Some Antenna Photos and Tests

[tripelo]

Tests were conducted in 2011 to evaluate performance of some TV antennas.

The tests involved a signal source feeding a CM-4228 at ~45 ft AGL radiating to antenna under test located ~150 feet distant at ~level height to source antenna.

The signal source was a homebrew signal synthesizer, remotely controlled at the receiving location by a notebook PC.

Received signals from the test antenna were measured using a homebrew wideband power meter with digital readout and logged into an Excel spreadsheet.

The test frequencies were chosen to represent channels that might be of personal interest.

This location is rural, the only UHF strong signal is at Channel 14; the frequency band was omitted from the tests.

The last image below shows results from comparing four antennas:

- Channel Master 4228 (the most common of the older versions)
- Channel Master 4251
- Antennacraft P7
- Antennacraft SuperG 1483 (the stacked Hooverman version)







The decibel scale is relative for a comparison between the units.

Caveats:

Each antenna was installed at the test mast for a few days while several preamps were individually tested with that particular antenna. So, each antenna was measured days apart from others.

There may be some SWR effects in the antenna gain patterns, affecting each antenna differently.

Comments:

In general, testing against distant weak TV signals was consistent with the measured results. CM-4251 was best on upper UHF. P7 performed well on mid UHF channels. SuperG 1483 was comparably good on mid-20 range channels.

Attachment 496

[GroundUrMast]

Are the signal source and/or power meter proprietary works? Or can you share details of those with us also?

Thanks for the work, and willingness to share it with us.


Oh, nice towers.

[tripelo]

Thank you GroundUrMast, for your kind words.

Originally Posted by GroundUrMast

Are the signal source and/or power meter proprietary works? Or can you share details of those with us also?

No, not proprietary. Yes, can provide some details.

The synthesizer is based on IC Silicon Devices SI570. PDF available here:

http://www.silabs.com/support%20docu...docs/si570.pdf

The version (BBB) that covers range from about 10 MHz up to about 950 MHz was used.

Some kits containing major parts of the circuitry and components are available from SDR hobbyist groups. SDR=Software Defined Radio

http://en.wikipedia.org/wiki/Software-defined_radio

SDR-Kits were used in this particular synthesizer.

http://sdr-kits.net/QRP2000_Description.html

The components are not complicated to assemble, nearly all were thru-hole. The synthesizer IC is SMD (surface mount).

One should have output attenuators, power supply, metal housing, and filters. Other modifications and items are useful, but with these become quite useful. USB power can be used when near such, otherwise wall wart with additional filtering can be used.

The controller for the synthesizer chip is USB based.

Software to control the synthesizer from PC can be obtained on the web.

For remote control one can use USB to LAN adapters at each end of the circuit, then use whatever LAN devices one desires in between.

In this case, for remote control, ~165 feet of Ethernet LAN CAT5e cable was used, probably beyond specifications without repeaters, but worked fine. To reach greater distances, one could probably use wireless game bridges, or something similar.

The wideband power meter is based on Linear Technology LT5534 integrated circuit.

http://www.linear.com/product/LT5534

Haven't seen a kit of parts for such.

Manufacturer provides a good reference design. Found a PCB made for another similar part and adapted it. It is all SMD.

For accurate results, one should provide for a matching circuit on the input. Resistive pad matching at input combined with ~ 10-20DB fixed attenuation provides a reasonably low SWR. Can use ordinary DMM for digital readout.

Need: power supply, metal housing, and external attenuators.

Below is an image taken in 2011 around the time of the preceding test. The workbench is behind that window, inside the building next to the receiving antenna mast.



Shown on part of the workbench, among cables, planks, and bricks; from top to bottom, left to right:

- Some version of Research Communication preamp (loose)
- Blonder Tongue FSM-11 signal strength meter with brick
- Antennacraft preamp power supply (loose)
- Signal synthesizer (in aluminum case)
- Half Wave Loop balun
- DMM (Red)
- HP notebook computer
- Holland Splitter
- Various fixed attenuators (in-line)
- Another Research Communications preamp (in-line)
- Power Inserter (in-line)
- Winegard Power Inserter (loose)
- Fixed attenuator (Red, in-line)
- Wideband power detector (blue aluminum case)
- Some version Winegard preamp
- Channel Master preamp (loose)

Oh, nice towers.

