2023 TV Antennas & Equipment

[WHJ]

With an unused coax to a tower, I thought that I might add a side mounted folded dipole pair for broadcast FM reception. I wanted to try using it along with one of my two different FM Yagi's to my RSPduo tuner for diversity reception and nulling locals for DX reception on the same frequency. While that combination might work when there is an opening, using one Yagi headed towards the local and the other towards the DX is the better combination for weak signal reception. Comparatively, the omni-directional folded dipoles add too much noise and other interference.

The folded dipoles provided an interesting reference antenna to compare reception of the wandering frequency KGCO (Crete, NE) that has been transmitting on 108.0 MHz for several months. The reception comparison is shown below:



KGCO transmits 100 watts to a 52' high antenna 24 miles away from me. KJTM operates on 107.9 running 100 watts to a 92' high antenna 21 miles away from me. Mostly due to its higher transmit antenna, KJTM is 6 dB stronger than KGCO when beaming that way. KGCO can't be received while using the folded dipoles and the other weak signals have more interference. The 7 PM KGCO ID is also attached.
KGCO 20240904.mp3
They still haven't figured out how to program the correct time zone.

[WHJ]

Reference my 10-20-23 recording on message #15, the mystery station on my 360-degree antenna rotation was finally figured out. I added it (K271CT) to the list, plus 4 others (6 - 9) heard on that frequency after the sweep:

1. KUQQ Milford, IA 196 miles at 30˚ azimuth
2. K271CT (250 watts) Creston, IA 138 miles at 85˚
3. KCKC Kansas City, MO 187 miles at 133˚
4. KZSN Hutchinson, KS 222 miles at 187˚
5. KZMC McCook, NE 200 miles at 256˚
6. KSSI (1,550 watts) China Lake, CA 1,180 miles
7. KYUN (5.2 kW) Twin Falls, ID 901 miles
8. K271CW (250 watts) Yankton, SD 133 miles
9. KQRA (4.9 kW) Brookline, MO 330 miles

The Pat Benatar song might still be from WQLF with the distorted music just after that being from K271CT.

[WHJ]

I recently completed mounting and cabling my TV reception antennas for the 2024 season. Given the number of components, I also just completed documenting that wiring. To better compare my different UHF receive antennas I made a reception strength comparison of KMCI in Kansas City (190 miles away from me). To better understand the signal comparison the receive path from the antennas is shown below.

Note two labeled Auto-Switches. Those are set to normally alternate between two different UHF antennas feeding their separate HD HomeRun tuners as shown above. For the KMCI receive comparison, those auto-switches were set to always feed the better antenna for KC reception to the tuners. The UHF antennas feeding the tuners during the receive comparison are highlighted in green. The VHF low and high antennas are also shown above.

Last year I had a bunch of single channel selectable band pass filters available to switch into the receive path. The UHF filters were mostly Microwave Filter Company 3278(4) filters. 3278.pdf (microwavefilter.com) I decided to this year try Televes 531981 AGC Combiners instead. They have up to 32 single channel filters. Due to not wanting to use them on the low VHF channels due to their low dynamic range there, that provided me with a filter available for each channel being used. The 531981’s have superb dynamic range on the UHF channels, adequate dynamic range for the high VHF channels, but inadequate range for the low VHF channels. HL-SJ frequency combiners are a better option. Pico Macom TruSpec ATX HL-SJ, VHF high-low separator / combiner – Ness Electronics, Inc
Due to the reduced input sensitivity of the 531981, it needs a preamplifier before it for weak signal reception. And its output level needs to be reduced unless you have significant loss in filters and/or muti-splitters or the HD HomeRun tuner will be overloaded.

The updated KMCI receive comparison is shown below.

[WHJ]

Thanks for the WQLF suggestion--that seems likely. It was the one station that I could not positively identify. It was there and then gone--probably via meteor scatter.

As expected, the others recorded are almost always received with my new antenna.

I felt good about just receiving KPUL 101.7 6kW ERP in Winterset, IA. That brought back memories of my running their full marathon race as part of their Covered Bridge Festival. Not having hosted that since 1983, they have downgraded the distance to just a 5k. Winterset's other claim to fame is being the birthplace of John Wayne and having his birthplace museum.

[Jim Thomas]

Amazing stuff Bill. My guess is your unID between KUQQ and KCKC in the recording is WQLF Lena, Illinois (NW corner of state), which plays classic rock (the Pat Benatar song). Imaging is Q 102.

I wish I had your type of setup for antennas but I live right across from a national airport and it probably wouldn't be allowed.

