DPD Aerial experiment

[GlynH]

Hi Glyn, as it sounds as though you're looking at a fair run of co-ax, I'd definitely suggest going for the Elad mast head amp., I don't know anything about the Kuhne or whether it's intended for exterior use .

Hi Jon,

I'll pass on the Elad thanks...

I had decided some time ago which pre-amp I wanted and the Kuhne is widely regarded as the Rolls Royce of pre-amplifiers...

It is a mast-head design and as such is intended to go right there...

http://www.kuhne-electronic.de/en/shop/143_Vorverstaerker/article:342_KU_LNA_1090_A_TM

Regards,
-=Glyn=-

[CoastGuardJon]

Hi Glyn, that's good to know then, in the description :

Features

ESD protection at preamplifier input

Built-in bias tee for remote power supply via coaxial cable 

The first is obviously good, but the second I found confusing "Built-in bias tee", as to whether it's for outside use.

Let us know how you get on, I've still to buy a pre-amp, so you could influence my purchase!

I've just looked at the description again, and see it says "Case" German silver installed into a water-tight case  and a bit further down, it's referred to as mast-head.

[Canonjohns40D]

Hi Mark Right to answer your questions. I am in Bangor along the South Shore of Belfast Lough. My aerial the supplied one sits inside a double glazed window which faces North. Both Belfast City (BHD) and Belfast Aldergrove (BFS) sit west, of my location. Almost behind my line of sight, if you can imagine literally along my window line. Between me and BHD are the Holywood/Craigantlet Hills so I see BHD landing Aircraft down to about 1500ft before they dip below the hill. BFS sits behind Black Mountain and I see their landing aircraft to about 1200ft. The problem facing South South West is the house and surrounding property. From the shore I would as you suggest see clear to the Isle of Man and therefore could/should reach into Wales with the radarbox. However where it is sited now I get out to just beyond the Ilse of Man. I would get around 280 to 340 Aircraft recorded on My log Daily though I have topped 400 on a couple of occassions usually depending on the transatlantic routes in use on any given day. These are picked up within my Polar Diagram area which was attached to the earlier post.

Today I tried the DPD aerial inside the same window where the supplied aerial sits. The polar diagram is similar to that of the supplied aerial it seems to fall short in some areas. This may be as it has only run for about 12 hours so I will continue with it tomorrow also. So far today 403 Aircraft have been logged this is within my normal range although towards the higher end.

Polar diagram supplied aerial attached for information
John

[GlynH]

Hi Glyn, that's good to know then, in the description :

Features

ESD protection at preamplifier input

Built-in bias tee for remote power supply via coaxial cable 

The first is obviously good, but the second I found confusing "Built-in bias tee", as to whether it's for outside use.

Let us know how you get on, I've still to buy a pre-amp, so you could influence my purchase!

I think there may have been a little something lost in German->English translation...

As I understand it the Bias Tee is a seperate item that can be installed anywhere on the coax - obviously inside in the dry as it is powered by a PSU!

This then 'injetcs' the voltage needed to drive the pre-amp through the coax - no other control wires needed.

The pre-amp is designed to work outside at the mast-head before any signal losses are inmposed by the cable.

Hope that helps.

Kind regards,
-=Glyn=-

[GlynH]

Today I tried the DPD aerial inside the same window where the supplied aerial sits. The polar diagram is similar to that of the supplied aerial it seems to fall short in some areas. This may be as it has only run for about 12 hours so I will continue with it tomorrow also. So far today 394 Aircraft have been logged this is within my normal range although towards the higher end.

John

You really need to get that Watson outside John...quick!

Mine pulls in in around 2500 aircraft every day according to MyLog - and that's without a pre-amp!

The design of the Watson I believe does lend itself to being susceptible to ESD IMHO so care will need to be taken...

That's the mainy reason I am considering the Kuhne...

Kind regards,
-=Glyn=-

[Canonjohns40D]

Hi Glynn it is all ready to go I'm relying on a friend though to locate it for me. Hopefully this weekend as the weather is forecast to be good. Where are you located? I get local traffic to the two belfast Airports and some around West of scotland. The bulk is then the transatlantic stuff overflying me.

John

[Canonjohns40D]

Day two with the DPD aerial in a similar indoor position to where the supplied aerial was sited.

Yesterday I logged 403 aircraft this is the high end of my usual numbers with the suppplied aerial. Today I have 460 logged. The polar diagram looks similar to that of the supplied aerial but does have some extension in length North and North East the direction my window faces. The distances to the South (through the house) on the polar diagram are shorter with the DPD just getting out beyond the IOM. So far I'd say the DPD and the supplied aerial are receiving out to similar distances and recording about the same numbers of aircraft. As already stated this is an inexact science as the Atlantic routes may well be the influencing factor this past two days. Certainly today I had more USAF aircraft than yesterday also.

