Conflicting behavior between Dr. HD 1000 Combo and TV on Terrestrial signal?

[itsgc]

Hello Folks,

First time poster and definitely a newbie when it comes to troubleshooting tv reception etc.

I have a Dr. HD 1000 Combo signal meter (Dr.HD 1000 Combo).

It is supposed to be able to pick up DVB-T signals and can show a lot of data for each mux / channel.

I have moved into a new home relatively recently and i am trying to understand the current antenna install. I have not gone on the roof yet as it's not incredibly accessible.

Here is the problem:

- Sony Bravia TV receives several channels ok so i am inclined to think the antenna is installed and aimed at least partially correctly
- The signal meter errors out with an "Antenna Overload" error as soon as i connect the antenna feed.
- There seems to be no DC across the cable ( i figured there might be some phantom feed for an amplified somewhere that was upsetting the meter)
- Checking resistance on the coax cable coming from the antenna with a multimeter shows almost a short, ~1.x ohms. Is this expected for a working DVB-T antenna over a regular coax cable?!
- Figuring the signal could be too strong, i bought some cheap attenuators but even with 3 + 6 + 10 (19!) dBs of attenuation the meter still says "Antenna Overload"
- I have another antenna feed on the upper floor, fed by a separate antenna which does not yield the same error but also doesn't seem to pick up any channel either (i am unsure if this latter cable is correctly wired into the second antenna but the cable sleeve colors and the entrypoints into the building match for both). I have not tested this second feed with a TV yet.

- My main questions are:
- has anybody worked with this signal meter before and/or ran into this "antenna overload" message and successfully got the meter to work?
- What should i expect on a multimeter / oscilloscope out of a TV antenna working correctly in terms of inbound DC / resistance etc?

I realize i may have not provided the correct information and apologies if this is a complete beginner request and possibly poorly asked.

Thank you in advance for any help you might be able to provide!

 

[Terryl]

Are you looking a terrestrial TV signal or a satellite signal?
Are you in a single family home or multiple dwellings side by side? (row housing)
If your looking at a TV signal are there any satellite dishes on this home? If so you might be looking at a combination of the TV antenna and and satellite dish.
A dead short on the coax is not normal, there should be some resistance on the antenna matching baulin. (if there is one)
Some photos of the antennas would help, or the model/type of antenna.

 

[a33]

- The signal meter errors out with an "Antenna Overload" error as soon as i connect the antenna feed.
...
- Checking resistance on the coax cable coming from the antenna with a multimeter shows almost a short, ~1.x ohms. Is this expected for a working DVB-T antenna over a regular coax cable?!

The "short" could be perfectly normal for a terrestrial antenna (dvb-t/dab). (Edit: dipole antenna)

In that case: the antenna must have absolutely no voltage from the receiver (usually 5 V), which is only meant for an optional amplifier near the antenna! So check that that is switched off, in the settings.

I know nothing about the DrHD1000.


By the way: Welcome to the forum, @itsgc !


Greetz,
A33

edited.

 

[Terryl]

Most terrestrial TV antennas that I have worked with (in the past 50 years) are either 300 ohm's (flat twin lead) or 75 ohms (coax) impedance, the 300 ohm down lead is hardy directly used now days, most have a 300 ohm to 75 ohm balun transformer, (external or internal to the antenna) now with out a impedance meter the 75 ohm side when measured with a DVM at the final end of the coax should be at least 3 to 5 ohms, .2 to .5 ohms for the balun and the rest is the approximate DC resistance of the coax. (center conductor to shield up and back down)

It would be nice to see what type/brand of antenna he has.

 

[Channel Hopper]

Ask a neighbour if you can connect your meter to their aerial, see if the results are different to your system.

 

[rolfw]

I don't have this meter, but Antenna overload would normally happen if you are trying to send a voltage up to the antenna, like it would in satellite mode. If you are definitely in DVBT mode, then check that there isn't a 12v supply to antenna toggled when there is no masthead amplifier.. I doubt it'll be too much signal, as that would just show a messed up spectrum. Have you retuned both of the TVs and did they give you a choice of regions?

 

[itsgc]

Hello! sorry i was traveling for work yesterday. I'll post some pics in a moment.

Are you looking a terrestrial TV signal or a satellite signal?
Are you in a single family home or multiple dwellings side by side? (row housing)
If your looking at a TV signal are there any satellite dishes on this home? If so you might be looking at a combination of the TV antenna and and satellite dish.
A dead short on the coax is not normal, there should be some resistance on the antenna matching baulin. (if there is one)
Some photos of the antennas would help, or the model/type of antenna.

- this would be a terrestrial TV signal
- single family home, semi-detached. Antennas are on my own property and they are not shared.
- There are not sat dishes on on the building itself and none that share any infrastructure (cables, mixers etc.) with these TV antennas. I have a dish in the garden but it is entirely separate, i installed it.
- photos incoming!

By the way: Welcome to the forum, @itsgc !

Thank you <3

I don't have this meter, but Antenna overload would normally happen if you are trying to send a voltage up to the antenna, like it would in satellite mode. If you are definitely in DVBT mode, then check that there isn't a 12v supply to antenna toggled when there is no masthead amplifier.. I doubt it'll be too much signal, as that would just show a messed up spectrum. Have you retuned both of the TVs and did they give you a choice of regions?

I only tested one TV, i retuned it and automatic tuning picks up over 100 channels. Channels looks fine except BBC seems jumpy sometimes (i get some frame rate freezes etc. once in a while even without rain/heavy wind).

