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Winegard AP-2870 pre-amplifier

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Old 10-04-2012, 08:50 PM   #1
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Default Winegard AP-2870 pre-amplifier

A few months back I came across this forum and have been fascinated by all the posts -good stuff. I grew up in San Diego where we received local & LA off-the-air TV in the 50's & 60's.

If I understand “Tigerbangs NEW Prescription for Deep-Fringe Reception” he recommends a “dual input preamplifier, such as a Channel Master Titan 7777, or an AntennaCraft 10G221, or a Winegard AP-2880”. He goes on to say “In areas with a combination of both strong and weak TV signals,the AntennaCraft 10G221 is the preferred preamplifier due to it's higher input overload threshold”.

I am unable to find maximum total input specifications for the 10G221. Since the 7777 is no longer a dual input preamplifier and the 2880 is no longer made has anybody looked at the Winegard AP-2870? I hope I'm not duplicating previous posts but I haven't found any posts discussing Winegard's AP-2870. They publish a maximum total input of 10,000 μV VHF & 93,000 μV for UHF.

This information is critical to me because I have channel 26 (real), a 475 kW PBS station on a hill top 3.5 miles from my house in line with all the LA stations (52 miles away).

I am currently using a very rusty 40+ year old Channel Master CM-4228 8-bay bow tie with a Winegard HDP269 without overload. I receive LA channels 7.1 (intermittently), 9.1, 11.1 & 13.1 and most UHF channels. As soon as I get the last section installed on my tower I'll switch to the recommended AntennaCraft Y-10-7-13 VHF high-band yagi & Antennas Direct 91XG for UHF.

Thanks in advance for any information/thoughts.
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Old 10-04-2012, 10:15 PM   #2
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Holl_ands, a respected communications engineer, has published a data sheet of maximum inputs for several pre-amps, including the Winegard AP 2870. You can see his table here: http://photos.imageevent.com/holl_an...20RevA.doc.pdf

He provides a very brief discussion on how to calculate max inputs using NM's from tvfool. You'll need your report from www.tvfool.com. If you post the report here, we can help you determine overload potential. You'll need to make four test posts to the forum before you can post a link to a tvfool report. A UHF tower 3.5 miles away probably is too strong and would overload the amp, but let's see the report...
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Old 10-05-2012, 07:59 PM   #3
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Post #1
Thank you very much for the link to the Holl_ands data sheet of maximum inputs for pre-amps.
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Old 10-05-2012, 08:02 PM   #4
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The -38.4 on VHF for the Winegard AP-2870 shouldn't be a problem since the VHF stations are all either ~58 miles away (LA) or ~76-100 miles away (San Diego). The -22.3
dBm on UHF compares favorably to the -20 dBm on the Winegard HDP-269 that I've had up with my 8-Bay Bow Tie.
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Old 10-05-2012, 08:22 PM   #5
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Post #3
Took down the 8-Bay Bow Tie & removed the rotor. I got the top section of my tower installed today. Wife calling for dinner -I'll be back later.
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Old 10-05-2012, 08:43 PM   #6
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Post #4
Installed a new ECG U-106 rotor, TB-105 thrust bearing & 8' mast. Built up a new AntennaCraft Y-10-7-13 & Antennas Direct 91XG and got them mounted along with a 10 element FM band yagi. Arry turns from my family room -yea! Plan to use the Winegard AP-2870 with the Y-10-7-13 & 91XG. The HDP-269 will service the FM antenna. This will put the 91XG @ a little over 40' AGL. (The CM-4228 was @ 32' AGL.) Unfortunately, when I went to lift the tilt over tower I couldn't get it up. I'm told a lot of guys pushing 70 have that problem. Will have to build a winch system before I can report any results.
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Old 10-05-2012, 08:58 PM   #7
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IDRick, Here is the link you asked for: <http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d1349454f1d6f9 6>

FYI, if I overload the AP-2870 I have a Channel Plus NF-471 notch filter that blocks UHF channels 24 – 29 giving ~55 dB attenuation to channel 26. It will just screw onto the UHF antenna.

Thanks again for the information -very helpful.

Pete
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Old 10-06-2012, 10:40 AM   #8
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Default Winegard AP-2870 pre-amplifier

I hope this shows a screen shot of my TV Fool report.
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File Type: png Screenshot from 2012-10-06 07:24:04.png (106.0 KB, 21 views)
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Old 10-06-2012, 11:16 AM   #9
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Hi Pete,

Here is the link to your tvfool report: http://www.tvfool.com/?option=com_wr...1349454f1d6f96 Unfortunately, there are times when a space is added before the last character in the link, making it invalid. I removed the space and it now works fine!

Wow, KVCR is strong, (NM 75.2 Power -15.6 dBm) My apologies, I mistated last night. Holl_ands uses the power rating for strongest stations. So for KVCR, the peak power rating is -15.6 +7 = -8.6 dBM. According to Holl_ands calculations, the max input for two strong UHF stations is -22.5. KVCR is too strong and likely to overload the pre-amp. Your notch filter is likely to do the trick for you...

