Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
How do Decibel Products low band duplexers work?
|
Ed Bathgate, RMA Repair Dept x8785
I was researching 6 meter band antennas & duplexers, and came across
Decibel Products. They have a design of a duplexer that can do a .5mhz split and its only 30" high. It uses what appears to be 6 tunable paint cans, (???!) and several sets of tuned length coax lines and several coax stubs. I have rebuilt and re tuned a hybrid ring duplexer for 2m, and old sinclair, that looked like 4 scuba tanks and a whole lot of coax. I was intrigued by their design, until I called them and got the $2300 price! Yeowza!! Ok, can I build a similar device? How can they get a small can to do 6 meters? What is inside the 'paint cans'? I already know of the heliax stub duplexer design... I know a fellow who was selling his, it does not work well according to him. I know where I can get paint cans cheap... 73 Ed N3SDO Ed Bathgate RMA Dept (724) 772-8785 pager (412) 649-6773 |
|
Tedd Doda
Hi Ed:
On Thu, 18 Mar 1999 09:13:37 -0500, Ed Bathgate, RMA Repair Dept x8785 wrote: Ok, can I build a similar device?Probably, as the inside is simple, but look around for a used one. As more and more government/business's get away from the low band, they will become easier to find. How can they get a small can to do 6 meters?Ah...the wonders of helical resonators! You have to remember that these "cans" can only be set up for NOTCHING a frequency, and not PASSING a frequency. Look at any good commercial 2 meter or UHF radio. The small square blocks near the antenna are helical resonators. What is inside the 'paint cans'?A coil of wire (the helix) and a plunger on a threaded rod which tunes the helix to the frequency of choice. I already know of the heliax stub duplexer design...Most of the heliax stubs are 1/4 wave length long, and do basically the same as a helical resonator. The shorted and opened stubs are there for usually the "C" part of the "LC" circuit (creating the "50 ohm" in/out). Tedd Doda CET packet va3sed@va3sed e-mail lazer@... |
|
John Hackman
The helical resonator/stub lowband duplexers work ... but that's about all
toggle quoted message
Show quoted text
you can say about them. It is real easy to end up with almost zero transmitter power out to the antenna and a nice, toasty warm duplexer, particularly with 250-400 watt Micor repeaters. They also provide ZERO isolation from interference and intermod-producing signals coming down the antenna line. 30-50 MHz cavities are not real common but can be found - 2 or 3 of those will make a very nice duplexer. TX-RX and Wacom also produce cavity duplexers. Or you can shop the spring garage sales for used hot water heaters and build your own! ......John WB4VVA -----Original Message-----
From: Ed Bathgate, RMA Repair Dept x8785 <ed@...> To: Repeater-builder@... <Repeater-builder@...> Date: Thursday, March 18, 1999 9:14 AM Subject: [Repeater-builder] How do Decibel Products low band duplexers work? From: "Ed Bathgate, RMA Repair Dept x8785" <ed@...> |
to navigate to use esc to dismiss