I had hoped the DPD would be sited outside tomorrow but this seems unlikely now. Should this remain the case i'll continue with it in it's temporary indoor location. Further updates to follow.

Polar diagram attached for info.
John

[GlynH]

I think people underestimate the efficiency & coverage of the supplied antenna - mainly because the short cable length effectively 'ties' it within spitting distance of the RB hardware which means it usually ends up on a desk, shelf or at best a window sill.

I keep referring back to testmonkey's experiment (where is he anyway?) where he shows his polar diagram using the supplied antenna from his house and then on his car roof sat on top of a local beauty spot (hill).

The coverage he achieved there puts many base-mounted antennas with masthead pre-amps & expensive coax to shame...

http://www.airnavsystems.com/forum/index.php?topic=1324.0

In fact it rivals my own coverage and I am 460 feet asl with the 1m long, 1 inch thick Watson antenna mounted on the top of a 17 foot pole at the gable end of my house!

By way of comparison here is a screenshot I posted last July - in fact testmonkey had much better coverage West than I did;

http://www.airnavsystems.com/forum/index.php?topic=1324.0

That little antenna must be the bargain of the century - it's not the size that counts you know! ;^)

Kind regards,
-=Glyn=-

[Canonjohns40D]

Hi I agree Glynn this experiment has shown me the supplied aerial is very effective. it is located inside double glazed windows yet performs well. I am happy with the 300 plus aircraft i get daily from this aerial.
I want to further enhance the hobby though and that is why I'm keen to have an external aerial. As i feared it wont be erected this weekend either now. Just for information I have Westflex 103 cable atttached to the DPD with a patch lead to the radarbox. The 20metres of cable remain coiled for this indoor experiment. What the last couple of days have show me is if anything just how good the supplied aerial is. It will remain a useful tool when eventually the outdoor aerial is up. I can see it travel to any location I am at for plane spotting, holidays etc etc.

John

[Canonjohns40D]

Hi 343 aircraft logged by the DPD today, day 3. The polar diagram (attached) remains similar but has extended slightly in a couple of places. sadly the aerial will not be erected outdoors this weekend again. I'll keep it up indoors and see how it continues to perform.

The skys were pretty quiet over Northern Ireland this evening perhaps attentions lay in another direction? Congratulations Ireland on the their Grand slam achievement.

John

[Canonjohns40D]

Hi Day 4 and the DPD mounted temporarily indooors continues to perform at about the same level as the supplied antenna. 384 aircraft have been logged today so again within my usual traffic amounts. The Polar diagram (attached file for info) has again stretched a little.

I hope the DPD will be outside this week and then a real test can begin. In the meantime if it isn't boring you all to death, I'll continue running it in the indoor position.

John

[Falcon]

Hi Day 4 and the DPD mounted temporarily indooors continues to perform at about the same level as the supplied antenna. 381 aircraft have been logged today so again within my usual traffic amounts. The Polar diagram (attached file for info) has again stretched a little.

I hope the DPD will be outside this week and then a real test can begin. In the meantime if it isn't boring you all to death, I'll continue running it in the indoor position.

John

Hi John,

Thanks for the update.

The fact that you are hooked up to 20 meters of cable is very promising. If I want to have some flexibility with my antenna installation and get it in the right spot I need to use close to 30 meters. I wonder how that will work out if I use something like LMR400 http://www.timesmicrowave.com/content/pdf/lmr/22-25.pdf.

There is also another cable in the US called BuryFlex from DavisRF www.davisrf.com that is recommended.

Regards,
Falcon

[Canonjohns40D]

HI Falcon sorry but when it comes to the technical stuff it's time for me to seek not offer advice. I got the Westflex 103 as recommended but as regards other types well!! Perhaps someone else will respond with useful advice.

John

[Falcon]

HI Falcon sorry but when it comes to the technical stuff it's time for me to seek not offer advice. I got the Westflex 103 as recommended but as regards other types well!! Perhaps someone else will respond with useful advice.

John

No problem.

I was going to mention (but didn't) that I was thinking of starting a thread for cables and maybe another for antennas if I don't see another thread that is very specific on those topics. External antennas and cable are each are a very important part of a successful setup.

The antenna that comes with the Radarbox performs very well but I haven't heard anyone mast mounting one of them on the top of a house.

Your setup looks like its going to do very well.

[Canonjohns40D]

Hi falcon have a look at this topic on the forum titled, Improve RadarBox Antenna Instead of Buying 3rd-Party. it is what you are referring to and may be of help.

John