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>600MHz LTE filters/LPF-600 substitutes?

21K views 83 replies 20 participants last post by  JHBrandt 
#1 ·
I install antennas in areas where I have verified that 600MHz LTE signals are now present. I've been using Linear LPF-600s (the only >600MHz filters I could find) and they seem to work fine. However, I went to order more, found they were out of stock all over and the one place I ordered from e-mailed me back and told me they were on backorder with Linear until November. I checked Tin Lee and their filters start at $150. Any other options?
 
#3 ·
Since 600Mhz filters can significantly atrenuate channels 35 and 36, a better solution needs to be marketed.
My market has a channel 36 station that is revoved with a 600Mhz low pass so the Channel Master is still the best solution here.
And my service monitor sees nothing in the 600Mhz
spectrum strong enough to cause any issue.
 
#12 ·
Since 600Mhz filters can significantly atrenuate channels 35 and 36, a better solution needs to be marketed.
My market has a channel 36 station that is revoved with a 600Mhz low pass so the Channel Master is still the best solution here.
And my service monitor sees nothing in the 600Mhz
spectrum strong enough to cause any issue.
Jan Jenca made my filter 470-608Mhz. It passes Channel 36 fine, I have a very strong RF36(WUNE). Hope Channel Master is making something similar at a good price point.




 
#4 ·
I checked Tin Lee and their filters start at $150. Any other options?
There was a company East of Syracuse NY (Communications & Engineering) but they unfortunately went out of business. They were partners (of sorts) with Tin Lee, but their traps & filters were less expensive.
It's too bad they still aren't around, they were my go-to source from single channel traps. :(
 
#6 · (Edited)
Any idea on shipping??

That $50 notch trap bandwidth is way too wide. 25megs doesn't cut it with even a one channel removed adjacent channel. And that's at -5db down instead of the typical -3db.
 
#9 ·
Any idea on shipping??

That $50 notch trap bandwidth is way too wide. 25megs doesn't cut it with even a one channel removed adjacent channel. And that's at -5db down instead of the typical -3db.
You'd have to contact them and see if they can make what you want to your specification. They customized a band pass filter for me for $5 above the list price on eBay.
 
#13 ·
The need for this may be growing. T-Mobile lit up a cell tower near my home at 11 AM today, and RF 39 and 40 jumped to a signal strength of nearly 100 on my HDHR, same as the full-power stations on RF 29-36.

It's not causing me any grief, but I wonder about others who may have weaker stations at RF 36 and are also very near 600 MHz-band cell towers.
 
#14 ·
The HDHR shows 100% Signal Strength at 0 dBmV or -48.75 dBm and greater. The TV dynamic range runs up to around -8 dBm or 40 dB stronger. It's too bad they chose to set 100% to 0 dBmV because it's not helpful in seeing how strong a signal really is. In many cases 100% on the HDHR is no problem at all for the TV tuner.
 
#15 ·
Yeah I kind of figured: even with all my strongest stations at 100, I could still increase amplification quite a bit before I saw any signs of overload. So the HDHR doesn't really tell you how close you are to the point of overload. The best I could do was set my amplification so that a few strong stations were slightly under 100, and as long as the weaker stations were still OK I figured I was fine.

I just don't recall ever seeing a cell tower signal that strong before, and I figure some folks are even closer to a tower than I am, so they might have a problem (especially if they're in a fringe TV reception area).

Strangely, that strong cell tower signal was on for just about exactly 24 hours, then today it switched off again. So it must have been a test. But I suppose eventually it will switch back on permanently.
 
#16 ·
Any updates on this? I have a tuner that's getting blasted by B71 now in the Seattle area and the 700MHz version is no longer good enough.

I checked CM's website and the CM-3201 now shows 600-2000 as the band-stop. But that might not be good for 36 (or even 35) if they are being literal about 600.

Does anyone have the (apparently) new version? I have ordered it with a note to confirm it's been changed. CM should surely know not to heavily filter 36... right? And Seattle has an RF36. So does LA down here at my primary QTH, but B71 is pitiful where I live in OC rn, so it's not a problem, yet...

