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HD8200U Mod.

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Old 02-02-2018, 12:40 PM   #1  
Sev
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Arrow HD8200U Mod.

I was going through HDTVPrimer.

When I noticed a mod for the CM3761 using separate leads.
There appears to have been a noticeable difference in gain between around channels 10-46.

I am considering removing the board and replacing it with 2 older Channel Master baluns.
Run 2 preamps and then combine in the house behind the power sources.

Has anybody done attempted something similar.

http://hdtvprimer.com/antennas/CM3671mod.gif

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Old 02-03-2018, 08:47 AM   #2  
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No give up 60's tv antenna???
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Old 02-03-2018, 03:23 PM   #3  
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I would use an A/B switch as trying to combine them after some unknown coax lengths, and a (what type of?) combiner, could cause some serious hair loss.

After 60+ years working with almost every type of antenna, the saying goes "If it ain't broke, then don't mess with it".
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Old 02-03-2018, 04:21 PM   #4  
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Quote:
Originally Posted by Terryl3 View Post
I would use an A/B switch as trying to combine them after some unknown coax lengths, and a (what type of?) combiner, could cause some serious hair loss.

After 60+ years working with almost every type of antenna, the saying goes "If it ain't broke, then don't mess with it".
I was going to use a Hollands GHS-2Pro

My other option is to run 110 up the pole and put the power units in weather tight boxes. Coax length could be efficiently controlled at that point.
I already have exterior power below the antenna.
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Old 02-03-2018, 06:35 PM   #5  
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Quote:
I noticed a mod for the CM3761
It's 3671, not 3761.
Quote:
I am considering removing the board and replacing it with 2 older Channel Master baluns.
Run 2 preamps and then combine in the house behind the power sources.
Quote:
I was going to use a Hollands GHS-2Pro
If you are going to modify a $200 antenna that doesn't need a mod, please use the correct device. That is the wrong device to combine a UHF antenna with a VHF antenna; you should use a UVSJ.

Last edited by rabbit73; 02-03-2018 at 06:44 PM..
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Old 02-03-2018, 07:20 PM   #6  
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Quote:
Originally Posted by rabbit73 View Post
It's 3671, not 3761.

If you are going to modify a $200 antenna that doesn't need a mod, please use the correct device. That is the wrong device to combine a UHF antenna with a VHF antenna; you should use a UVSJ.

It's a $60.00 dollar antenna. Tripped over it.

Ooops
Fumble fingers Rabbit. A little dyslexia. Good catch. At least the graph is correct.

Yes I know I should not be using a full spectrum splitter.
I have been looking for a Holland or a Pico
Cant seem to find any anywhere.

If anybody has a line on some or a private stash I would be pleased to be pointed in the correct direction.

Last edited by Sev; 02-03-2018 at 08:22 PM..
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Old 02-03-2018, 10:20 PM   #7  
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Quote:
Yes I know I should not be using a full spectrum splitter.
You should not be using ANY kind of 2-way splitter to combine a UHF antenna with a VHF antenna.

Isn't the 8200 a UHF antenna and a VHF antenna all-in-one that you want to separate?

You should be using a UVSJ, UHF-VHF-Separator-Joiner.

https://www.radioshack.com/products/...itter-combiner

The Radio Shack description isn't very accurate, but it really is a UVSJ UHF/VHF combiner, AKA UHF/VHF Diplexer. I have measured it and used it.







or
https://www.antennasdirect.com/store...Combiners.html



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Last edited by rabbit73; 02-03-2018 at 10:24 PM..
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Old 02-04-2018, 08:25 AM   #8  
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Quote:
Originally Posted by rabbit73 View Post
You should not be using ANY kind of 2-way splitter to combine a UHF antenna with a VHF antenna.

Isn't the 8200 a UHF antenna and a VHF antenna all-in-one that you want to separate?

You should be using a UVSJ, UHF-VHF-Separator-Joiner.

https://www.radioshack.com/products/...itter-combiner

The Radio Shack description isn't very accurate, but it really is a UVSJ UHF/VHF combiner, AKA UHF/VHF Diplexer. I have measured it and used it.




or
https://www.antennasdirect.com/store...Combiners.html


Good morning Rabbit.

That is correct.
I am trying to minimize noise and loss in the system and increase gain.

