Q From Haynes, Hi Line diversity question

[John Robins]

Originally Posted by JohnDotCom

Colin,
The Side window "elements" on Tourer are the TV aerials. Other "elements & Shark Fin" are the Radio, and Sat Nav.

John , tourers without t.v. have etched side window(s) so I guess they must be for the radio .

[JohnDotCom]

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?

[David3807]

Originally Posted by Keith

There may be side effects, I get interference and reception loss in my hi-line CDT with the HRW on that I don't get in the later non diversity equipped ZT

|Suppose all the heated elements are working ??

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.

[SD1too]

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.

[SD1too]

Originally Posted by Keith

... it would be relatively easy to retrofit the diversity system if it is worthwhile and I am not sure it is...

One would need the missing coax and mini connectors a diversity amp the four way connector lead to the hrw or improvise with a bit of DIY.

The only thing I don't have are the chokes to go in the earth leads on the bottom two elements of the HRW I would need to find some suitable values to give it a try

THE MISSING COAX & MINI CONNECTORS:
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!

[Departed]

Originally Posted by SD1too

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.

Interesting. I am aware that the IF itself is 10.7MHz. Discussions with Radio and antenna manufacturers and Engineers (including the one who developed the 75s antennas) in the past have always been that the system functions in the way I decscribed, and I had assumed that the actual signal was an IF product (not the IF itself).

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.

[Keith]

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

[Keith]

Originally Posted by David3807

|Suppose all the heated elements are working ??

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.

Yep HRW is fine there is a thread or a howto on this somewhere
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

[Keith]

Originally Posted by JohnDotCom

Perhaps something on these lines Keith but I know there is much better stronger ones out there.:
http://www.maplin.co.uk/module.aspx?...&doy=21m3#spec

Vor ist das glas koppelung bestandteil mein heir

or maybe that should be
Wo der Glaskoppelung Bestandteilsir ist

[Departed]

Originally Posted by Keith

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?

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.