Channel 13 lowpass filters - AVS Forum
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post #1 of 13 Old 10-11-2013, 03:28 PM - Thread Starter
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I need about fifty of them. I know that a lot of people who used to use them no longer do. Does anyone here have a stash, or can point me to one?
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post #2 of 13 Old 10-11-2013, 06:36 PM
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A UVSJ is a CH13 lowpass filter; can you be a little more specific on the specs needed?

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post #3 of 13 Old 10-11-2013, 08:01 PM - Thread Starter
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Quote:
Originally Posted by rabbit73 View Post

A UVSJ is a CH13 lowpass filter; can you be a little more specific on the specs needed?

A UVSJ rolls off around cable channel 30 and doesn't have the depth of a cylindrical tier trap like the cable company relied upon for decades. I need a hard roll-off at channel 13, so that non subscribers are deprived of those channels.

A decade or so, Pico/Macom stopped listing its tier trap filters in their catalog, but had a gigantic inventory left from when cable companies depended on them and I bought twenty channel 67 lowpass filters so that I could independently "process" my local UHF channel 14 for just $6 each, and at the time, they told me of the quantities of lowpass and highpass filters they had that matched my local off-air needs, but when I went to buy in quantity a year later, they claimed they had sold their entire inventory to Allen Bradley, but Allen Bradley never has admitted to ever having had them, and believe me, I have tried and tried and tried over the years to get insiders at each company to find out what in hell happened to them but always come up empty.

There was some company in Taiwan that would make me filters for $2 each or less if I bought 500 at a time, but I have lost touch with them. "soo" something.
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post #4 of 13 Old 10-11-2013, 09:20 PM - Thread Starter
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I found the Taiwanese company and am awaiting their response http://www.soontai.com

Microwave Filter Company is now closed on Fridays, and I have contacted Eagle Comtronics.

But it looks like Gamco is out of the filter business, and their old web address produced this:

NOTICE: This domain name expired on 09/14/2013 and is pending renewal or deletion.
Welcome to: gamcofilters.com This Web page is parked for FREE, courtesy of GoDaddy.com.

C&E Filters has been out of business for a couple of years now.
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post #5 of 13 Old 10-11-2013, 09:57 PM
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Quote:
Originally Posted by AntAltMike View Post

I need about fifty of them. I know that a lot of people who used to use them no longer do. Does anyone here have a stash, or can point me to one?

Tinlee offers lowpass filters that might fill the bill.
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post #6 of 13 Old 10-11-2013, 09:58 PM - Thread Starter
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Originally Posted by retiredengineer View Post

Tinlee offers lowpass filters that might fill the bill.

I may check their site, but this isn't the grade of product that they specialize in. Last time I had Tinlee make up a filter for me, it cost about a hundred bucks, and while I can pay that for a headend filter, tier trap filters in quantity usually sell for less than ten dollars each.
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post #7 of 13 Old 10-12-2013, 07:51 AM
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If you need to make an extremely shapt cut-off, maybe it would be better to trap at the tap point with one filter, then split that one...
What's the ratio between "premiums" and "basics", so to speak?

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post #8 of 13 Old 10-12-2013, 09:41 AM - Thread Starter
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I don't need anything special. There were surely tens of millions of channel 13 lowpass filters manufactured. I'm just hoping that someone reading one of the posts I've made works for a cable company that has a crate of them they haven't thrown out.
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post #9 of 13 Old 10-12-2013, 05:48 PM
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You have probably already seen these already - "5KLP Low Cost Tiering Lowpass Filters" at http://www.microwavefilter.com/lowhightraps.htm

5KLP-216 is the Ch 13 model - there are quite a few Google hits for sites where a quote can be requested, but no pricing.
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post #10 of 13 Old 10-12-2013, 06:24 PM - Thread Starter
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Originally Posted by Channel99 View Post

You have probably already seen these already - "5KLP Low Cost Tiering Lowpass Filters" at http://www.microwavefilter.com/lowhightraps.htm

5KLP-216 is the Ch 13 model - there are quite a few Google hits for sites where a quote can be requested, but no pricing.