You are clearly an advanced user and I've PM'ed you how to contact Holl_ands, a most helpful man!
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Old 10-06-2012, 12:42 PM   #10
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Default Winegard AP-2870 pre-amplifier

ID Rick,

Thanks again for all the information. I attached a picture of the CM4228 before I took the test tower sections down and one showing the new array. Surprisingly, I occasionally received channel 8-1 & 10-1 from San Diego with the 4228.
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File Type: jpg Channel Master CM-4228.jpg (21.6 KB, 41 views)
File Type: jpg Array #2.jpg (98.7 KB, 40 views)
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Old 10-06-2012, 09:44 PM   #11
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Make sure the FM trap is engaged on the 2870. You've got some relatively strong FM which will compromise the dynamic range of the pre amp. A distribution amp may be a better choice if the cable run is less than 100 feet to where the cable enters the house. The Channel Master distribution amps are nearly impossible to overload & are an excellent choice in mixed strong/weak signal environments.

Also if in your shoes, I would not amplify the dedicated FM antenna. The line loss on FM is so low, it just isn't worth the risk of preamp front end overload & the added noise with weaker analog stereo stations. The HPD-269 is more prone to overload from VHF than UHF from my experience.
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Old 10-07-2012, 10:15 AM   #12
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Hoopitup2000,

Thanks for the reply. I live in a 2-story house and my cables run ~125' from the top of the tower to the garage where I power the pre-amps. From there, I have feeds that run through the walls to 4 bedrooms, the family room and living room. I use distribution amps in the garage to overcome cable loss through the house. One reason for choosing the AP 2870 was the included FM trap. My plan was to leave it in and trim the tunable trap to further attenuate KOLA @99.9 MHz (-13.4 dBm). Surprisingly, KOLA and/or KVCR (-15.6 dBm) didn't appear to cause any problems with the CM-4228 8-Bay/HDP-269 combination even when pointed right at those towers. It would be easier to take the cutting torch to those towers but with my luck they'd rebuild them.
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Old 10-07-2012, 11:05 AM   #13
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The notch filter will likely be the best solution for your sitaution if you run into an overload problem. After a little digging it looks like the filter only has a 1 db insertion loss figure which isn't bad at all.

The 2870 pre amp should help reduce any inter modulation interference as well since the UHF & VHF bands are amplified separately.

Last edited by hoopitup2000; 10-07-2012 at 11:15 AM.
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Old 10-07-2012, 02:58 PM   #14
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IDRick & Hoopitup2000,

Thanks for the interest you've shown. You've both made some very logical suggestions.

My immediate problem is to get a winch system fabricated so I can raise and lower the tower. With the last tower section installed, 3 antennas, rotor, thrust bearing & an 8' mast it is way to heavy for me to lift.

Since I wasn't sure what I was getting myself into, when I ordered the antennas, in addition to the NF-471 Notch Filter, I also ordered a couple of Eagle UHF/VHF Band Separator Combiners (Part # 25-UVSJ) and power injectors.

I think I need a mast mounted pre-amplifier to overcome ~125' of RG-6 loss to the garage (especially on UHF). I have 4 candidate amplifiers available for use:

A 40+ year old AC powered Channel Master pre-amp that has separate 300 ohm VHF & UHF inputs and a single 75 ohm output. I have used the VHF input on this amp with the FM Yagi for the last 15-20 years without any obvious overload.

The planned separate 75 ohm input VHF/UHF Winegard AP-2870.

The (test) single input Winegard HDP-269 with a UVSJ.

As a last resort, I have a single input PCT-MA-B1010-1P that I can use with a UVSJ. It is a 10 dB cable drop amplifier with a 2.7 dB (avg) noise figure that doesn't overload on strong cable signals and can support a maximum forward output level of up to +20 dBmV. It is weather proof but not designed for mast mounting, so it will be the hardest to install. As a final solution, I'm not sure how it will respond to extremely weak off-the-air signals but when I was waiting for the HDP-269 to arrive I used it with an extension cord to the roof (at the time I didn't have a power injector for it) and it seemed to work pretty well. Truthfully, I couldn't tell much difference between it and HDP-269.

From the garage I have three coax runs going to every room. One has traditionally been for cable TV in, one was configured to send the cable box/VCR/DVD outputs from the family room to the rest of the house and the third distributed FM. I've reconfigured to cable in, FM in and OTA in to all rooms.

Again, thanks for all the feedback.
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Old 10-09-2012, 11:07 AM   #15
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Aligning the AP-2870 tunable FM trap to attenuate KOLA @99.9 MHz (-13.4 dBm) proved to be quite a challenge. The amplifier enclosure doesn't provide any shielding beyond the circuit board ground plane. When powered on in my office, it pegged the signal strength meter on my FM receiver with the switchable trap in or out.

I ended up with the switchable trap set to “In” and terminating both inputs with shielded 75 ohm 'F' terminators. I connected the power injector to the amp with a shilded 'F' male to 'F' male adapter and used a 3' section of quad shield cable to the power brick. Another 3' section of quad shield RG-6 connected the power injector to the FM receiver. I built a shielded box out of double sided circuit board to enclose the 2870/power injector assembly and used a fiberglass tuning wand to adjust the trimmer capacitor. Even with all that, I had to tune the receiver above and below 99.9 MHz to adjust the trimmer for a discernible dip. Fortunately, the dip appears to be fairly broad so I used “Kentucky-windage” to center the dip on 99.9 MHz.
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