Discriminator Tap?

[zonian149]

I have an old Pro-2032 that I want to add a discriminator tap to, but the directions state to use a 2.2 nf capacitor and 10 k resistor. I have neither of these without a trip to Radio Shack which I really don't want to do and I was wondering if this is absolutely necessary. I imagine it is since the directions say to do it. I have a Pro-2045 with a discriminator tap in it and there are no capacitors or resistors on in or in the directions to do it. Any enlightnment would really be appreciated.--Gary

 

[crippledchicken]

I would for sure, use the components, and correct values or you may ruin your scanner!

 

[fmon]

I set a tap in three Radio Shack Scanners 2046, 2048 and 2052 using the 10k only.

 

[tunnelmot]

yeah, me too...

Funny you should mention this.

I went to radio shack today and could not find the correct value cap. (Or maybe I'm no good at converting cap values)

Recently I did a bc760 and the instructions only called for the 10k, but this (the 2032 mod)specifies the cap, so I will continue my hunt.

My 760 has crappy 800 recieve, even after I adjusted all the pots. I get decent decodes on utrunker, so I blew the dust off my 2032 in hopes of an even better cc decode. (along w/my gain 800 ant.)

If your local rat shack has the same parts drawers as mine, probably no luck getting the right value.

Rich

 

[tunnelmot]

quick update-
Found Bill Cheek's "white paper" by Google. Hope this helps you, I will hit the 'Shack tommorrow and go through the drawers again.

Here's what it said:
-has to be a tantalum cap
-any value between 1.0uf to 10uf, but it deems 2.2uf to 4.7uf is preferred.
-the positive leg goes to the tap side

I will try to get to it this weekend, and see what I get.

Rich

 

[k4gps]

The reason some mods show a resistor and some show a cap and resistor, and possibly others just show a cap is because these are all different mods :lol:

All of the radios mentioned are different and so are their designs. There is more than one way to skin a cat also, one mod may be tapped off at one point while another mod is tapped off at another and that goes for several radios SO the need for either a cap, resistor, or cap and resistor.

Some mods may do better than others also, depending on how it's done. But anyhow, to the original question do the mod as stated. ALSO if you are new to this research the mod as well as you can. Make sure you read all that you can about it and that they all say the same thing. There are a lot of "arm chair engineers" out there and someone can steer you the wrong way and you are out of a radio.

 

[fmon]

You know folks,

I have a Brett Miller slicer so it has the cap internal in the discriminator.

My 10k is used to run UniTrunker for isolation from the sound card.

 

[tunnelmot]

ok, for the unitrunker through the sound card, the cap was not needed. I was going nuts with the scope. After triple checking everything to no avail, I started clipping, figuring I would start fresh another day. As soon as I clipped to cap (ground), ut spring to life.

So as, stated above, depends on whether you're slicin' or not.

To the OP, if you PM me your address, I'll send you some 10k resistors free in the mail. plenty laying around.

Rich

 

[zonian149]

I will like to publicly thank tunnelmot (Rich) for him sending me a resistor and cap to do my discriminator tap on my Pro-2032 without my asking for them and free of charge. I am really impressed how nice of a thing that was for him to do. Thanks again Rich.--Gary

 

[K8TEK]

Funny you should mention this.

I went to radio shack today and could not find the correct value cap. (Or maybe I'm no good at converting cap values)

Recently I did a bc760 and the instructions only called for the 10k, but this (the 2032 mod)specifies the cap, so I will continue my hunt.

My 760 has crappy 800 recieve, even after I adjusted all the pots. I get decent decodes on utrunker, so I blew the dust off my 2032 in hopes of an even better cc decode. (along w/my gain 800 ant.)

If your local rat shack has the same parts drawers as mine, probably no luck getting the right value.

Rich

You need a 2.2nf, or 2200pf, or .0022µf. Capacitors of that value are normally presented in the picofarad unit, but RadioShack uses microfarad for some reason. You need this to filter out the 455khz component of the IF. The resistor prevents the IF from being loaded and burning it out. Yes, you need at least the resistor, if it calls for a capacitor you need that too.