-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
pdc 1089 low pass filter
- Thread starter towernewbie
- Start date
It should be the last bump in your feedline before the antenna, that is to say that it goes last inline before you coax leaves the shack.
Actually it should be right after the radio or the amplifier if you use one.Use as short of a cable between the two as you can.
If you do that the meter (if used) will read the input SWR of the low pass filter and not the antenna.
Yes, it will. But that filter should contribute very little to the SWR/impedance of what follows it, and shouldn't make any difference anyway. If it does, it's improperly designed, or there's a problem with something on the 'front side' of that filter.
A filter should be placed where it will do the most good. Since whatever's on the front side of that filter is 'dirty' and whatever's behind that filter is 'clean', the closer to the thing that's 'dirty', the better. Right? Less radiation of the unwanted stuff.
That filter (low pass type) can also be a very rough means of finding what's doing the 'dirty' stuff. Placed right after the transmitter and no change in output, then probably something after the transmitter is the culprit (if there's anything 'after' the transmitter, such as an amplifier?). If placed after than amplifier and things 'clean' up, guess what the probable culprit is. If it doesn't 'clean' anything up, beat it to death with a hammer, it don't work anyway. And all that assumes that the problem is with your transmitter/amplifier/whatever, not a problem with the receiving device. That's not a definitive way of testing or checking, just a very rough one, and there's a lot of "if/and/buts" in there... whooopy.
- 'Doc
Don't take the thingy about the hammer too literally. It just makes you feel better about guessing wrong.
A filter should be placed where it will do the most good. Since whatever's on the front side of that filter is 'dirty' and whatever's behind that filter is 'clean', the closer to the thing that's 'dirty', the better. Right? Less radiation of the unwanted stuff.
That filter (low pass type) can also be a very rough means of finding what's doing the 'dirty' stuff. Placed right after the transmitter and no change in output, then probably something after the transmitter is the culprit (if there's anything 'after' the transmitter, such as an amplifier?). If placed after than amplifier and things 'clean' up, guess what the probable culprit is. If it doesn't 'clean' anything up, beat it to death with a hammer, it don't work anyway. And all that assumes that the problem is with your transmitter/amplifier/whatever, not a problem with the receiving device. That's not a definitive way of testing or checking, just a very rough one, and there's a lot of "if/and/buts" in there... whooopy.
- 'Doc
Don't take the thingy about the hammer too literally. It just makes you feel better about guessing wrong.
I would place it at the ouput of the radio, using a short piece of coax or a right-angle connector. Some have used a second one near the antenna. As with any device you will have insertion loss, but the 1089 has a low insertion loss at 27MHz. This unit is bilateral meaning you cannot hook it up incorrectly. If you have a slightly higher SWR I would recommend drilling out the rivets, scraping the powder coating around the screw holes, working for PDC (years ago) I found this helped with the insertion loss.
why would you buy a filter capable of 1kw and not put it behind the amp>? perhaps you have lots of money to waste?
Did'nt think so.
For what it's worth it really would'nt matter about putting the filter after the final output meter unless you did'nt really want to see how much harmonics you were trapping.
why would you buy a filter capable of 1kw and not put it behind the amp>? perhaps you have lots of money to waste?
Did'nt think so.
For what it's worth it really would'nt matter about putting the filter after the final output meter unless you did'nt really want to see how much harmonics you were trapping.
Whats wrong with you, if you trap the harmonics evenone will think you are a mud duck, You got to bleed em out!
I put it between the amp and meter. Never dawned on me to put it after the meter.
radio - amp - lpf - meter - antenna
radio - amp - lpf - meter - antenna
why would you buy a filter capable of 1kw and not put it behind the amp>? perhaps you have lots of money to waste?
Did'nt think so.
For what it's worth it really would'nt matter about putting the filter after the final output meter unless you did'nt really want to see how much harmonics you were trapping.
#11
Lazybones1222
DX is my thing
EXTRA
Join Date: Apr 2005
Location: Tampa Bay Florida
Posts: 682
I put it between the amp and meter. Never dawned on me to put it after the meter.
radio - amp - lpf - meter - antenna
"I put it between the amp and meter."
that's where it belongs.
__________________
292 Radio Shop / FireCommunications Network
Technicians Exchange Forum / ASH
Then we are in agreement>?
ok dumb question can someone layout how all the jumpers are ran to each piece
for example from rafio<tx side of amp<from rx side of amp to in of lpf?
for example from rafio<tx side of amp<from rx side of amp to in of lpf?