgrade you mentioned."

now that just scares me right there! they guy in charge of tech support for GIJOES doesnt know about the schottky diode/2999 upgrade?

either he's been living under a rock, or he's lying.


lets try to back up a bit here, get all the info we need to help you, and i bet you will be happy with all your radios.
LC
 
if you installed the kit incorrectly, you could definitely get the results you described as far as the lack of sensitivity.

you also need to re-align the receiver section after the mod.

having don go through the radios is a good idea.

i am surprised at don telling you not to do that mod.
my guess is that he was making a blanket statement about not trusting what you read online, and he is to be heeded, but the schottky diodes are an upgrade no matter how you look at it.
the only reason they dont do it at the factory is that the diodes cost too much.

good luck with them, maybe you should send your roadtalker to don also so he can figure out why its got super receive. LOL

be sure to post back when you get the radios back so we will know how it all worked out.


oh, just wanted to add, in those radios, you should be replacing Q17, D1, D2, D30, and D31.
just want to make sure we are all on the same page.
LC
 
NOOOOOO the road talker is working so leave it alone,,,


Well I did also put it into my general grant, and it seems a little better in that, not much tho, like on defproms page says..

the 696f is a great talker, but no ears, I also mentioned about the super ears mod, and thats when Don yelled at me.

as I mentioned in my very first post, I brought both radios to a tech that is rci cert. cost 40 bucks each, did the 696f and the 959. and like I keep saying I just cant hear that guy out in the dinky weeds. I tell ya it is agravating. Tim checked my work and all was in right, he too has installed them, I just got 2 bad radios. I have a washington 858 also, did it to that and no help also, I have to do what I found on cb tricks about the tr5 failer on that some day. but I am not undersdanding wher it is saying to put the 2 diodes.

Yes, I did the right transistor and diodes. the grant was differant tho


do you think RF parts sent me cheaper transistors?
 
Cobra 19 Plus and 40 Plus

For the 19 Plus, the RF amp transistor is Q101. The detector diode is D103 and the ANL diode is D106. You could also replace the AGC diodes as well: D101 & D102.

In your 40 Plus, the RF amp transistor is Q101. The detector diode is D108 and the ANL diode is D110. AGC diodes are D101 & D105.

Since Schottky diodes are faster switching, the replacement of the AGC diodes could better protect the radio from overload from very strong signals. Not that you would have to do this, just that while you are in there it is something to consider.

IMPORTANT: The Sanyo 2sc2999 is NOT a drop in replacement for either of your radios. Both the 19 Plus and the 40 Plus use an MPS9426(c) transistor for the first RF amp stage. Both the MPS9426 and the 2SC2999 are NPN transistors, but the leads are different. You will have to reconfigure the leads on the 2999. Looking at the flat side of the transistors, with the leads facing downwards, the leads are as follows from left to right:
MPS9426 (c): B, center lead is E, C
2SC2999: E, center lead is C, B
(B: base, C: Collector, E:Emitter)

Just carefully bend the leads as required and make sure that they do not touch one another after the component is soldered in place. You could also install the 2999 so that the flat side is opposite from the 9426 and only have to bend the leads for C and E. Many radios use a 2sc1674(L) for the first RF amp.... and then the 2999 is a direct "drop-in" replacement.

Just so that you know what to expect, I think many people expect drastic improvements in their receiver. Realistically, expect a noticeable difference in the noise on weaker signals and perhaps a 1/2 to 1 S-unit improvement on the weaker signals. Stronger signals won't show any discernable difference on the S-meter, nor to the human ear. Every radio is different and results may vary, but I have been very happy with all of the radios that I have performed the mod on. Of course be careful in removing the original stock components and if you are not happy with the results of the mod, you can always return the radio to original. Good luck!
 
Ronin, never thought to consider the AGC diode change out.
These are the 1N60P's you are referring to - right?

I also changed out the SSB transistor with a 2sc2999e in the Galaxy DX99V used in the mobile. Aligned the radio as per spec'd on CB Tricks. If it wasn't for this radio drifting as much as it does, it would be one of the best receive radios I use - AM or SSB.

The radios using the 2sc1674L in the 1st SSB detector stage will also benefit by replacing it with a 2sc2999e. Makes a marked improvement in SSB clarity. Also recommended. Might cost a little more to do both the AM and SSB transistors; but well worth the time and expense - IMO
 
Hi Robb, In the Cobra 19+ and 40+, it appears that they are using 1s2473 diodes, which has basically the same specs as the more common 1n4148 (which is also a direct replacement). Even though the 1s2473's and the 1n4148's are regarded as "fast swicthing" the Schottky still seems to be the better choice.