Thank you.

The near tower has the transmitting CM-4228. Hard to see, it is mounted directly behind the CM-4251. The tower and that particular CM4251 have stood for more than 40 years.

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[Pete Higgins]

tripelo,

I finally got cleared to post. As I mentioned last week, I’ve contacted Antenna Craft to see if they will sell me a Super G and what it will cost with shipping. Still haven’t heard back from them yet so I'll probably try to give them a call.

Again, thanks for pointing me to this most interesting information. You do have an envious test setup.

[tripelo]

Originally Posted by Pete Higgins

...

I’ve contacted Antenna Craft to see if they will sell me a Super G and what it will cost with shipping...

Very interesting.

That was a good idea to contact Antennacraft. Maybe we can learn something from it. Curious as to what Antennacraft's response will be.

-----------------------

Pete, thank you for the compliments.

[Atis]

Just chatted with a rep at www.summitsource.com she said both the sigle and stacked version are in stock there.

[Pete Higgins]

The problem isn't availability, its paying for the excessive shipping weight.

When I went to the Summit Source web site to order it, in addition to the $109.95 for the antenna, they want $76.88 for ground shipping. That brings the total to $186.83!

They list two different weights, one for the United States Postal Service @ “37 lbs, 11.62 oz”, and a second for UPS / FedEx @ “(2 x 37.72575 lbs)”.

I contacted Antennacraft to ask about the weight and they said "We pack the Super G1483's 2 per box when they leave our facility. The weight for a 2 pack is 8.5#'s. So each antenna would weigh approximately 4.3#'s each.”

I then talked to Erick @ Summit Source and he confirmed that even though the AntennaCraft shipping weight for a box of two Super G1483's was only 8.5 lbs the Summit Source computer takes into account dimensional weight and ground shipping would cost me $76.88.

I think before I shell out $186.83 to try one of the commercially available Hoverman designs it might be prudent to cost out building one of the more versatile Grey-Hoverman designs.

[tripelo]

No intention to divert from other antennas and tests, or other related.

Took down an antenna this morning and thought it (or the story) may be interesting to someone.

It's a Log-V antenna, VHF (low and high), maybe FM.

It was located at an apartment complex and appeared to be a potential hazard to those who lived there. From the ground, the antenna looked to be in good shape (see photo). Realizing that the antenna might soon be lost to wind, an inquiry was made and the responsible people were glad to have it removed.



The antenna originally had four guy wires that had long since broken. The guy wire remnants were so degraded that flexing a couple of times, they crumbled.



.

Turned out, the antenna is in good shape. Whoever designed and built it, made it to last. Element-to-boom support is very sturdy. All the elements folded back to the boom perfectly, no insulator was cracked. On the ground, the gold anodizing is still visible.

The antenna could be vintage mid-1960s. Certain features in the construction point to early times. Mid 60's is about the earliest date that Log-V antennas were available, and was probably about the time the apartment complex was constructed. Could be a Radio Shack antenna. Seems that during the 60s, Radio Shack marketed several major brands; Finco, Channel Master, JFD, and others.

If anyone has clues to it's origin, please post.

Anyhow, back to regular program.

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[Pete Higgins]

tripelo,

Great find. Wish I could find an old Channel Master 4251 that someone wanted removed.

I got started last summer playing with a 40+ year old Channel Master 4228. If it had received CBS on channel 43 (2.1) as well as it received NBC channel 36 (4.1) I probably wouldn’t have built my new system using a 91XG and an AntennaCraft Y10-7-13. Now, the 91XG always gets CBS but rarely gets NBC and the CM-4228 always gets NBC but rarely gets CBS. Go figure! I have them connected through a coax switch in the garage so I can switch between them when needed.

It would be interesting if you could compare this old LPA to some of the current crop of VHF High antennas like the Winegard YA-1713 or the AntennaCraft Y10-7-13 Yagi Antennas.

Enjoy.

[tripelo]

Originally Posted by Pete Higgins

... Wish I could find an old Channel Master 4251 that someone wanted removed.

Yes, hope you can find such. Was the CM-4251 popular in California?

I got started last summer playing with a 40+ year old Channel Master 4228. If it had received CBS on channel 43 (2.1) as well as it received NBC channel 36 (4.1) I probably wouldn’t have built my new system using a 91XG and an AntennaCraft Y10-7-13.