The meter shows 0V being pushed out and i have the option of sending 5V or 13V which i did not use, so unless the meter is broken i don't think i am sending volts up.

ok thank you so much everybody for your help, i will take some pictures now and come back.

 

[itsgc]

Hello folks, here are the pictures and sorry for the delay.



The antenna installed lower on the pole is the one giving me the errors on my signal meter but also the one giving me actual reception

 

[Channel Hopper]

Hello! sorry i was traveling for work yesterday. I'll post some pics in a moment.



- this would be a terrestrial TV signal
- single family home, semi-detached. Antennas are on my own property and they are not shared.
- There are not sat dishes on on the building itself and none that share any infrastructure (cables, mixers etc.) with these TV antennas. I have a dish in the garden but it is entirely separate, i installed it.
- photos incoming!


Thank you <3



I only tested one TV, i retuned it and automatic tuning picks up over 100 channels. Channels looks fine except BBC seems jumpy sometimes (i get some frame rate freezes etc. once in a while even without rain/heavy wind).

The meter shows 0V being pushed out and i have the option of sending 5V or 13V which i did not use, so unless the meter is broken i don't think i am sending volts up.

ok thank you so much everybody for your help, i will take some pictures now and come back.

Is that SD or HD channels ?

 

[Joolz]

Welcome to the forum.

As the 1000 combo only has one antenna connection (ANT In) I assume you are pressing the UHF Spectrum or the DVB-T/T2 button to make your test. If you use the SAT Spectrum of DVB S/S2 buttons the meter will try to power up an LNB on that single antenna input and you will get a Antenna overload message (Current, not signal).

 

[Terryl]

That puck shaped object on the antenna's is the matching transformer, (baulin coil) the two butterfly and U shaped elements are the active ones, they are setup as a 300 ohm active balanced system, these signals are then fed into that puck shaped object and converted to a 75 ohm unbalanced signal. (center fed coax with grounded shielding)

It looks like that antenna system has been up there for some time, there could be a crack in the coax insulation somewhere and water has got in. (guessing on my part)

Is there a ground block (or blocks) somewhere on the coaxes ?? if so there could be some corrosion on one or more "F" connectors.

I wish I was there I could help you out.

 

[John]

Welcome to the forum.

As the 1000 combo only has one antenna connection (ANT In) I assume you are pressing the UHF Spectrum or the DVB-T/T2 button to make your test. If you use the SAT Spectrum of DVB S/S2 buttons the meter will try to power up an LNB on that single antenna input and you will get a Antenna overload message (Current, not signal).

Good shout - The bottom antenna looks like a cheap 'Contract 18' aerial with just a simple direct coax inner + braid coax connection to the two connection terminals within the dipole loop. If as joolz says, the meter is putting out a voltage up the coax the meter will be seeing practically a dead short and therefore an error message. Coax dressing to the two antennas looks a lot to be desired also and could be a future coax failure.

 

[itsgc]

Hello all, thank you so much for all your suggestions and help!!

I was doing several things wrong, plus i was dealing with some issues of the install itself.

• Feed voltage needed to be disabled in *both* the DVB-T and DVB-S menus! I assumed that given you can hear a relay click when you select either menu, that it was only active when you entered each, but nope.
  Voltage is out all the time unless you disable it separately in both menus.
  
  
• Once i had disabled feed voltage in the DVB-S menu as well, i stopped getting the Antenna overload messages! However i wasn't getting any reception.
  
  
• The cable is *really* poor quality and has almost no shield strands and they are incredibly brittle. I don't think my F termination was that good. I guess the TV was either less fussy or something else was going on when i connected it to the TV.
  
  
• Once i fixed both, i focused on just getting the BBC Mux on Channel 32 working. When checking a single channel, the meter gives you the option of setting the DVB-T flavor (1 or 2).
  If the wrong flavor is selected, the meter doesn't show *any* of the RF stats!
  I figured i was gonna be able to first confirm if there was any signal at all _and then_ fuss with the encoding/DVB flavor to get an image but nope.
  Either you have the correct one selected or the meter shows nothing.
  
  
• After some further finagling i finally got some "green" signal on the led bar at the top of the meter. Once i got that, i was able to do a full scan and i found about the same amount of channels on the signal meter as i did on the TV.

And TV signal stats for good measure

Is that SD or HD channels ?

They are SD channels, i don't seem to be getting HD channels at all.

Welcome to the forum.

As the 1000 combo only has one antenna connection (ANT In) I assume you are pressing the UHF Spectrum or the DVB-T/T2 button to make your test. If you use the SAT Spectrum of DVB S/S2 buttons the meter will try to power up an LNB on that single antenna input and you will get a Antenna overload message (Current, not signal).

Turns out this meter spits out LNB voltage even when the DVB-T/UHF menu is selected, unless you explicitly disable it in the DVB-S menu as well.

It looks like that antenna system has been up there for some time, there could be a crack in the coax insulation somewhere and water has got in. (guessing on my part)

Is there a ground block (or blocks) somewhere on the coaxes ?? if so there could be some corrosion on one or more "F" connectors.

I wish I was there I could help you out.

Thank you so much Terryl <3 Yes, this house was empty for a long time and that Antenna is decades old at least.

I have a spool of good quality 7mm cable that i can swap this ancient dodgy run with. Now that i have a working meter i might also consider either using the upper antenna that looks to me to be more recent and in better condition OR buy a new Yagi.

Thank you all for letting me unravel this mystery!

 

[Channel Hopper]

They are SD channels, i don't seem to be getting HD channels at all.

From that you may find the neighbours (better aerial or pointing in a different direction ) have the answer.