[WHJ]

I decided to add a new antenna to go along with my TV channel 6/lower FM antenna to cover the upper two thirds of the FM broadcast frequencies. I started with my 10-element channel 6 design and added 4 elements on a longer boom to create a 14-element antenna centered on the upper FM frequencies. I got it up on my own earlier this week.


It is 81 feet high, below a Winegard HD7698P antenna. The new antenna was designed to have minimal beamwidth with maximum rejection of a wide range of azimuths. That performance can be heard on the recording which I made of reception on 102.1 MHz when I made a 360˚ rotation of the antenna.

FM14 360 Degrees Rotation 102x1.mp3
The stations on the recording are in order:

1. KUQQ Milford, IA 196 miles at 30˚ azimuth
2. ? Unknown station(s) One since IDed as K271CT Creston, IA 138 miles at 85˚
3. KCKC Kansas City, MO 187 miles at 133˚
4. KZSN Hutchinson, KS 222 miles at 187˚
5. KZMC McCook, NE 200 miles at 256˚

There was minimal tropo-helper during the time of the mid-afternoon recording. The antenna design is a good example of the fact that antenna gain is not due primarily to the number of elements but rather the boom length is more important. Its azimuth pattern at its actual height is shown below.


Its free space gain is 14.44 dBi as compared to the 13.43 dBi gain of the InnovAntennas 20-element 88-DES-20 antenna. Of course, InnovAntennas had to broadband their antenna more. With the local stations serving as beacons, I have been able to confirm that my antenna’s performance closely matches its design.

[WHJ]

While there hasn't been much tropo lately, the Televes Smartkom 531981 has helped receive distance stations. And its single channel filters for each channel have helped receive weak stations on channels adjacent to strong locals. An example of that is shown in the reception of the weak signal reception of K23AA and its 8.8 kW signals to a 140M high antenna 52 miles away vs. the channel 24 signal from KSNB's 260 kW, 430M high antenna 14 miles away. Sometimes K23AA can only be received when the Smartkom is used.

The difference between the two is shown below.



KSNB 24 is using KOLN's tower which hides KSNB's listings above. You just have to ignore the HDHR's signal ratings. Instead, you need to use its signal/noise ratio to show changes in receive strength.

I'm showing a VHF signal (WIBW CH13 in Topeka, KS 145 miles away) since different receive antennas are cycled on UHF for this tuner.

[WHJ]

As a TV DXer I was unsure how to connect the Smartkom to multiple antennas. Locking to a channel to just one antenna (of multiple) didn't make sense. I currently use a passive frequency selective combiner (Televes 404010) to feed separate low VHF, high VHF and UHF antennas to the correct channels to my "Garland, NE 4K 4-Cycled Antennas" HDHR Flex 4K. I decided to instead use my Smartkom as a combiner.

Since the Smartkom does not quite have enough filters/AGCs for all channels, I am using a True Spec HLSJ low VHF plus high VHF and above combiner to add my Channel 2 & 3 Yagi to just the low VHF channels. I was concerned about the Smartkom's reduced dynamic range on low VHF anyway. Most receptions will now be "green" on that HDHR due to the Smartkom's AGC. That HDHR confuses things by cycling through connecting 4 different UHF antennas, with two antennas having priority and connected more often. The two primary antennas include a rotatable 64-element UHF antenna at 92' and a 22-element UHF log periodic at 61' fixed on Kansas City. The other two UHF antennas cycled include a Fracarro Sigma6HD antenna at 76' fixed to the west and a Stellar 30-2440 antenna fixed to the east. The only high VHF antenna connected is a 12-element Stellar 30-2476 at 81' fixed at 160 degrees azimuth.

[WHJ]

TELEVES SMARTKOM 531981 TV AGC AMPLIFIER

I have been trying to evaluate all the TV RF preamplifiers and use the best of those. Until now I have avoided the Televes Smartkom 531981 preamp due to it appearing to be made more for cable TV companies rather than weak-signal home viewers. That is best shown by it having a noise figure of 6.0. But, after experimenting with a circuit around an Analog Devices AD8368 AGC IC I thought that it was time to try Televes better Smartkom AGC amplifier. It can have up to 32 different single channel filters activated with a separate AGC for each channel. This is enough for almost all 35 of the currently available on-air channels. All but the very weak signals will have the same level at the Smartkom’s output.

Jumping quickly to the results, this morning’s tropo opening to Kansas City seemed like a good time to see its use in action. To leave enough space for labeling my spectrum analyzer’s display, below are the stations being received on the upper 100 MHz of the UHF TV channels while beaming towards KC.
Most of the above stations are from Lincoln (14 – 25 miles from me), Omaha (57 miles), and Kansas City (190 miles). Omaha’s ATSC 3.0 KXVO had significant interference from KMBC in KC. That is KMBC’s ATSC 1.0 pilot on channel 29.

