Build Duplex Allstar Node with 888s and UV-82

In my last article I wrote about using a BF 888s short board HT for an Allstar simplex portable node. I quickly added another HT to it so I could use it duplex. Anyone who has used a 2 way crossband or a simplex node knows, it’s easy to get locked out of the conversation when you have to wait for the repeater to drop so you can get in. I ALWAYS use 1-way crossband for that reason.

So here is how I converted my simplex node to duplex, kept it in-band and did not have to use duplexors. Yeah, you heard me. IN BAND and NO DUPLEXERS.

First the hardware:

Uv82-for-Allstar-Node

I used a UV82 I had lying around. I couldn’t find connection points anywhere on the net so I did my usual hillbilly detective work. Poke it till it smokes or works. (Actually, I did use a scope)

I only found tx connections, because I only need this radio to tx. I went into the 888s cable and snipped the tx lines and ran new ones to the UV82.

So when I was done, I had COS, RCV AUD and GND from the BF 888s. I then had PTT, TX AUD and GND from the UV82.

I connected these 2 cables into 1 DB9 that connects to the RA-35 USB interface. Each wire to it’s appropriate pin in the DB9. The grounds are tied together.

BF-888s-and-UV82-duplex-allstar-node2

When I first hooked everything up, I had real trouble with rf. I had the 82 on VHF XMT and the 888s on UHF RCV. Since my box is not properly shielded, there was not a whole lot I could do without a total re-design.

I talked to a buddy and he told me about “Link to Link = yes”
Yeah, I remember that and didn’t know what the hell it meant.

Well here is what it means. ALLSTAR ROCKS! When you enable this feature and set Duplex to 1, The TX radio does NOT tx when the receiver is active. That means it only repeats traffic from the internet side. You don’t have to worry about the TX getting back into your receiver. With it in this configuration, I was able to put BOTH radios on UHF and not need duplexors.

For some reason the VHF freq was causing problems with the Pi. UHF never did in simplex mode, so when I went to all UHF and a 10 Meg split, BOOM. Problem solved.

BF-888s-and-UV82-duplex-allstar-node

Hope this helps,

73
WB4ULK