The trouble is B71's DL's are right next to RF 37 and the uploads are next to where B12's are. It would be a lot easier for us to filter it, if it was the other way around (as uplink signals aren't constant like downlink).

Thanks,
 
#17 ·
I received this response from CM just now. I think it's a bit off... but I ordered the CM3201 and will test it on 35 and 36 here to see how much it degrades those two here before I take it to WA:

Mike,

I spoke with engineering further on your request here and I do apologize I was incorrect. The LTE filter you purchased [CM-3201] beings rolling off at 609Mhz and will include up to channel 36. It will block the entire T-mobile spectrum and the start of the B71 band at greater than 40db down. I hope that helps you further, if you have additional questions please let us know!

Ann
Customer Experience Manager
support@channelmaster.com
 
#23 ·
Channel Master Blog post regarding this filter

This is part of the Engineering spec sheet that CM support emailed to me:

...

I measured the attenuation of the new CM-3201. The insertion loss for 36 is about 3.3 dB for my sample:

...
Thanks as always for your insight Rabbit73!

I happened to find this week that Channel Master's website has a Blog page, and the most recent posting is about their revamped LTE filter.
Noted just like you found is that it only slightly affects RF36, but squelches cell phone signals further up in the 600 MHz range:

https://www.channelmaster.com/lte-filters-for-tv-antennas-what-you-need-to-know-a/962.htm

Cheers! ~~ Statmanmi
 
#20 ·
I have a Kliztech amp that has the outdoor covering and the Channel Master LTE filter is too wide to fit the F connector . The input connector is too close to the side wall of the cover . Probably a silly question but will the Channel Master filter out cell signals if I reverse connect it directly to my antenna then have the the RG cable run down to the pre amp ?
 
#21 · (Edited)
I think that would be OK, but the filter will be exposed to weather. No need to reverse it, it probably isn't symmetrical since it is a lowpass filter. But, for comparison you can try it reversed first.

Normal:
Antenna > short coax jumper > Filter Antenna Input ----- Filter to Amp Output > F-81 Adapter > short coax jumper > Preamp Input

Reversed:
Antenna > Filter to Amp Output ----- Filter Antenna Input > short coax jumper > Preamp Input

An alternative would be a larger enclosure for the preamp and the filter.

Please let us know if the filter helps you.
 
#26 ·
Out of curiosity, IF there actually is interference from on of these more than annoying 'toy phone towers', just how does one know, other than guessing or trying one out?
It seems that these are being purchased on the assumption it will solve reception problems known or unknown may or may not have.
(Especially over at Amazon. :rolleyes: )
 
#29 · (Edited)
Good question. If you don't have cellular interference, you really shouldn't use an LTE filter because its insertion loss in the passband might make your weaker signals even weaker.

As JHBrandt pointed out, you would need a spectrum analyzer to see the cellular/LTE signals just above UHF channel 36.

An inexpensive spectrum analyzer can be made using an RTL-SDT.COM V3 dongle ($25) and free open-source DIY RTLSDR Scanner software from GitHub.
Buy RTL-SDR Dongles (RTL2832U)

Cable Technology Electronic device Electronics accessory Font


Text Blue Plot Line Font


Text Blue Line Font Plot


If you find it difficult to assemble the DIY software (I did), you can use free ready-to-use SDR# (SDRsharp) software which will show about 2 MHz at a time. Just tune above 608 MHz until you run into the cellular signals.

Text Technology Electronic device Line Font


My amateur video:

2020-11-28 21-36-14 Cellular at 622.mp4

download
https://www.dropbox.com/s/u2j6fubcvj07zw4/2020-11-28 21-36-14 Cellular at 622.mp4?dl=1

I use VLC Media Player

You could also use a TinySA Spectrum Analyzer, but they have poor resolution at LTE frequencies.

