Radio reception issues with double din

[Teflon]

Grateful for the thoughts of the forum on this. I have one of Seans "double din" sets, and have some issues with the radio reception. It wasn't too bad to start with, but since fitting an aerial splitter to feed both the main unit and TMC from the same aerial, the reception has worsened (to be expected I suppose).

Anyhow, this morning I set about checking that my aerial amp is working as it should:

• Firstly, I simply disconnected the feed to the aerial amp at the back of the car whilst the radio was on, and noticed hardly any difference in reception. Putting the feed back made a few crackles, but not much else. Seems like no power to the amp then.
  
• I next checked for power using one of those electrical screwdrivers (with the light in the handle and some crocodile clips). I put the blade of the driver into the end of the power feed, and the clips onto the connector of the amp - the bulb in the handle did not light. So:
  
• I then (just to be sure) connected a length of wire direct from the battery, and placed the other end on the aerial amp's terminal. Still nothing. So:
  
• To check my connections, I clipped the electrical screwdriver to the end of my improvised power lead, and "earthed" the screwdriver tip on the cars body work. The bulb lit up, confirming power. I then put the screwdrivers tip onto the power feed terminal of the amp. Nothing. No lit bulb, no improvement in reception.

So, does this mean that my aerial amp is simply not working? Am I right in assuming that the screwdrivers bulb should have lit up when connected between the amp and it's power feed? Or is it simply that the later (non diversity) aerial amps are not really up to the job?

Any and all thoughts would be appreciated.

Cheers,

Cliff

[HarryM1BYT]

Grateful for the thoughts of the forum on this. I have one of Seans "double din" sets, and have some issues with the radio reception. It wasn't too bad to start with, but since fitting an aerial splitter to feed both the main unit and TMC from the same aerial, the reception has worsened (to be expected I suppose).

Reception is bound to be a little worse, because the splitter is unlikely to be an impedance matching type. The antenna expects 75 Ohm being presented to it but is seeing something less than 40 Ohm and the signal is being shared between the two anyway - but it should still work reasonably well. Could the splitter perhaps be faulty?

If you have a multi-meter - Between the centre terminal base of the Y and each arms centre terminal you should see zero Ohms (or a steady 30 to 40 Ohms if it is a matching type). Between the outer of any plug to the outer of any other plug, you should also see zero Ohms (or something very close to zero).

The older radios would be fitted with a little trimmer in the back, so you could peak up the reception to better match the feed impedance.

To check my connections, I clipped the electrical screwdriver to the end of my improvised power lead, and "earthed" the screwdriver tip on the cars body work. The bulb lit up, confirming power. I then put the screwdrivers tip onto the power feed terminal of the amp. Nothing. No lit bulb, no improvement in reception.


So, does this mean that my aerial amp is simply not working? Am I right in assuming that the screwdrivers bulb should have lit up when connected between the amp and it's power feed? Or is it simply that the later (non diversity) aerial amps are not really up to the job?

The clip on the test lamp needs to be connected to a good ground, the lamp should then light when connected to any point which has +12v on it. If, with your system switched on, it doesn't light with the probe on the supply to the amp, there is a problem.

I have not tried it with the amp working versus not working, but I would expect it to make a very dramatic difference. My previous Ford had its amp unplugged when I got it and reception was dire - only the very strong signals could be heard. Once I had found the fault, reception was terrific.

Personally - I don't think the amp (or maybe the antenna) is as good as it could be. My last car used all of the rear window heater to provide an antenna and it worked superbly well.

[Teflon]

Thanks for the response. It does seem as if there's something wrong with the aerial amp. With the splitter fitted, the radio is all but useless and putting power to the amp seems to make no real difference at all. In fact, on a couple of occassions it made it worse!

Time to look for a news (second hand?) aerial amp I think.

Cliff

[CDTi]

Originally Posted by Teflon

Thanks for the response. It does seem as if there's something wrong with the aerial amp. With the splitter fitted, the radio is all but useless and putting power to the amp seems to make no real difference at all. In fact, on a couple of occassions it made it worse!

Time to look for a news (second hand?) aerial amp I think.

Cliff

I have a spare amp somewhere.

Interested?

[Teflon]

Yup!

Is it the later (non diversity) type? If so, PM me with how much etc, and I'll be most grateful.

Cheers,

Cliff

[CDTi]

PM on the way.

[HarryM1BYT]

Originally Posted by Teflon

Thanks for the response. It does seem as if there's something wrong with the aerial amp. With the splitter fitted, the radio is all but useless and putting power to the amp seems to make no real difference at all. In fact, on a couple of occassions it made it worse!

Time to look for a news (second hand?) aerial amp I think.