You have some nice antennas.

Interesting that you have found such a difference between the antennas. As you probably know, for the 91XG, its directivity (gain) increases with frequency, whereas the 4228 has relatively flat gain characteristic from around channel 20 or so, through channel 51. Unless there is some other factor, the 42 MHz difference between the two channels means quite a lot for the 91XG.

Would be interesting to see the TVfool predictions for your antenna locations, can you post them?

I have them connected through a coax switch in the garage so I can switch between them when needed.

Seem like a workable solution.

It would be interesting if you could compare this old LPA to some of the current crop of VHF High antennas like the Winegard YA-1713 or the AntennaCraft Y10-7-13 Yagi Antennas.

Yes, good thinking. That would be quite interesting.

Maybe that could be feasible. Right now, the Log Periodic is here in suburb Dallas, and the good antenna range is in KY. The LP is too long to ship by conventional means. And, probably the most interesting antennas (that I have) to compare against the LP are also located in KY.

Although, have done antenna comparisons at both locations (KY and here).

Such a test would be interesting and worth some thought and effort.

[tripelo]

The vintage antenna (previous post) is a Finco CS-V10.



The image is from: Popular Science 1967

It is covered by Finco patent No.3,427,659.

FISHBONE TYPE ARRAY WITH DIPOLE SPACING INCREASING TOWARDS THE SMALLER END

The patent describes Finco’s discovery that log periodic dipole antennas could achieve greater gain for TV frequencies if the element spacing was tapered somewhat wider towards the front. Previous thought was either; logramithic spacing which tapered smaller spacing towards the front, or uniform spacing.

In the patent, an example antenna lists dimensions and increased gain values. The dimensions given in the example match those measured on this CS-V10 antenna.

The patent was originated in 1964 and issued in 1968.

Interesting in this same time period , The University of Illinois (holder of the log periodic patent) was in litigation with several TV antenna manufacturers, of which Finco (Finney) was one.

[Pete Higgins]

tripelo,

here you go:
http://www.tvfool.com/?option=com_wr...1dda169109ca5c

FM Fool shows 99.9 MHz @ -13.4 & 91.9 @ -26.9

I've got to run to the Dentist

[tripelo]

Originally Posted by Pete Higgins

...If it had received CBS on channel 43 (2.1) as well as it received NBC channel 36 (4.1)...

Initial thought:

You cannot receive Channel 43 very well because it isn’t there (that is; in the TVfool table)!

Then, after eliminating analog channels from the table, channel 43 shows.

That’s a difficult situation to receive such a weak signal in the presence of very strong signals.

--------------------
2nd thought:

When applied to your area, TVfool signal prediction algorithms (presumably based on Longley-Rice model) must not be as accurate as they usually seem to be.

1. It’s unlikely that an ordinary TV receiver can simultaneously process signals having a dynamic range of 106.5 dB (difference between KVCR, -15.6 and KCBS, 122.1).

Then, recalling that you used a notch filter to essentially remove KVCR, obviously improving the dynamic range situation, tho still very challenging for an ordinary TV receiver.

That’s not to mention the complications of two FM stations at –13.4 and –26.9 dBm, plus some more moderately strong TV stations.

2. The available antenna gain is insufficient to compensate for a noise margin of -22 dB.

-------------------
For many, receiving KNBC, at predicted noise margin =-16.8 dB, would be a challenge.

Do you receive both KNBC channel 36 (-107.7 dBm) and KCBS Channel 43 (-112.9 dBm) on their assigned antennas throughout the day (say most of 24 hours)?

-------------------

Regardless the accuracy of TVfool predictions for your particular location, you undoubtedly have a situation that challenges the dynamic range of amplifiers and tuners.

Pete, you have an interesting situation. From reading in other forums, you have worked out a good approach toward solving the problem (filters, high dynamic range drop amplifiers, and such).

[Pete Higgins]

tripelo,

We’ve had the Time Warner’s “Everything” package for years (my wife even got me the Playboy channel) so OTA is mostly a hobby. I originally started just trying to see what I could get with a 40 year old Channel Master CM-4228 8-Bay Bow Tie. After receiving both VHF & UHF channels from LA & San Diego I decided to see how much I could improve my reception. Things just kind of grew from there.