The deluxe option is an Airspy R2 SDR ($200) with Spectrum Spy software:

Blue Text Font Technology Oscilloscope


2020-11-28 22-51-06 UHF and 622 Cellular.mp4

download
https://www.dropbox.com/s/wn8h3zljsrhlkjj/2020-11-28 22-51-06 UHF and 622 Cellular.mp4?dl=1

Font Technology Screenshot Parallel


2020-11-28 23-01-18 UHF TV and above.mp4

download
https://www.dropbox.com/s/ahezmu37p00wgtx/2020-11-28 23-01-18 UHF TV and above.mp4?dl=1

I don't have LTE interference.
 
#27 ·
My guess is that only a few unlucky souls have the misfortune to be both very close to a band-71 LTE tower and also far from their TV towers. Those are the only ones likely to need one of these for reception issues: they need a low-noise amp to receive TV, but then the LTE signals get so strong they cause IM distortion in their tuners.

Without a spectrum analyzer it would be hard to know if you fall in that rather small camp. There are other uses for LTE filters; e.g., clearing bandwidth above RF 36 for your own in-house signals - but it's definitely a niche product.

If sales of these are above the niche level, I'd guess that some folks are buying them in hopes of improving reception, then discovering they don't really help. But at $9-$19, it's hardly worth the hassle to return....
 
#30 ·
My guess is that only a few unlucky souls have the misfortune to be both very close to a band-71 LTE tower and also far from their TV towers.
I would say it's more than just a few, especially ones in a city (or 1st ring surburbs) that have a 2nd market close by (less than 50 or so miles away).
 
#31 · (Edited)
Could be. Of course in that situation you may well have another problem: the amp you need for the 50-mile signals may make your local TV signals too strong, causing the same problem (but without an easy in-line filter solution).

The way around that (assuming the local and 50-mile signals lie in different directions) would be to use two antennas with a preamp on the 50-mile one. Combining the two antennas without interference is now possible, but it does require a rather specialized piece of equipment: a programmable filter (which will also take care of the LTE issue). It's rather more expensive than one of these inline LTE filters though.

Here's a thread discussing the one programmable filter I know about: Avant X New way to combine up to 4 different antenna...
 
#32 ·
Could be. Of course in that situation you may well have another problem: the amp you need for the 50-mile signals may make your local TV signals too strong, causing the same problem (but without an easy in-line filter solution).
The way around that (assuming the local and 50-mile signals lie in different directions) would be to use two antennas with a preamp on the 50-mile one.
Then add, the cancellation effect of the 'locals' due to the poor F/B ratio of the antenna used for the distant signals coupled to the use of a lower gain antenna (since higher gain isn't needed) for those locals .
BUT, running both antennas thru the DA, helps, but it adds excessive crap from the 'locals' especially in the VHF high band with 1 station in a very poor location leasing space on a 3rd rate tower (left over from the 70's or earlier).

Now that would really suck. :mad:
 
#41 ·
^ That's not correct whomever came up with that chart; ^
What happened to ch. 2-13 in all cases? Nothing, those are still there.
Then there was ch. 2-83 that went away in 1983, that wasen't listed at all (in spite of 70 & up limited use).
 
#42 ·
After a little research, I see there appears to be three types of these LTE filters (depending on how old (or new) the design is;
800MHz, 695MHz & 600MHz
at least ones listed in Amazon (chosen only for the convenience of having different models listed in one web site vs doing a extended search).

Most seem to have the cutoff listed, but some one has to look for it. And for Joe SixPack, that would//will be overlooked very easily. ;)
 
#45 · (Edited)
After a little research, I see there appears to be three types of these LTE filters (depending on how old (or new) the design is;
800MHz, 695MHz & 600MHz
at least ones listed in Amazon (chosen only for the convenience of having different models listed in one web site vs doing a extended search).