You are familiar with my terrain challenges.

I recently replaced my Radioshack VU-190xr with the 8200.
Unfortunately the 190xr appears to be performing better than the 8200.
Position and elevation have not changed.

My problem station is supposed to be FOX WEMT RF 38. Which I am just out the shadow of the mountains.

However my VHF-Lo and HI have been giving my problems ever since.

The only thing that changed aside from antenna design is the 190XR uses a balun and 8200 uses a circuit board.
As has been noted. Ferrite baluns have a better VHF response with loss at the upper end of the UHF.

The way the leads come into the Winegard, makes it very simple to mod.
I can wirenut my NOS CM9444 baluns in without making any changes to the leads.

My understanding is that Holland USVJ specs claimed .5 of insertion loss. And its return loss was also low.

I have been told that while they work, both the Radioshack and Antenna's Direct products lack in sensitivity and create both noise and loss.
I am assuming that information is good as it is coming from an electrical engineer that has been DX'ing for quite a while and testing components as well.

I will be replacing my RCA TVPRAMP1R preamp.

I am going to be powering the VHF side with a new Winegard AP-3700.
I am hoping to have a new New Winegard AP-8275 in the near future to power the UHF side with. Otherwise I will be looking to get either a Kitztech or Tin Lee.
I'll be using Belden quadshield RG6. Approx 50 feet of coax.
It will be less once I relocate my router.

At that point. Everything is going to be routed through a SiliconDust unit and converted to WIFI.
Thus eliminating any insertion loss by splitting the coax any further.
If I could I would put the Silicondust unit right on the mast and run Shielded Cat 5e aerial to the router.
Another consideration is doing 2 direct drops to 2 silicondust units
and not combining the antenna's all. Go directly to WIFI. Use an A/B switch if needed.

I recently started doing some DX'ing.
I am on the rabbit ears map.
https://rabbitears.info/tvdx/many_tu...61A9AC/tuner0/

The Silicondust unit is being utilized to send the information. It is scanning continuously. I am also using software that monitors changes in signal strength and quality which can also be used to monitor changes in reception when individual components are changed.

The Silicondust unit can be used instead of those Sedelco's we talked about for finding the area with strongest signal strength.
With a long enough coax lead I can traverse the property with an antenna and watch changes in signal strength in real time.

My concern is to not put a weak link in the middle of the middle of the design that nullifies any benefits gained.

If I can find a Holland or Blonder tongue UVSJ it would be much preferred. Looks like everybody is hording them though.

As always. If anything I have stated is incorrect please let me know.

Last edited by Sev; 02-04-2018 at 08:41 AM..
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Old 02-04-2018, 10:10 AM   #9  
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[QUOTE=
I recently replaced my Radioshack VU-190xr with the 8200.
Unfortunately the 190xr appears to be performing better than the 8200.

The Radioshack vu-190xr and the 210xr were good performing antennas. The durability of the radioshack antennas have always come into question, but as far as gain they were as good as any other vhf uhf combo antenna. I am sure antennacraft built those antennas for Radioshack and neither off them will get any love on this forum.
Keep in mind you are only getting other peoples opinion on this forum, it is by no means the Law.
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Old 02-04-2018, 11:04 AM   #10  
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Quote:
Originally Posted by TVantenna Man View Post
I recently replaced my Radioshack VU-190xr with the 8200.
Unfortunately the 190xr appears to be performing better than the 8200.

The Radioshack vu-190xr and the 210xr were good performing antennas. The durability of the radioshack antennas have always come into question, but as far as gain they were as good as any other vhf uhf combo antenna. I am sure antennacraft built those antennas for Radioshack and neither off them will get any love on this forum.
Keep in mind you are only getting other peoples opinion on this forum, it is by no means the Law.
Everybody has their personal bias towards products.
What is important that the data on the actual components is accurate.
One persons bad experience is not necessarily an indictment of an entire product line.