I am not currently using the Channel Plus NF-471 notch filter.

My original plan was to use a Winegard AP-2870 pre-amp. with separate VHF & UHF inputs. I tried the Channel Plus NF-471 55 dB channel 26 (KVCR) notch filter in-line with the UHF input to the 2870 but the amp. overloaded so badly that I almost didn’t get anything. I also tried both antennas into a UVSJ, through the notch filter and into my Winegard HDP-269 with basically the same result. The PCT MA2-M’s don’t seem to overload, even without the notch filter.

A pictorial of my new antenna array setup can be found @:
http://www.digitalhome.ca/forum/show...t=42426&page=7
(Post # 3348).

The CM-4228 is on a push-up mast with a rotor and is using the HDP-269. I have the coax from the tower array and the HDP-269 going into a coax switch in the garage, the output of which feeds my PCT MA2-4P distribution amp.

Channel 2 seems quite reliable on the new array, but the array rarely gets channel 4. By the same token, the old 8-Bay always gets channel 4 but almost never can hold channel 2. A lot of the one hour shows my wife & I like are on CBS (Ch. 2.1) so when the 8-Bay couldn’t pull it in I was motivated to come up with a better solution. To that end my new setup does what I wanted. I’m just not sure what the mechanism is that prevents the new array from getting NBC (channel 4.1). For the most part, the SNR between the two antennas is within 2-3 pts. with the 91XG higher in a little over half the cases. It could be as simple as it has better response on RF 43 (2.1) than the 4228 and the 4228 has better response on RF 36 (4.1).

[tripelo]

Pete, have been out of town for a while. Was actually in KY at the main antenna test location, and climbed above the top of the tower a few times. Above the top, to be explained later.

Please, feel free to update on your antenna work.

----------------------

In the meantime, this is an image taken in 2009 of the main tower (lower part shown in Post #1) as it has stood since I personally erected/installed in the early 1970's. The tower and antennas were largely ignored all those years, (meaning almost no maintenance), although they reliably provided TV reception for my parents.

The large VHF antenna is a Channel Master Quantum CM-1110.

The plastic bucket lodged in the tower was there temporarily for convenience to hold tools and such. The photo was taken just before the CM-1100 was lowered to the ground.

Since that time in 2009, there have been several different antennas residing above the tower top, or near the top of the tower. Maybe later can show some of the other antenna arrangements.
.

[Pete Higgins]

tripelo,

Good to hear from you.

As I said in my last post, the CM-4228 was on a push-up mast with a rotor and was using the HDP-269. I ordered a Winegard YA-1713 Prostar 1000 10 El. Hi-Band VHF Antenna to go with it.

I thought I would use that combination to test the Winegard pre-amplifiers that overloaded with my tower array.

I installed the YA 1713 above the CM-4228 and ran two new 17’ pieces of RG-6 down the mast, one from the CM-4228 (white) and the other from the YA-1713 (black), so I could experiment with UVSJ's, my HDP-269 and AP-2870, and several cable drop amps I’ve collected without having to lower the mast for each change. In anticipation of testing the pre-amps, I ordered three Antennas Direct FM Band 20 dB traps and two 3 dB & two 6 dB in-line attenuators to go with my Channel Plus 55 dB channel 26 notch filter.

When I got everything hooked-up, the new Winegard YA-1713 wouldn’t receive channels 7 or 13. It is mounted about 30’ south and 6’ lower than my Antenna Craft Y10-7-13.

When it wouldn’t work with my amps., I hooked it directly to the cable that runs to my PCT-MA2-4P distribution amp. and was able to receive 8 (8.1) & 10 (10.1) out of San Diego and 9 (9.1) & 11 (11.1) from LA. I then disconnected the YA-1713 and hooked up my Channel Master CM-4228 to the cable that runs to the PCT-MA2-4P distribution amp. and got a very pixelated channel 7, a fairly solid 9, intermittent 11 and a pretty good 13. All 4 LA stations measured high “Green” on my SNR meter with the Antenna Craft Y10-7-13 switched in (of course it has a +15 dB MA2-M mounted right behind it). Adding an amplifier to the Winegard 1713, at the base of the push-up didn’t improve/add the missing LA stations. It did considerably improve VHF reception from the CM-4228.