Cliff

Did I read somewhere on this forum that there might be an issue with the connections between amp and the screen antenna?

[Teflon]

Thanks Harry, I'l check the connections later this morning.

Cliff

[David Lawrence]

Originally Posted by Teflon

Grateful for the thoughts of the forum on this. I have one of Seans "double din" sets, and have some issues with the radio reception. It wasn't too bad to start with, but since fitting an aerial splitter to feed both the main unit and TMC from the same aerial, the reception has worsened (to be expected I suppose).


Anyhow, this morning I set about checking that my aerial amp is working as it should:

• Firstly, I simply disconnected the feed to the aerial amp at the back of the car whilst the radio was on, and noticed hardly any difference in reception. Putting the feed back made a few crackles, but not much else. Seems like no power to the amp then.
  
• I next checked for power using one of those electrical screwdrivers (with the light in the handle and some crocodile clips). I put the blade of the driver into the end of the power feed, and the clips onto the connector of the amp - the bulb in the handle did not light. So:
  
• I then (just to be sure) connected a length of wire direct from the battery, and placed the other end on the aerial amp's terminal. Still nothing. So:
  
• To check my connections, I clipped the electrical screwdriver to the end of my improvised power lead, and "earthed" the screwdriver tip on the cars body work. The bulb lit up, confirming power. I then put the screwdrivers tip onto the power feed terminal of the amp. Nothing. No lit bulb, no improvement in reception.

So, does this mean that my aerial amp is simply not working? Am I right in assuming that the screwdrivers bulb should have lit up when connected between the amp and it's power feed? Or is it simply that the later (non diversity) aerial amps are not really up to the job?

Any and all thoughts would be appreciated.

Cheers,

Cliff

My thoughts on this are based on my own troubles with reception. What I found was that if you are tuned in to a pretty strong signal then you won't notice much change in the signal with the amp connected or not connected. To check it you really need to tune in first to a weaker signal. With a weak signal you will notice a difference when you turn the amp on or off.

An electrical screwdriver with a light is usually for detecting mains voltages so I wouldnt expect it to light up from 12v unless its an automotive one.

As mentioned by someone else to test the supply with a bulb you need to connect between the supply lead and chassis, and not to the amp terminal, because the amp will present a high resistance so the bulb wont light.

My own reception was poor with the standard amp, but the amp was working, just poor. To resolve is I bought an in line booster called something like Celcus AAN2002 ??? Something like, cant remember now.

Before going down that route I also experimented with a halfords screen aerial which gave some small improvement over the standard aerial and amp. They are about £12. It can also be fitted down the side of the rear screen and covered up by the cladding so you cant see it.

One idea to help you may be to use the standard amp direct in to the aerial socket for the radio, and then use a Halfords separate aerial for the TMC socket. Should give you a much stronger signal to both than by using a splitter. If you wanted to go even further you could then also add a booster to the one for the radio.

The TMC in my experience is a bit hit and miss anyway as it is only broadcast over a few stations, so if you have porr reception on that station you can be driving for miles before you pick anything up. I think it is also broadcast on Rock FM and Heart FM.

[HarryM1BYT]

My thoughts on this are based on my own troubles with reception. What I found was that if you are tuned in to a pretty strong signal then you won't notice much change in the signal with the amp connected or not connected. To check it you really need to tune in first to a weaker signal. With a weak signal you will notice a difference when you turn the amp on or off.

An electrical screwdriver with a light is usually for detecting mains voltages so I wouldnt expect it to light up from 12v unless its an automotive one.

As mentioned by someone else to test the supply with a bulb you need to connect between the supply lead and chassis, and not to the amp terminal, because the amp will present a high resistance so the bulb wont light.

My own reception was poor with the standard amp, but the amp was working, just poor. To resolve is I bought an in line booster called something like Celcus AAN2002 ??? Something like, cant remember now.

Before going down that route I also experimented with a halfords screen aerial which gave some small improvement over the standard aerial and amp. They are about £12. It can also be fitted down the side of the rear screen and covered up by the cladding so you cant see it.

That is a reasonable alternative.

One idea to help you may be to use the standard amp direct in to the aerial socket for the radio, and then use a Halfords separate aerial for the TMC socket. Should give you a much stronger signal to both than by using a splitter. If you wanted to go even further you could then also add a booster to the one for the radio.

Putting amps in series is never good practise, because the second one will only amplify the noise along with the signal. Better to deal with the poor reception at source, either the poor amp or the poor reception antenna.

The TMC in my experience is a bit hit and miss anyway as it is only broadcast over a few stations, so if you have porr reception on that station you can be driving for miles before you pick anything up. I think it is also broadcast on Rock FM and Heart FM.