BCD436HP/BCD536HP: BCD436HP Discriminator Mod

[woodpecker]

I finally decided to open my 436 and get a discriminator output from it, why these outputs aren't included as standard beggars belief!

I used a 10uF tantalum cap followed by 2x 10k resistors configured as a voltage divider, the result works well with DSD and a USB soundcard.

There is a chip resistor marked 100 (10 ohms) near the audio connector on the PCB, I removed this and ran a screened cable from the components to the pad furthest away from the top of the 436. Using a stereo jack this leaves the audio output available on the tip of the jack and the discriminator on the ring.

I ran the screened wire around the screening can rather than cross what looks like a possibly sensitive area of RF/filtering components. I've attached some images.

 

[Voyager]

Nice. I often re-purpose the earphone, too. (or part of it)

Although so far I haven't found any need to tap my x36s with the proliferation of SDRs.

 

[srich10]

Nice. I often re-purpose the earphone, too. (or part of it)

Although so far I haven't found any need to tap my x36s with the proliferation of SDRs.

Is getting something like the RTL-SDR worth it? I am wanting to do something to be able to decode the DMR systems popping up here locally with ease but RTL is out of their dongles until they restock and I've always looked for how to do the discriminator tap for the 436 but haven't found diagrams until now.

 

[Voyager]

Not sure how densely populated PSL is, but if you have a lot of transmitters around the RTL may not be the best choice.

The 436 may be a better choice due to the filtering. My SDR is a higher one one so I can use it in high RF environments.

 

[srich10]

Not sure how densely populated PSL is, but if you have a lot of transmitters around the RTL may not be the best choice.

The 436 may be a better choice due to the filtering. My SDR is a higher one one so I can use it in high RF environments.

Not so much around PSL, but here in Brevard we've got a good amount of DMR sprouting up. Just didn't know which is more sensitive/liked to use; a tapped scanner or SDR dongle.

If scanner is better option, then tapping it is.

 

[larry308]

FYI the new Whistler WS1088 has a tap already installed at the factory.

Larry

 

[fourthhorseman]

FYI..... this Is a Uniden thread...


This needs to be entered into the WIKI....

Outstanding work..and admiration for getting in there
with an iron!...You are a brave soul!

Question...
Do you have,OR Could you draft up a schematic for the
tap you built?...
Yours is strikingly different from the taps I build..