Schottkey diode/transistor opinions

[Hawkeye351]

I've been looking into these Schottkey diodes/transistors for receive/NB improvement. I've learned there's many different types of specific diodes and transistors you can use.

I've heard differing opinions on the "improvement" diodes/transistors and wanted a little more info on the different diodes/transistors you could use and which ones are recommended.

I've come up with:

Schottkey diodes
1N6263
ECG583
NTE583
BAT81
BAT85
1N5711

Transistors
2SC1674L
2SC1674K
2SC1845
BC547
2N3904
KSC1845

Frome what I've read, any of the above can be used for the receive/NB "improvement". I would like to hear others opinions on how this "improvement" mod has or has not worked for them.

My goal in this is to retain the signals without degrading sensitivity while at the same time eliminating the hash level (static level).

Example:
After receiver alignment of my personal Saturn, I have around 7 s-units of nothing but static, but late at night/early morning hours it's down to about 1.5 to 2 s-units which is acceptable to me to be at all times, lol... I detune my receive to cut all that out on my own radio, but I leave everyone else's radios alone after alignment with the signal generator.

Would the transistor and diode swap of any combination of the above parts help mine out, or would just the diode swap be my best option, or what would your recommendation be?

 

[AudioShockwav]

There's a thread about NB diodes here somewhere that has some information....
Let me look

73
Jeff

 

[AudioShockwav]

Here's the NB thread

Thread 'Cobra 29 LTD Classic Schottky Diode Mod'

Apr 19, 2018

Hey guys,
I have a Cobra 29 that I am going to use in my garage station and will be using it with an amp so I plan on lowering the dead key. I figured while I am in there, I could do the Schottky diode receive mod.
So my question is: Is this mod worth doing on this radio and would I notice a difference?
Any thoughts and replies welcome.
Thanks, 73s

• Shadetree Mechanic
• Replies: 14
• Forum: CB Radio Modifications

The subject radio was a 29 but the info is useful.
There's another one about the low noise transistor used to enhance RX a 2n2999 or something I can't remember right now.
If I find that one I will link it

73
Jeff

 

[c316buckeye]

the technician i consult is in the hospital or i could ask him the specifics. he advised against it, not because he couldn't do the mod or that the mod didn't work, but he said they "weren't good for the radio". wish i could help more. had a 94hp with them, s1 on ssb & AM, never a problem... 2980 bone stock s7+ ssb, s3 AM

 

[SuperLid]

I've been looking into these Schottkey diodes/transistors for receive/NB improvement. I've learned there's many different types of specific diodes and transistors you can use.

I've heard differing opinions on the "improvement" diodes/transistors and wanted a little more info on the different diodes/transistors you could use and which ones are recommended.

I've come up with:

Schottkey diodes
1N6263
ECG583
NTE583
BAT81
BAT85
1N5711

Transistors
2SC1674L
2SC1674K
2SC1845
BC547
2N3904
KSC1845

Frome what I've read, any of the above can be used for the receive/NB "improvement". I would like to hear others opinions on how this "improvement" mod has or has not worked for them.

My goal in this is to retain the signals without degrading sensitivity while at the same time eliminating the hash level (static level).

Example:
After receiver alignment of my personal Saturn, I have around 7 s-units of nothing but static, but late at night/early morning hours it's down to about 1.5 to 2 s-units which is acceptable to me to be at all times, lol... I detune my receive to cut all that out on my own radio, but I leave everyone else's radios alone after alignment with the signal generator.

Would the transistor and diode swap of any combination of the above parts help mine out, or would just the diode swap be my best option, or what would your recommendation be?

It's snake oil. None of those parts will do any good, some may make things worse. When I see a shottky mod, I reverse it back to germanium. I have used MPSH10's in the RX amp stages and RX pre-amps in linyeeers with success.

 

[FlyBoy50]

I heard somewhere that germanium diodes were better than Schottkey but I'm no expert by any means.

 

[c316buckeye]

It's snake oil.

*please note the other modifications available from a certain cb sales .com

 

[Hawkeye351]

Flyboy, any specific brand/type germanium you recommend to cut back on noise floor hash level?

 

[FlyBoy50]

Flyboy, any specific brand/type germanium you recommend to cut back on noise floor hash level?

Sorry Hawkeye no I can't recommend but I was considering Shottky one time to improve my receive on my DX2547 and picked up the Germanium info in another forum but never got around to modifying the radio. You probably should ask Nomadradio or others into Modding and repair. Best of luck to you and keep us posted. I know another repairman in another forum uses the Shottky. Maybe some day if I get my unfinished projects done I might consider that DX 2547 Mod again.

 

[c316buckeye]

as for getting rid of the noise, there are a few different external NRC devices that (according to reviews) do a great job at least calming that down.

for lack of knowledge, can you do the hi-cut mod? no idea what that consists of, but lots of people love it

 

[loosecannon]

I played around with the schottkys and the 2999 transistor back when everyone else was, and while initially i thought i noticed a difference in the sound of the background static, i believe it was just a perceived change and they didn't really do anything special.
I stopped messing with them years ago.

As for the issue you are trying to correct Hawkeye, i don't think this is the road to go down.
I might be able to help but i need to know what board is in your Saturn so i can use it as the example.
is it the one with the board from the RCI2950?
LC

 

[Klondike Mike]

... I have around 7 s-units of nothing but static, but late at night/early morning hours it's down to about 1.5 to 2 s-units which is acceptable to me to be at all times,

I use Vishay BAT85S with success. They don't reduce 7 s-units of noise to zero but its operation is noticeable on the 1.5 to 2 s-unit noise levels and pulling out the weak stations.

 

[Hawkeye351]

LC,
My board is the EPT360014B.

Mike,
I may try the 85, thank you.

Not really an issue, just the hash noise level is way too high after alignment, have to either turn the needle way down (which doesn't correspond to incoming signals afterwards) or detune the receive by 6 s-units. L6 drops it a little but not much, so I have to detune L4 (up front) by 6 s-units or drop my RF gain down halfway. Right now I have it aligned to signal generator but drop my RF gain down halfway to get that hash (static) noise out.

Nearby devices:
32" HD Television about 3 foot away.
Chromecast about 3 foot away.
FNRSI 1014D oscilloscope.
Agilent spectrum analyzer.
FY6800 Signal generator.
Android phone about 8 foot away.
Laptop (hardly ever on) 8 foot away.

Router/modem (Spectrum Supplied) about 20 foot away in another room.

My AC outlet is on its own circuit in the breaker box.

All my test equipment is plugged into a 100,000 jul line conditioner through an industrial style power strip.

My breaker box is grounded to a ground rod in the ground.

Not sure if they hooked up the neutral wire on any of the 110v outlets though.

I usually align other people's receive by the signal generator and let it go, no one has complained about too much receive on their end, they say the receive looks about right. I have cracked a couple down before and forgot to turn them back up before giving them back to the owners, only to have them ask me to bring the receive back up, lol...

 

[FlyBoy50]

I've been using a West Mountain Radio Processor that I'm happy with for noise reduction but they aren't cheap. But then again nothing about this hobby is Cheap ! LOL

 

[Cable Guy]

A noisy RF amp transistor or mixer transistor in the front end can cause lots of hash and distortion. I have seen it a few times. But 7 units? With the radio unplugged from the antenna at the back of the radio, do you still get the hash?

Edit to add, unless you are replacing a faulty diode or transistor, not much to gain with the other mods. You could try a transistor with a lower noise floor but 7 units sounds like a noisy environment or transistor.