Ok i switched coax cables today i was using KMR240 now i'm using some KMR400 both from amazon. i can't tell which one is the best one is showing more signals but that may be interference and i don't know it . i'll add screenshots the first one is the KMR240 the second pic is the KMR400 which one looks to be performing the best. Thanks!
I switched coax which one is better?
- Thread starter AngWay
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mmckenna
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The KMR line is a knock off of Times Microwave LMR coax. It's probably pretty close in performance.
The Times Microwave LMR-400 will have less loss than the LMR-240, and I'd expect that to hold true for the knock off cables (within reason…).
The KMR-400 should get more signal from your antenna to your radio compared to the KMR-240. KMR-400 should "work better".
But, remember, it's not just the signal you want to listen to that will get to your receiver with less loss, so will all the interference and unwanted signals. While you are no doubt getting more of the signal you do want, you are also getting more of the signals you do not want.
What your receiver does with all that extra unwanted signal is the question.
The other question is "how does it sound to you?" That's what matters.
The Times Microwave LMR-400 will have less loss than the LMR-240, and I'd expect that to hold true for the knock off cables (within reason…).
The KMR-400 should get more signal from your antenna to your radio compared to the KMR-240. KMR-400 should "work better".
But, remember, it's not just the signal you want to listen to that will get to your receiver with less loss, so will all the interference and unwanted signals. While you are no doubt getting more of the signal you do want, you are also getting more of the signals you do not want.
What your receiver does with all that extra unwanted signal is the question.
The other question is "how does it sound to you?" That's what matters.
Uncheck both agc's, then raise your gain to 12-14
You're gonna beat your dongles to death with both those checked and an lna
You're gonna beat your dongles to death with both those checked and an lna
alright i removed the LNA but i'm still getting this weird thing that happens the signal will be doing fine then all of a sudden it will turn like this. i thought removing the LNA would fix that but it still happens.
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ok i gotcha but from those two pictures i added does the kmr400 look to be performing better. i see more signal bumps with the kmr240. oh and between the KMR and LMR there really isn't much difference ?
mmckenna
I ♥ Ø
I don't know, probably minimal.
Dimensions are probably the same, or darn close. Question would be the quality of the materials. What matters is that it's working. Coax like that won't have a lot of loss down in the HF bands.
Never seen that on sdrtrunk, are you scanning nbfm?
no it's with anything p25 nbfm dmr and it happens in every software i will be receiving the signal fine and all of a sudden it's like a overload hits it if i lower the gain to almost 0 it won't happen but thats way to low to hear anything.
This was previously discussed at:
What is wrong with my RTL-SDR Dongle?
Does anyone know what causes this. notice the bottom of the waterfall, That is normal it's showing the signal and everything is good and then about every minute or so i will see the top part of the waterfall do this. i have played around with the gain and everything else but nothing fixes it...
It was noted:
- This looks like overload from a strong nearby signal which is de-sensing the dongle
- It looks like there is a very strong signal around 152.27Mhz. Is there correlation between when this signal is active and the interference?
- This signal is certainly a candidate as pagers on that particular frequency and other frequencies are often the cause of receiver overload and intermod.
- If reducing the gain does not resolve this, you may need find the offending frequency and obtain a notch filter for it.
Got a pic of that j-pole?
rf_patriot200
Active Member
https;//messi.it Messi & Paoloni cable is Fantastic cable, FYI.
yes right here
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Do you have an old analog scanner connected to the j-pole also?
You might need too relocate the antenna, service pole with three distribution transformers just behind you, all those service lines look to run horizontally right behind your j-pole
I have severe problems with a nearby simulcast pager system around 152 MHz. I use PAR filters to dramatically improve my hobby efforts. You should note that Dale gets really busy with commercial orders. If you do not get a reply to your email, follow up after a few days. The last time I purchased his filters they were around $80.
The interference is so bad I use them in my vehicle with the scanner and another for my amateur radio. At home I use two inline, due to using an outdoor antenna to improve my RX. I also use one on my amateur radio at home.
The interference is so bad I use them in my vehicle with the scanner and another for my amateur radio. At home I use two inline, due to using an outdoor antenna to improve my RX. I also use one on my amateur radio at home.
I might suggest you are getting some out of band strong signal overloading your SDR. (LNA)
Things that will help is filtering in front of your LNA, such as an FM BC trap and band pass for your desired bands.
Post 3, yes. Play with your manual gains for best signal to noise.
I use LMR-400 only because I have 500+ feet of it, but LMR-240 in runs to 50 feet you won't see any difference.
Your J-Pole is just fine as is.
Things that will help is filtering in front of your LNA, such as an FM BC trap and band pass for your desired bands.
Post 3, yes. Play with your manual gains for best signal to noise.
I use LMR-400 only because I have 500+ feet of it, but LMR-240 in runs to 50 feet you won't see any difference.
Your J-Pole is just fine as is.
no just a rtl-sdr
what is a PAR filter? and what is dale? i have one of these Link is it the same?
If it is indeed interference, you will first need to identify what frequency is causing the interference. I would start by listening to the signal at 152.27 to see if you can identify it. Is there correlation between when this signal is active and the interference?
You have a challenging situation. You are trying to pull in weak signals in an environment that appears to have strong signals in the same area.
You have a challenging situation. You are trying to pull in weak signals in an environment that appears to have strong signals in the same area.
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