I was expecting the AGC level would be frozen after the automatic programming had been activated. However, the AGC appears to always be active responding to changes in the received signal level. The above reception was this morning after 7 AM compared to the automatic programming last night. That was quickly followed by activating all UHF and high VHF channels whether they were receiving signals or not. There were not any KC stations being received then. That programming is shown below.

The default output level of the Smartkom is 85 dBuV (which I measured as 81 dBuV). That provides my HDHR Flex 1K with a 100% signal. So, almost all the signals will be at a green level. The quality might be lower, like it was for KXVO above. With all signals being at about the same level, strong signal interference won’t be as bad for adjacent channels, but that high level still worried me. Setting the Smartkom output level to 70 dBuV reduced the HDHR level to 92% (still green). I decided to go with an output of 65 dBuV for now. There is obviously a lot of reserve to cope with the loss of any passive splitters which are being used.

I ran my standard RF preamplifier evaluation tests. Not surprisingly, its weak signal sensitivity for a 15 dB MER was poor. With its 6.0 noise figure that was expected. However, its strong signal capability and dynamic range were both the best that I have measured! With my existing tower mount preamplifiers left in place to handle weak signals, it is likely to be used inside. Combining the Smartkom results with the Analog Devices AGC and three of my most used preamplifiers is below.

The dynamic range of the Smartkom goes down on the high VHF (90.8 dB) and low VHF (to a marginal 82.9 dB). Depending on the input signal level, the UHF gain ranged from -29 to +50.8 dB! There is a small regular picture of the Smartkom above. However, what’s inside? That is shown below.

I also used my spectrum analyzer’s tracking generator to provide some measurements. That provides a swept frequency output which can confuse the many single channel AGC’s. With things adjusted to minimize those negative effects, the frequency response of the preamplifier with all UHF and high VHF channels activated is shown below. Any RF outside of the broadcast frequencies is not going to cause any problems.
The frequency response of the AGC with just the 536 – 542 MHz channel 25 being shut off is shown below.

With just channel 6 activated, the response and FM attenuation is shown below.
Neither quite meet the >30 dB rejection +/- 1 MHz specification, but it is still pretty good. FM signals above 89.5 MHz should not cause any problems.

Below are a bunch of figures which show the output dBuV with a varying input level. I used my Rohde & Schwarz SFQ test DTV transmitter and EFA test receiver to make output level and MER measurements. It also shows the noise output level without any input.

Finally, a more complete chart of my preamplifier evaluations is shown below. Many different versions of the preamplifier models being used have been tested. A close look will show missing figures for the Televes Avant X Pro 532121. The discontinued European model for their 8 MHz channels works best in the USA when filtering in three adjacent channel groups. Four USA channels will fit there. With single channel filtering level jumps will occur when a USA channel is located in two European channels. That will hurt reception of the USA station.


For weak signal reception a low noise preamplifier is needed in addition to either the Smartkom or Avant smart combiners.

[WHJ]

I just completed checking the level from 12 of my TV antennas. I increased the level from some of my antennas and decreased others.

It was interesting checking the level from my channel 6 antenna. The BROADBAND level after my FM filter was 80 dBuV maximum while before the filter it was 104 dBuV. My HDHR tuners are fine with 80 dBuV but would overload with 104 dBuV.

[WHJ]

Recent good openings have made me wonder if all of the strong signals added up causing collective overload of my equipment. I considered adding a RF AGC to prevent that. I have one Televes preamplifier with built in AGC. It can prevent overload of other equipment which has a limited dynamic range, but the preamplifier's dynamic range is just typical of other preamps.

I did not find too many other options. I considered the Analog Devices AD8367 and AD8368 IC's. See: AD8368 (Rev. C) (analog.com) The AD8367 is just rated to 500 MHz and the AD8368 has a worse noise figure (10.0), I thought that I would experiment with both. They are meant to have a now noise amplifier before the AGC's as in done in the Televes preamplifiers.

I purchased some of the low-cost evaluation boards on eBay and tested them using my preamplifier standards:

I did not like the AD8367's limited frequency response and 200-ohm input impedance. The AD8368's noise figure concerned me, but I liked it having its AGC voltage available which can be converted to a measurement of its collective input level.

I added 75 to 50-ohm input matching and a 50 MHz high pass filter to the AD8368 and added a voltage measurement display.