Most seem to have the cutoff listed, but some one has to look for it. And for Joe SixPack, that would//will be overlooked very easily. ;)
Yes you are correct there are three types of LTE filters with the latest ones are designed for the recent repack to pass channels 5-35 (5-600MHz).
Only three LTE filters from Channel Master CM3201 (5-599MHz - actual 5-629MHz), Ness Electronics SB5G (5-608MHz - actual 5-620MHz) and the Jasco Phillips
SDW1520/27 (5-608MHz) that can be found locally that suit the bill ! You can get the Phillips LTE filter on Amazon if you live in the US, but they won't ship to Canada.
The Channel Master and Ness Electronics are the same filter that is made in Taiwan. I am trying to find the manufacturer in Taiwan that makes it for them so I can get them cheaper, Channel Master's shipping cost of $12.50usd per filter to Canada is ridiculously expensive if I want to order more than one.
 
#47 ·
Just noticed this thread and thought I would share a friend of mine's experience about 3 months ago,. He is in the suburbs of KCMO, 12 to 18 miles from the broadcast towers, has an attic antenna with no amplification and wasn't having any problems. Suddenly broadcast ch 29, 560-566MHz, had major pixeling. Other channels were ok. He is not the greatest at describing symptoms, but I gathered between the lines that it was fairly constant. He actually finally got ahold of the broadcast engineer who maintains the RF for that station. The BE said that the new 5G transmissions are splattering interference out of their legal bandwidth around here. He has reported this to the FCC. He recommended the CM-3201, which has solved the problem.
I am skeptical about this actually being co-channel interference at 560MHz, which wouldn't be eliminated by the CM-3201. But something having to do with LTE seemed to be happening. I live in the city and picked up a CM filter to play with. Intermittent problems are not being caused by LTE at my house.
These signals are broad enough that I can see them on my Sadelco Display Max 800. What I am seeing at 600MHz is very low and intermittent. What I see at 700MHz is much higher and more constant. We do have an active channel on 36 and I see only about 2.5 dB loss with the 3201 at that frequency, which seems to be the insertion loss for the whole passband. The filter also seems to work in either direction. I am surprised that CM still is using the same 3201 model number for this new filter.
 
#48 · (Edited)
Just noticed this thread and thought I would share a friend of mine's experience about 3 months ago,. He is in the suburbs of KCMO, 12 to 18 miles from the broadcast towers, has an attic antenna with no amplification and wasn't having any problems. Suddenly broadcast ch 29, 560-566MHz, had major pixeling. Other channels were ok. He is not the greatest at describing symptoms, but I gathered between the lines that it was fairly constant. He actually finally got ahold of the broadcast engineer who maintains the RF for that station. The BE said that the new 5G transmissions are splattering interference out of their legal bandwidth around here. He has reported this to the FCC. He recommended the CM-3201, which has solved the problem.
I am skeptical about this actually being co-channel interference at 560MHz, which wouldn't be eliminated by the CM-3201. But something having to do with LTE seemed to be happening. I live in the city and picked up a CM filter to play with. Intermittent problems are not being caused by LTE at my house.
These signals are broad enough that I can see them on my Sadelco Display Max 800. What I am seeing at 600MHz is very low and intermittent. What I see at 700MHz is much higher and more constant. We do have an active channel on 36 and I see only about 2.5 dB loss with the 3201 at that frequency, which seems to be the insertion loss for the whole passband. The filter also seems to work in either direction. I am surprised that CM still is using the same 3201 model number for this new filter.
Sometimes when you witness them installing the darn things is the moment you start getting pixelation ...it can only be a given ! ...LoL
From what I understand that these small cell eNodes can pass both 4G LTE and 5G is the reason why they are installing thousands upon thousands of them ! In just one block there can be upwards of 5-10 small cell eNodeB antennas installed on lamp and hydro posts.

Here you see just Telus's small cells alone in the same area
3065860


...and now on top of Rogers' small cells and Bell's (not shown) and you got like a nightmare scenario for us OTA users when one is less than 30-50 feet from your antenna !
3065861
 
#55 · (Edited)
A little follow up after installing the Channel Master CM-3201 (5-599MHz) LTE filter to the input of my CM-3410 distribution amp. To my disappointment it did not fix the problem. :(
I was able to receive all these channels for over 11 years with my distribution amp powered on prior to Telus installing a small cell antenna 40 feet from my antenna in mid October:
After I noticed Telus installing a small cell 40ft from my antenna I go these results.

