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21st March 2007, 18:49 | #11 |
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21st March 2007, 21:23 | #12 |
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Mmmm. The wiring Diagram showed it as TV most strange, will check on my return and Post the Rover Diagrams & Locations.
Im sure I read it right but will now double check. Sorry if wrong Information has been given in this case. I will stand in the Corner & recite Double Check before Writing! I now wonder why 2 sets of aerials one either side would be required for Radio? |
21st March 2007, 22:02 | #13 | |
Posted a thing or two
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I posted sometime ago with exactly same problem and have never got around to looking behind the trim for things and checking earths etc as suggested. However I do have a small break in one element and cleaning the whole rear window inside with a decent glass cleaner improves the radio reception no end. |
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22nd March 2007, 11:01 | #14 |
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Technical point
lowedb said:
"The second connection is an output from the radio to the antenna amp, so the amp knows what frequency the radio is tuned to." Here's a small, and I hope interesting, technical detail. Whatever frequency your radio is receiving, the radio immediately converts it into its "intermediate frequency", or I.F. as it's known in the trade! This is a standard frequency used by all radios (except perhaps 'digital' types of which I know nothing) and 10.7 MHz comes to mind. The miniature coax lead sends the strength of the IF from the radio to the "aerial isolator" which then selects another rear screen aerial element if necessary. So the aerial isolator (or antenna amp) cannot and does not know the frequency to which the radio is tuned; it receives only a 10.7 MHz signal of varying level. Hope this clarifies and does not confuse. |
22nd March 2007, 11:26 | #15 | |
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There's a coax lead with connectors illustrated on the MGR EPC, part number XUD 100603 (up to VIN 245553) and XUD 000240 (from VIN 245554) which might be what is needed. I stress the word "might". DIVERSITY AMP: This is still available as XUC 100 751 (Isolator, aerial, high specification) originally specified up to VIN 240701. THE 4-WAY CONNECTOR LEAD TO THE HRW: This comes already attached to the HRW and is believed to be part no. CQB 102011 (to VIN 219626) or CQB 000220 (from VIN 219627). Do not be tempted by CQB 000350 which definitely doesn't have four leads attached, despite being described on the EPC as "full diversity". THE CHOKES TO GO IN THE EARTH LEADS ON THE BOTTOM TWO ELEMENTS: Not sure about these, but there's a good chance that they'll come pre-attached to the HRW as well. So later cars without functioning diversity can probably be converted, for about £500! |
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22nd March 2007, 12:11 | #16 | |
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However, I've just spoken to our antenna Engineer, who had been told the same, but he did some digging, and it seems you are right that it's not as I (or he) believed. However he tells me that it's not the IF at a varying level either (he had a scope on it and there was no RF. He tells me that its a low level signal at close to DC. I can only assume it is a voltage corresponding to signal strength. Sorry if this is getting a bit deep. Now I've added this bit as a result of reading Fuba's patent on the scandiv system, which it appears is different from the system my colleauge here knows about. link: http://www.freepatentsonline.com/7127218.html The signal is indeed the IF. But it's not as explained to me the frequency that is being monitored, but the interference present. By switching antennas and looking at the interference present, it can pick the best antenna. So by monitoring the IF it doesn't know what the radio is tuned to, but is effectively monitoring the signal quality. Again, sorry if this is a bit deep, but maybe it will be interesting to someone other than me. You learn something every day. Last edited by Departed; 22nd March 2007 at 12:40.. Reason: Looked up Fuba scandiv system info |
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22nd March 2007, 13:51 | #17 |
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Coo it sound so impresive I simply must wire mine up after all!
Won't cost me £500 I just need two suitable RF chokes (or whatever the black bulges are in the two earth leads from the HRW) Lowed can you recommend a suitable value? Pic of Diversity Amp |
22nd March 2007, 13:55 | #18 | |
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It is down to the proximity of the leads to each other iirc like you I haven't bothered to investigate yet as it is not that annoying and you can easily turn off the HRW It does tend to increase the chance of TMC signal loss though |
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22nd March 2007, 14:02 | #19 | |
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or maybe that should be Wo der Glaskoppelung Bestandteilsir ist |
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22nd March 2007, 17:47 | #20 |
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Yes they are chokes, and not particularly high value. From memory (it was a few years ago) they were a few turns (maybe 5 or so) of heavy gauge enamelled copper wire around a ferrite core. The most important thing is that the wire is thick enough to add little resistance into the rear window circuit, and high enough impedance at FM frequencies to stop the signal going to ground.
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