I connected one of my Winegard HD7698P antennas to the unit and first measured 0.378 volts. That translates to 85 dBuV. I measured the overload level of HDHR5 and Flex 4K tuners as being 92 dBuV. That's a small safety margin. I later measured the same antenna with the AD8368 measuring 0.533 volts/92 dBuV--precisely at the limit. I then pointed the antenna directly at my local DTV stations. That read 0.749 volts/99 dBuv. That is what I expected--over the limit at worst case antenna heading!

My upgrades to some of my Flex 4K's has improved the situation. That increased its overload level to 104 dBuV. I need to make additional tests to more antennas.

[WHJ]

The vertical dipole appears to have more advantages than I first thought. I was worried that they never would be better than my horizontal Yagi's due to their added gain and directivity. At least when an opening is just to one signal, the vertical dipole was occasionally better. Also, having an omnidirectional antenna is useful to point to a new opening. That occurred a couple of times over the weekend when there was an opening to Las Vegas when my directional antenna was pointed to the southeast states.

The Yagi's have long been useful during openings in multiple directions. That permits reception of both southeast states or New England depending on my antennas heading.

Due to the advantages of having the vertical dipole I have added it to my third HDHR tuner. My equipment connection diagram in my first message has been altered to reflect that change. My HMC421 antenna switch control will be set most of the time to alternate between feeding my channel 6 Yagi or my vertical dipole to my third HDHR tuner. Depending on conditions, I can switch to feed only one of the two during an opening. When my fourth tuner has been connected to TV BandScan, I can have all four permanently connected to a tuner.

[WHJ]

The elevation lobe compression depends on the number of antenna bays (effectively dipoles) which are vertically stacked. It's best if those are one wavelength apart. That distance is the inverse of the frequency ratio. You show the elevation pattern of a 24-bay channel 49 (683 MHz) antenna. A 24-bay 97.5 MHz FM antenna would need to be seven times the size of your UHF example. That's not practical. FM antennas generally have a 12 or 14 bay maximum. Some elevation patterns of FM antennas are below:

Due to power licensing, a 4-bay antenna will require much greater transmitter output power than a 12-bay antenna for 100 kW ERP. Both will produce the same signal at the coverage extreme. The power bill will be much lower when the 12-bay antenna is used. However, everybody inside the coverage extreme will have a stronger signal with the 4-bay antenna.

Yes, filtering the stronger signals from FM and DTV signals can aid reception--that's part of the reason that I am using so many filters. Go to the following web page to see my recent 24-hour low VHF receptions: https://forums.wtfda.org/forum/wtfda...ot-frequencies

[Crazy Monkey]

I do not have excessive FM overload, but enough to limit things. I have two 100 kW FM stations about 14 miles away and a low power FM 8 miles away. 1.5 to 2 miles away your local FM signals should be beaming over your head (depending on the transmit antenna height and gain). It is the combined strength of all the signals going to your tuner and its filters which matters.

For comparison, I made field strength measurements on a channel 23 DTV station which use an antenna about 450' high. I made measurements along one azimuth radial. Starting close to the tower, its signal strength went up as went further from the tower. Only after I reached ten miles from the tower did the strength start going down with increased distance.

Ok, thanks.

I've come across some graphs in the past which showed just how much power was reaching the ground at a certain angle beneath the tower, but I haven't been able to find these graphs for FM. From my understanding (and I was told), FM signals don't have this tight pattern like DTVs do. But maybe someone can provide actual graphs for this. It seems from my experience, the FMs here are far worse overload. But I do notice that filtering out the strong 1 to 2 mile DTV transmitters raises the signal quality of some of the weaker DTVs by 10 to 20%.

Here is an old example of what I'm referring to...

[WHJ]

I do not have excessive FM overload, but enough to limit things. I have two 100 kW FM stations about 14 miles away and a low power FM 8 miles away. 1.5 to 2 miles away your local FM signals should be beaming over your head (depending on the transmit antenna height and gain). It is the combined strength of all the signals going to your tuner and its filters which matters.

For comparison, I made field strength measurements on a channel 23 DTV station which use an antenna about 450' high. I made measurements along one azimuth radial. Starting close to the tower, its signal strength went up as went further from the tower. Only after I reached ten miles from the tower did the strength start going down with increased distance.

The chart shows the low band filters that I use. I fortunately have four different low band antennas. My channel 2 & 3 antenna uses a Mini-Circuits SCLF-65 filter:

As the graph shows, even 88.1 FM is down by 30 dB.

My channel 4 & 5 antenna uses a Mini-Circuits BPF-A69 filter:

By the time that you get to my first close 100 kW station's frequency (96.9 MHz), it's down 25 dB.

My channel 6 antenna uses a CirQTel FBT filter:

It's down a bit further on that first station.