With CM-3410 distribution amp power turned OFF
Virtual Real Frequency CallSign Network
2.1 19 503MHz CBFT-DT CBC Good
3.1 20 509MHz WCAX-DT CBS Good, Occasional No Signal
5.1 14 473MHz WPTZ-DT NBC Good, Occasional No Signal
6.1 21 515MHz CBMT-DT CBC Good
10.1 11 201MHz CFTM-DT TVA Good
12.1 12 207MHz CFCF-DT CTV Good
15.1 15 479MHz CKMI-DT Global Good
17.1 26 545MHz CIVM-DT Télé-Québec Good
22.1 7 177MHz WVNY-DT ABC Occasional PSID No Signal
29.1 29 563MHz CFTU-DT Canal Savoir Good Occasional, Pixelation
31.1 14 473MHz WNNE-DT The CW Good, Occasional No Signal
33.1 32 581MHz WETK-DT PBS No Signal, Occasional PSID, Good Occasional
35.1 35 599MHz CFJP-DT Noovo No Signal
44.1 16 485MHz WFFF-DT FOX No Signal
47.1 31 575MHz CFHD-DT ICI No Signal
57.1 36 605MHz WCFE-DT PBS No Signal
62.1 17 491MHz CJNT-DT CityTV No Signal

With CM-3410 distribution amp power turned ON and LTE filter installed
Virtual Real Frequency CallSign Network
2.1 19 503MHz CBFT-DT CBC Good
3.1 20 509MHz WCAX-DT CBS Minor pixelation
5.1 14 473MHz WPTZ-DT NBC Good
6.1 21 515MHz CBMT-DT CBC Minor pixelation
10.1 11 201MHz CFTM-DT TVA Minor pixealation
12.1 12 207MHz CFCF-DT CTV Good
15.1 15 479MHz CKMI-DT Global Minor Pixelation
17.1 26 545MHz CIVM-DT Télé-Québec Minor Pixelation
22.1 7 177MHz WVNY-DT ABC No Signal
29.1 29 563MHz CFTU-DT Canal Savoir Minor pixelation
31.1 14 473MHz WNNE-DT The CW Good
33.1 32 581MHz WETK-DT PBS Occasional PSID heavy pixelation
35.1 35 599MHz CFJP-DT Noovo No Signal
44.1 16 485MHz WFFF-DT FOX Occasional PSID No Signal
47.1 31 575MHz CFHD-DT ICI heavy pixelation
57.1 36 605MHz WCFE-DT PBS No Signal
62.1 17 491MHz CJNT-DT CityTV Occasional PSID heavy pixelation

I am stumped to what is really causing this now and can only come up with two other possibilities. I thought that since channels 35.1 and 57.1 are in the 600MHz range their signals would be the ones to suffer most with no signal with either the amp on ON or OFF.
1. Out of band interference from Telus's LTE antenna due to it's close proximity to my antenna
2. My CM-3410 distribution amp is faulty. Checked power adapter voltage and it is all good, green LED light up

Any more suggestions I should try ?
 
#70 ·
A little follow up after installing the LTE filter to the input of my CM-3410 distribution amp. To my disappointment it did not fix the problem....With CM-3410 distribution amp power turned OFF.....
I'm curious about your problem and would like to ask a few more questions.

Did you just turn off the power to the 3410 and leave it in line, or did you remove it completely? I would think that if you turned off the power but left it in line, it would act as an attenuator.

I'm wondering about the strength of the TV signals at your location. Would you be willing to show us a signal report from rabbitears.info?

What antenna are you using and where is it located?

Is your antenna aimed at Mt. Mansfield? Is the LTE transmitter in the same direction or a different direction?

What I am thinking about is some kind of shield that would reduce the strength of the LTE signals without reducing the strength of the TV signals.
 
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