Uniden 510xl rx mods?

[Uncle Ronnie 336]

Seeking info on shottky diode and other rx mods. I'm playing with one, did the mosfet mod already.

D4 is the anl diode?

 

[sp5it]

You can't make a silk purse out of a sow's ear.
Only reasonable improvement would be repace FT1 with crystal one, but filter itself is 2x more expensive than this radio

 

[Uncle Ronnie 336]

I got 3 of these (phillipine) going to some local jeeper 4x4 Bros. So if you refer to the thread I put up about how I rebuilt the final and driver of a Kraco kcb4007 after naysayers said it couldn't be fixed to talk right, you will see me disregarding comments like this.....

I always will slap lipstick on a pig and name her Betty.

 

[Handy Andy]

The 510XL is not a "perfect radio" to do a receive mod on...

So you have the Discrete one or the SMD one?

The SMD one is not a good candidate.

The Discrete one is great - for it has several "RX tweaks" in it you can do to help but it will not be a selective stellar performer able to pick out your friends from all the engine noise the vehicle will produce - it just knocks everything down aggressively - the SMD ones did away with any variables to help find the threshold of noise to signal you could use to help - the older Discrete chassis is the best one to work with.

The older one used the TDA1220 AM/FM Radio on a chip - if you have that board, there's hope.
Similar to the 510e only without the Electret condensor mic element; attached is the 510 SMD version with the ANL magnified to show how the ANL and Detector side worked.

 

[Uncle Ronnie 336]

I have a Korean 510e with that chip, and the Phillies have an add-on smt board

 

[Handy Andy]

Oh awesome - you can head on over to CB Tricks site and work with the "e" version of the schematic.

VR4 is the RX sensitivity...
L11 and L3 work with that TDA1220 chip
​

http://www.cbtricks.com/radios/uniden/pro_510e/graphics/uniden_pro_510e_sm.pdf

The 520e side of this uses that same board but added RF gain - also has some info on it too to help

 

[9C1Driver]

I got 3 of these (phillipine) going to some local jeeper 4x4 Bros. So if you refer to the thread I put up about how I rebuilt the final and driver of a Kraco kcb4007 after naysayers said it couldn't be fixed to talk right, you will see me disregarding comments like this.....

I always will slap lipstick on a pig and name her Betty.

The thing about it is that naysayer as you put it has probably forgotten more about radio mods and repair then most of us even know. The 510 and 520 radio's for the money are great little purpose built radio's. They will never do things a 300 dollar radio can but that's ok, they were never intended to do so in the first place.

 

[Uncle Ronnie 336]

So maybe detouring a little bit but looking at the board there's an area around a spot marked Q7 which looks like a pretty convenient spot to build a microphone preamp.....

 

[Uncle Ronnie 336]

Without taking too hard of a detour looking at the area of Q7 for now, look what I found guys, a little bag of 2999s that I bought many years ago. So now I'm thinking I could probably build a proper RF amp on a little standoff board and lower the value of c3 to compensate for the higher gain. It's not like these Philippine models don't already have to stand off boards right on there.... Yes it's a lot of work for a small cheapo radio but I kind of like things that come out the other end as Frankenstein.

 

[Handy Andy]

Board shots of a 510XL...

Tried to get the 4 corners well enough...

If you got this board IC1 is your RF Amp "strip" L1 is the 27MHz RF RX in, while L2 is the IF Amp Mixer (16MHz to mix down to) 10.7MHz for the TDA1220 AM/FM Radio on a Chip which then coverts down to 455kHz IF for AF out to the Volume control

The Varactor is 1SV73 - 18pF 1V - 1MHz - then drops to ~8pF at 3V at 1MHz