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Scantenna for 2-meter

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dentman69

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Has anyone tried the scantenna for transmitting 2-meter with no scanners hooked to it ? Or antenna switch. So not to overload the scanners. Just was wondering if it would work to keep from having to put up a second tower. Thanks, Jim
 

roadranger

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Yes!

I've done it. No problem. Just use low power. By the way, I've done it also sucessfully on 1.25 m and 70 cm! (don't leave the scanners plugged in on the same cable, switch it!)
 

dentman69

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So switch the coax from the scanner to the 2 - Meter radio and I should be able to transmitt? No switches !! I can pick up alot of repeaters with the scanners and was hoping to transmitt on the 2 - meter repeaters.
 

gcgrotz

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Al42 said:
The standard coax switch has zilch isolation between radio ports, so I wouldn't use a switch.
A good quality switch will have 50-60db between ports. Check MFJ, Comet, AlphaDelta. I used one for years with 50w on 2meters on one port and a scanner on the other, no problem.
 

kb2vxa

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Hi Dent and readers,

If the SWR is low enough that you don't get power foldback on the 2M rig go for it. If it's a problem NEVER trust the protection, go QRP. Being a dipole frankly it dosen't make for any sort of gain so take that for what it's worth.

Uh oh, I just remembered something. Unless I'm wrong the Scantenna employs a small balun that may not take much power. Let's hear from you guys, no point in him frying it.

"A good quality switch will have 50-60db between ports. Check MFJ, Comet, AlphaDelta. I used one for years with 50w on 2meters on one port and a scanner on the other, no problem."

Thanks Grotz, I use an MFJ-1704 four position switch to use the Uniden scanner, IC-706Mk2G, Alinco 222MHz rig and an Azden 2M rig dedicated to packet radio on a 2M/1.25M/70cM vertical and all is well. MFJ is the cheapest and is electrically the same as the Comet, AD and the others, the best buy out of the lot.

Al, considering how many times we've told them, do you think they'd get the message there is a difference between a coax switch and a coaxial switch? (;->) Oh, does the name Dow Key come to mind? They're baaaaack.
 

roadranger

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Balun

TeRayCodA said:
Ummm...Are we talking about using a scantenna,with 75ohm coax,and a 300-75ohm balun transformer?
Sounds like a bad idea,be careful....
Yeah, I tried it, and it still works well, no matter what people say. Of course, I don't live too far from repeaters, so that may be of good help. I get good reports, still on any of the three bands (vhf/uhf). I tx through a 75 ohm jumper to a 75 ohm splitter into another 75 ohm jumper to the Scantenna with no problem at all. SWR is less than 1.5/1 on the bands.
 

kb2vxa

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Hi Ranger and all,

The SWR cannot be less than 1.5:1, your meter is out of calibration. With a perfect 75 ohm resistive load on the meter the reading should be EXACTLY 1.5:1. In any case no point splitting hairs, all that matters is the antenna system works properly within reasonable parameters.
 

gcgrotz

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kb2vxa said:
Hi Dent and readers,

"A good quality switch will have 50-60db between ports. Check MFJ, Comet, AlphaDelta. I used one for years with 50w on 2meters on one port and a scanner on the other, no problem."

Thanks Grotz, I use an MFJ-1704 four position switch to use the Uniden scanner, IC-706Mk2G, Alinco 222MHz rig and an Azden 2M rig dedicated to packet radio on a 2M/1.25M/70cM vertical and all is well. MFJ is the cheapest and is electrically the same as the Comet, AD and the others, the best buy out of the lot.

Al, considering how many times we've told them, do you think they'd get the message there is a difference between a coax switch and a coaxial switch? (;->) Oh, does the name Dow Key come to mind? They're baaaaack.
I went back and checked switch specs in the catalogs and most say 60db 1-30 Mhz and 50db at VHF/UHF. I've never actually measured one, it might be fun on a rainy day. Like you said, I think they must be made in the same factory because thay all look alike.

And speaking of coaxial relays, I still have one that was pulled out of a 125w 900 MHz transmitter, it has N connectors all around, and I can see an application for it in my future! If you can find a Dow Key at a hamfest they were great. I suspect for RX only they would work well up to UHF.
 

kb2vxa

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Hi again Grotz and all,

If I remember right the DK was good up to 1KW at 500MHz but it's been a long time. You MAY find some pretty beat up at a hamfest, "NIB" condition is very rare. I >did< say they're back, haven't checked lately but I'll bet they added to the classic line.

I found TR relays in old GE Prog Line stuff, never dug any out of Motorola Micors or GE Mastr 2s but I'm sure old commercial stuff can be a gold mine for the technically inclined. Hey, they make great repeaters, a 40W Micor is in service in Lawrenceville NJ and a 100W one made a nice packet BBS in Belmar but that went dark some years ago, it's probably still kicking around in the guy's basement.

Just a thought, commercial gear is the receiver of choice for those who provide Internet audio feeds so there must be something to it. I think the words I'm looking for are "quality" and "reliability". Same for antennas, like it says on the box "You've tried the rest, now here's the best, Al Capone's Pizza." Don't laugh, it's in Brick NJ. You'd BETTER not laugh, the guy knocking at the door has this odd bulge under his arm. (;->)
 
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