That's the product I was looking for, and while I am waiting for a price from Microwave Filter, I won't be buying them as someone has privately directed me to a large stash that a system operator is selling off cheap. I expect the quoted price to be between $10 and $20, but I paid a lot less than that.
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post #11 of 13 Old 10-13-2013, 07:02 AM
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I am guessing you are trying to separate WJZ RF13 from Baltimore?
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post #12 of 13 Old 10-13-2013, 07:35 AM - Thread Starter
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Originally Posted by tylerSC View Post

I am guessing you are trying to separate WJZ RF13 from Baltimore?

Nope. A senior living community in another market presently uses what are called "lifeline filters" to enable its non subscribers to watch just channels 2-13 for free, but their house channel is on cable channel 98, which believe it or not, is actually somewhere between the frequencies of channels 6 and 7. . When they were on franchised cable, regulation was accomplished by the cable company, which simply scrambled all of the subscription channels. Now they have stuffed twelve broadcast channels into 2-13, but those filters are long cylinders that combine a channel 13 lowpass filter with a midband reject filter that is incorporated into that filtering cylinder to eliminate cable channels 14-22 which are just below channel 7 at 120-174 MHz. Unfortunately, that filter apparently also eliminates cable channels 98 and 99, sometimes called A-1 and A-2, at 108 to 120 MHz.

In order to pass that house channel, they need to have a filter that inexpensively passes it at some frequency, and since they are trapping out the paid tier channels to about 30 non-subscribers, they need an inventory of about 50 of these filters, so I can't pay Tinlee or anyone a hundred dollars each. I yet ever visited this property but the maintenance engineer and I have done business for nearly twenty years as he has managed many other properties.

Thanks to a tip that was sent to me as a private message, I just bought enough such filters for my purposes at a close-out price, so I'm not looking for that item anymore. and I have ordered samples of two inexpensive midband reject filters to confirm that they will pass channel 98 (and do minimal damage to channel 7, as some midband reject filters are more damaging to channel 7 than are others).

But now, I do get to address another matter for this customer. Their headend was designed by a national company that did not perform a spectrum analysis for interference, and since this property is located just five miles from a broadcast tower farm, three of their co-called "clear" VHF channels must be looking like sandpaper wiped their screen on any TV where the shielding is not perfect, and since every market I have ever serviced has some bad midband channels, this customer might be best served by simply enabling the passing all twenty three channels that are below 216 MHz (2-13, 14-22 and 98), moving the three programs that are on noisy VHF channels into the midband, giving a few more "free" channels to non subscribers, like CSpan, CSpan2, maybe a free religious channel and a second house channel), and moving maybe ten channels up to vacant channel numbers above the highest channel they are using now, as there over a dozen presently unused, high numbered cable channels that have no broadcast interference in that market.
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post #13 of 13 Old 10-13-2013, 09:10 AM - Thread Starter
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Several years ago, I had someone make me up high-pass/lowpass pairs so I could take Washington DC 7 and 9 off one antenna and mix it with 11 and 13 from Baltimore. I think I paid $35 a pair for ten pair of each, and for that price, they actually tuned them as pairs to optimize their perfornamce, since the paired filters do interact with each other somewhat.

Unfortunately for me, the channel 9 is so much stronger coming off some of my Baltimore antennas than is the Baltimore 11 that the tuned BPF's rejection wasn't great enough by itself, so I enhanced it by putting the blocking path of a channel 9 Jointenna ahead of the 11/13 pairs to pre-weaken the channel 9 by about another 20dB. The Jointenna had to be first instead of last because it has an unshielded case and would have leaked a bunch of undesired channel 7 into the Baltimore 11/13 lead if it ws placed after that tyned pair.
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