Does the Schottky Diode Mod and 2999 Work?

[Bill94]

Hello, does anybody know if the schottky diode and Transistor swap actually made any difference to CB radios? Actually more like Galaxy dx94hp export radios with the 6900 board?
This may be in the wrong forum spot, and i apologise if it is.
What i am looking for is a REAL comparison and SINAD report and technical look, instead of the "ear listening to static levels" test on "various Cobra Radios".
Has anybody proved that this modification has worked "technically"?
All thoughts are appreciated as id like to know if this would be good for my $500 radio.
Many Thanks
Will

 

[Robb]

Schottky = yes.
2999e = no.

There has been some discussion of the 2sc1730 used for the 2sc1674 swap, but no info yet if it was a straight-across swap or if the circuit need modding first.

 

[loosecannon]

try doing some searching on this forum on this subject.

i know there was a thread a while back where someone was doing the type of tests you are referring to, but cant remember anything else about it.

i do remember that he found that there was a slight improvement with the diodes.
LC

 

[Z-MAN 369]

I did this mod on my lil 959, not a dramatic night & day contrast but much, much better RX. Anything to get rid of white noise or annoying hiss we all listen to is an improvement. Seems like everyday i hear my locals say "what a high noise level today" i look down and i have a 1-3db signal.....I bought the lil kit from Dodgem's mod site for $12 i think. I know there's one more lil transistor i could swap but ive read it would blow the front end out if someone was in my driveway, lol. Use a hemostat though to hold em.

 

[The Jerk]

I think you will find it depends on the radio...some it makes a noticeable difference, others are pretty good from the factory and it is almost a pointless mod.

Sent from my SAMSUNG-SM-G730A using Tapatalk

 

[KG6YGE]

I did the 2999(D) mod on the Uniden 858 chasis (Radio Shack) and it certainly improved the small signal digout on SSB, almost brought it to the level of listening performance of the adjacent ICOM 745 (858 had been aligned previous), using a 1/2 wave dipole inverted V resonant at ch 38.

On AM, no change to report for the 858, but AM is too noisy to characterize. I didn't use the 2999E mode FETl as the gain is higher than I needed.

I should go back and perform the diode swap.

 

[CTStallion]

On the NEWER Ranger/Galaxy boards, doesn't seem to make a bit of difference.

However, on the OLDER rigs like:

HR-2600's, 2510's, & Lincolns; 5 pin Cobra 148 GTL's, TR-296's, & Grant XL's; SS-3900's; Cobra 29 LTD's: YES, the 2SC2999's DO make a difference on receive. I have found them to be much quieter and improved front end gain.

Diode mods for the NB circuits don't seem to make much difference on ANY radio, but the diode mods for the AM product detectors DO seem to help with ALL the rigs, whether new or old.

At least this has been my experience. I haven't tried them on any other platforms but what I listed above. The only radios I didn't see much improvement on were:

Galaxy DX-94HP
Galaxy DX-98VHP
RCI-3900HP

But I'm pretty sure that this is due to the fact that the aforementioned new transceivers already come from the factory with a high gain / low noise RX amplifier ALREADY installed in them.

The rest of the radios I've tried them on had (as stated) noticeable improvements.