Since I only had one 50’ run of RG-6 going from the base of the push-up mast into the garage, I had to get up on the roof to switch antennas. I added a second run (white) so I could route the UHF and VHF signals to a garage coax switch separately. After I got tired of running out to the garage to switch between antennas I added a 4th RG-6 run into my office so I could monitor both push-up antenna signals from the office. That’s kind of where I’m at right now. With no amplifiers in-line, the 4228 actually does better getting channels 7 & 13 than the YA-1713. Mid-band, the YA-1713 does better.

I sent Winegard an email on May 13th to see if they could think of any reason performance would roll off that dramatically at the top & bottom of the YA-1713’s band. So far I haven’t heard back from them. They probably got the email and thought I was nuts!

Solid Signal sent me an email flyer for an 8-Bay “Solid Signal Xtreme Signal HDB8X High Definition Blade 8 Bay Xtreme Antenna (HDB8X)” for $59.99 with $0.05 shipping. It looks to be 2 4-Bays on a swivel with 2-BALUM’s hooked to a combiner. It has the multi-directional feature like the new Antennas Direct DB8e and blade elements similar to the 91XG. For $60.04 delivered I couldn’t resist. They claim a maximum gain of 25 dB when both sides of antenna are parallel, which I believe defies the laws of physics, but if their matching harness arrangement is any good at all, I expect it will perform about as good as any other 8-Bay. They don’t expect to ship them until after 1 June.

Next, I want to pull down the push-up, inspect the YA-1713 and swap the 17’ cables. I’ll probably also try it on my tower and try the Antenna Craft Y10-7-13 on the push-up.

I can’t drop or raise the push-up mast by myself. I have to set a ladder in front of it so I can reach the U-bolt through the upper stand-off bracket. Once I get the U-Bolt off I need somebody to hold it while I move the ladder out of the way so it can be laid horizontal. Going back up, I need somebody to hold it so I can position the ladder and re-install the U-Bolt. There’s a real shortage of people in my neighborhood lining up to climb on a roof to raise & lower antennas! Since I’ll want to try the new 8-Bay anyhow, I’ll probably wait until the HDB8X gets here to do any more YA-1713 testing.

The tower got too heavy to lift, even with help, so now I can lower and raise it by myself with help from a 110 VAC winch. When I have the new patio roof put on I’ll try to figure a way to get winch’s working for the push-up and my other tower.

Take care.

[tripelo]

Pete, looked back at your tower array, mentioned in your earlier post.

Direct link to post #3348 here:

http://www.digitalhome.ca/forum/show...postcount=3348

As to why the poor reception of the YA-1713 for VHF compared to the 4228:

Not a lot of suggestions, there are several variables.

The YA-1713 and most antennas have a bit less gain at the band edges (in this case; channel 7 and 13). If there were extra attenuation in the YA-1713 path, then the normal roll-off of the gain vs frequency pattern for the YA-1713 could become more obvious.

As you mentioned, reversing the cables between the CM4228 and the YA-1713 seems a good step.

If you have cables with pre-installed factory connectors, they sometimes cause problems.

The YA-1713 has a snap on balun that could have a problem.

-----------------------

Your thoughts on the new 8-bay (Solid Signal HDB8X) will be interesting. Since it has separate reflectors (not-continuous like the 4228) then it will probably have less response for your VHF signals.

[Pete Higgins]

tripelo,

I made up both of the 17’ cables going to the antennas just to simplify testing. Since I still had both white & black rolls of coax, I arbitrarily used white for the UHF run & black for the VHF run. I installed the boot that came with the YA-1713 on the black cable & new Channel Master (PCT) compression connectors on both. I doubt that I have a bad connection on the black cable but that’s why I want to swap them.

The original black cable that runs into the garage is probably 30 years old with crimp on connectors. It is the one I originally used to compare both antennas so I’m pretty sure it is still Ok. The “new” cable I pulled is a 50’ “factory” Magnavox M61210 roll of white RG-6 with molded ends that my son gave me. I have swapped the antenna feeds between both of the garage runs and can’t tell any difference so I’m pretty sure both of those are Ok.

The 4 cables from the garage to my office are new RG-6 runs with compression connectors that are routed between the downstairs ceiling and the upstairs flooring through PVC conduit, then down through the office wall to a metal plate with 4 F-81 barrels.