The 190xr is still in good shape.
If I see a 210xr on a pole somewhere I might pick it up.
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Old 02-04-2018, 03:09 PM   #11  
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Well, Sev is now a DXer. That explains your concern about loss before the preamp. Any loss before the preamp directly subtracts from the antenna gain, just as the preamp NF directly subtracts from the antenna gain. Distribution loss after the preamp is not as damaging because it is a later term in the Friis system noise figure formula.
https://en.wikipedia.org/wiki/Friis_formulas_for_noise
Quote:
An important consequence of this formula is that the overall noise figure of a radio receiver is primarily established by the noise figure of its first amplifying stage. Subsequent stages have a diminishing effect on signal-to-noise ratio. For this reason, the first stage amplifier in a receiver is often called the low-noise amplifier (LNA).
Quote:
I have been looking for a Holland or a Pico
Cant seem to find any anywhere.
I was also looking for them, not for low loss but because they pass DC to the VHF port. NLA, no longer available.

I did find some old MACOM UVSJs, made before there was Pico-Macom that have very low loss, because they have fewer components. I measured the UHF loss for one, along with three other currently available UVSJs.





more later
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Last edited by rabbit73; 02-04-2018 at 07:59 PM..
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Old 02-04-2018, 03:29 PM   #12  
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Yes looks like that 8200u ant what it's cut out too be know the antnnacarft ANTENNAs good ANTENNA but cheaply made vhf hi &low
And no one is going too bring back the hi&low vhf ANTENNA manufactures tell me no so antnnacaraft is gone so can I copie the hi&low vhf Am Antnnacaraft antenna that I have and sell them but they will be made out of copper!! So will I be able too do that
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Old 02-04-2018, 04:13 PM   #13  
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Quote:
Originally Posted by rabbit73 View Post
Well, Sev is now a DXer. That explains you concern about loss before the preamp. Any loss before the preamp directly subtracts from the antenna gain, just as the preamp NF directly subtracts from the antenna gain. Distribution loss after the preamp is not as damaging because it is a later term in the Friis system noise figure formula.
https://en.wikipedia.org/wiki/Friis_formulas_for_noise


I was also looking for them, not for low loss but because they pass DC to the VHF port. NLA, no longer available.

I did find some old MACOM UVSJs, made before there was Pico-Macom that have very low loss, because they have fewer components. I measured the UHF loss for one, along with three other currently available UVSJs.





more later
LOL.
Fledgling. DX'er.
We will see how far it goes.
However it is a good way to tune the system.

So ahhhh. You dont happen to have any spares laying around per chance?
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Old 02-04-2018, 04:24 PM   #14  
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Yes$ 65dollars +shipping
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Old 02-04-2018, 05:30 PM   #15  
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I was curious about the performance of the MCM UVSJ and compared four UVSJs for UHF insertion loss:

MCM 33-2230
Radio Shack 15-2586
Antennas Direct EU385CF-1S
Macom (Old)

For the first measurements, I used a Blonder Tongue HAVM-1UA Frequency Agile Modulator as a stable signal source, and a Sadelco DisplayMax 800 Signal Level Meter. The modulator puts out an analog signal; I used the video carrier for each channel. The Sadelco meter has 0.1 dB resolution.



I was having a problem getting consistent measurements. The Sadelco meter has a built-in calibration reference and at certain intervals will correct its readings. This was difficult for me to deal with when making 0.1 dB resolution measurements, so I switched to my Sadelco 719E meter that has a panel meter with wide 1 dB divisions in the center of the scale that allows me to interpolate to the nearest 0.1 dB.

The Sadelco 719E is on the left; the DisplayMax 800 on the right:



I used the red divisions and the second scale -10 to +20 dBmV.



I would read that as +2.8 dBmV.

To make a measurement, I first connected the modulator to the meter with an F-81 adapter and took a reading. I then substituted the UVSJ, UHF and common ports, for the adapter for the second reading.

There was an attenuator at the output of the modulator and at the input of the meter to try to keep the line "flat" (low SWR).



The loss figures are underlined.

The MCM 33-2230 does have a higher insertion loss that might make a difference if your marginal signals are at the "Digital Cliff."

The Macom UVSJ has very low loss because it has fewer components.

My equipment isn't "lab grade," but it is the best that I can afford.

Quote:
So ahhhh. You dont happen to have any spares laying around per chance?
Yes, I can measure one or two for UHF and VHF insertion loss and other band rejection.
http://www.hollandelectronics.com/ca...-Diplexers.pdf

I would need your name and address by PM to be able to send it/them to you, if the complete measurements are satisfactory.

Power failure here now; more later.
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Last edited by rabbit73; 02-04-2018 at 06:46 PM..
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