With my DX-949, the 2sc2999 in place of Q20 (which stock is a 2sc1674L) for the SSB worked nicely. But, on my Uniden Pro 810e, the 2sc2999 seemed to be too much. The stock transistor in the 810e's SSB is a 2sc945A-Q. What I did then was replace Q13 with the 2sc2999E, then take the 2sc1674 (from the RF amp at Q13) and drop it in the SSB det amp at Q11. That worked very well.

The Uniden 810e was an excellent SSB radio right from the start, but the AM suffered from rather poor signal to noise ratio. After the mods, it is excellent in both modes. The DX-949 on AM improved quite a bit and the SSB is excellent now....virtually no noise at all and signals really jump out.

At one point I had borrowed a friends new stock (only aligned and tuned) DX-2547 for comparison with my DX-949. I ran it only a few hours and packed it back up. If I had to listen to the stock receiver on AM or SSB (after the modded receive on the 949) it would probably drive me nuts. I would like to get a new DX-2547 since they are the only 11 meter base radio right now, but I would have to do the receive mod as soon as I got it, then do the align and tune. I guess I am spoiled now with the receive mods! Lol! :)
 
there is something that i think should be mentioned in this thread for the benefit of future readers/modders, and who knows, it might have happened to someone already.

schottky diodes are very sensitive, and can easily be damaged internally just by cutting the leads.

one should never "pre-cut" the leads before soldering them in the radio.

i was told that using a scissor type of cutter instead of the "dykes" style of wire cutter was a requirement.

i do not use one, i just use the "dykes". (not the right term, but you get what i am talking about)

the secret is to carefully bend the leads, put the diode in place, slightly bend the leads so the diode will stay put when you turn the radio over, and solder the diode in.

then, after the diode is soldered in place, gently cut the excess leads off, using only as much force as is required.
the idea is to "squeeze" the lead apart instead of "popping" it apart.
LC
 
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Robb is absolutely right that you HAVE to use a 2SC2999E transistor to get the most out of this mod. This transistor is rated as having an Hfe (current gain ) of 40 - 260 (approx). Sanyo grades these transistors with C, D, and E suffixes. Each has a different current gain range, with the E model being the highest. (Hfe= 140 - 260) Since almost all original equipment front end transistors have an Hfe of 100 or better, replacing it with one with less gain is a waste of time. The ECG and NTE 107s are rated Hfe of 80 (typical), and will work if you're lucky and get a good one. Most of the run-of-the-mill replacements out there are made in India or Russia, and are hit -or-miss gain-wise.
I called Sanyo International Sales to find a distributor in Colombia who had the "E" models. I know RF parts has them in the states, and I would trust parts from them. Other places... dunno.

- 399
 
unit_399 said:
the 2SC2999 transistor is rated as having an Hfe (current gain ) of 40 - 260 (approx).
Click to expand...


I was away from home when I made my last post, and got the figures for the 2SC2999 wrong. Actuallly, the Hfe range is 40-200, and the current gain ranges for the C, D, and E versions are 40-80, 60-100, and 100-200.

The 2SC1764L which is standard equipment in most high end CBs and Exports is rated Hfe = 90-180. So... If your rig happens to have a really good 1764L, and you replace it with a so-so 2999E, there could actually be a decrease in performance, because decreased gain = decreased sensitivity. The best solution is to use a VOM with a built-in transistor tester and see what you got. The 2SC1730L in my 858 rig measured an Hfe of 96. My distributor here let me go through his bin of 2999Es and cherry-pick the 50 best. Most were in the 160-180 range. Of the 200 or so I checked, the best one measured 183 on my meter.


BTW... There is only a 1db difference in Noise Figure between the 1764L (3db) and the 2999E (2db). This is barely discernible. So just make sure the transistor that's in there has really high gain. If you have a 1764 with a Hfe of 130 or better leave it alone and just do the schottky diode mod. Anyone out there REALLY know why the schottky diode mod works??
- 399
 
Last edited:
Robb said:
I was told - for what its worth - the the Shottky's switch on faster and sooner.
Lower threshold?
Click to expand...


That's pretty much it. I think it's because the turn-on voltage of the shottkys is much lower than the stock germaniun diode, so a weak signal that won't turn on a germanium diode will get through a shottky.

- 399
 

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