The YA-1713 balum looked like it could install either of two ways so I checked online with Winegard and found that it didn’t make any difference. I didn’t pay a lot of attention to it but as near as I remember it just looked like a clip-on microstrip line matching transformer. It should have been foolproof. If I can get it apart without destroying the plastic housing I’ll inspect it for any signs of damage or missing parts.

I think the most informative test will be dropping the tower and swapping the VHF antenna locations. That will put the YA-1713 in a known good signal location with plenty of amplifier gain and all new end-to-end proven cables.

Of course I want to compare the HDB8X to my 40 year old Channel Master CM-4228. That may not sound fair, but last summer I compared the 4228 to a brand new 91XG and in the same location both antennas provided about the same SNR +/- ~1 dB on most channels. I also want to see how it does on channel 36 (4.1 NBC) & channel 43 (2.1 CBS) since the 91XG has trouble with NBC & the 4228 has trouble with CBS (from the same location).

My San Diego UHF stations arrive from ~169 deg. and seem pretty strong. One of the things I also want to try with the HDB8X is pointing one panel towards San Diego and the other towards LA (292 deg.) and see how the 4-Bays do through the combiner and/or individually. That’s assuming that they will swivel through 123 deg. Fortunately, I have the rotors so if I don’t get the angle set to exactly 123 deg. I can “bump” align each panel for best signal.

I’ll be waiting to hear how you climbed “above the top of the tower”.

[tripelo]

Pete, you have an extensive cabling arrangement.

Your idea of swapping antenna positions is a good one. Vertical signal layering can cause a substantial signal strength variation over relatively short distance when antennas are relatively close to ground (in terms of wavelength).

About the Winegard balun. It can be installed either way, phase relationship flips with balun reversal, matters not much on single antennas. For stacking, to maintain phase relationship, one must take this into consideration.

Antenna rotators can be very useful tools in troubleshooting.

--------------------------------

'Above the top' will be easier explained after a few more photos.

--------------------------------

This is a photo of the antennas that replaced the CM-1110.

.



.


The only objective of the VHF antennas was to better receive WKYT (at that time RF channel 13), 74 miles distant, 2-edge diffraction according to TVfool.

The configuration:

- Two Winegard YA-1713, stacked
- Combiner; Winegard CC-7870
- Spacing; 43 inches (was varied +/- 18 inches while watching Signal Meter)
- Mast length; 10.5 feet, ~ 7.5 feet above tower.
(Made from heavy duty top fence rail (SS-20, ~1 & 3/8 inch outer diameter)

- Channel Master antenna rotator moved inside tower for stability.
- Final Preamp, Channel Master CM-7777 (original), a WG-3700 was tested
- All cables RG-6, custom installed connectors.

In 2010, WKYT changed RF channels from VHF 13 to UHF 36, so the YA-1713s were not of much use after that.

The configuration stayed in place for approximately a year, until ~mid 2010.

.

[tripelo]

The following image shows an 8-bay antenna that was purchased in 1970. Pretty sure it is Channel Master, probably a precedent to the popular ’original’ CM-4228. The physical dimensions and construction are different. Note the differing transmission line feeding the right and left 4-bays, it extends downward. The antenna demonstrated about 0.5 dB better gain on low to mid UHF channels than the popular ‘original’ CM-4228. No comparison was made for upper channels.

That antenna was hit by a tornado in 1971, breaking a whisker (upper right). The tornado destroyed surrounding buildings, along with the tower and other antennas on it.

Note: People lost their lives and many homes were destroyed in that tornado.

The 8-bay whisker was repaired and it was placed in storage until 2010.



Mid 2010, the antenna was installed to receive channel 22 WCTE at 65 miles distant. At that time WCTE was transmitting 57 kW ERP. TVfool showed the path diffraction as 2edge.



For convenience and shorter preamp feed length, the 8-bay was mounted upside down.

The preamp was the UHF section of the CM-7777 (VHF portion in use for Yagis), using an 'inside' balun (with silicone waterproofing).

The Yagis and the CM-4251 already had their separate cables and were combined with UVSJ behind the TV. So, behind the TV, the 8-bay channel 22 signal was separated from CM-7777 coax with another UVSJ, then added back to CM-4251 UHF signals via a Channel Master Jointenna.

Although the reception was very good for WCTE, channel 22, this antenna configuration lasted only a few months.

.