Mounting my db8

[maypo]

Approximately 8+ft above my roof is my very old Radio Shack antenna and a very old RS rotator.(tripod, riser mast,rotator and mast) I just bought an antennas direct DB8 and the mast mounted above the rotator is not long enough for mounting the DB8.
I would like to get the DB8 up higher if possible and wondering just how much higher would be a safe bet. i will replace the upper mast with a longer one and move up in diameter a bit too. How much is too much...

[JoeAZ]

Greetings Maypo,
I assume you have removed the old antenna. The DB8 is a fairly large
antenna, with significant loading and as such, I would not go beyond
5 feet for the mast above the rotor. With the wind, Ice and snow you
can expect, I would say that 5 feet is a safe bet. You best and most
difficult way to increase height would be to extend the mast BELOW
the rotor. Then, guy wires would be necessary.

[ADTech]

Check the rotor's specifications for the maximum length of the stub mast. Light-duty rotors will severely restrict the length of that mast so as to limit the lateral loading on the bearings of the output shaft. If you can, use a thrust bearing to maximize the durability of the rotor unless you have one that's beefy such as an amateur radio model. If your rotor is an inexpensive one, keep the stub mast as short as you can while still mounting the DB8 so it clears the rotor and any guy wires.

[maypo]

Is the wind load on this really more than my old type really long double beam?
Thanks to all for the info.

[rickbb]

Yes it's more, how much I don't really know. But the older beam styles were flat and thin as far as wind goes, the bow tie styles, (like the DB8), are like a sail on a boat sticking up against the wind.

[maypo]

It mostly open fine wire grid work unlike a sail but ill take your word for it.

[Nascarken]

So true on that DB8,and way over priced to
The antennas Direct 91xg is the best ANTENNA for uhf cents that is what it is for
And the solied SIGNAL Hdb91 that has a beem with pattern of 60,is all so a good
Uhf only antenna and when using an mast mount amp like the channel master 7777
Amp with its 32BG in mass or CT state you should be able to receive BROADCASTING TOWER 80miles away day or night time in good or bad weather conditions.
And with the HDB91,with its 60with Beem if pointed right no rotor should be used??

[wizwor]

Originally Posted by Nascarken

So true on that DB8,and way over priced to
The antennas Direct 91xg is the best ANTENNA for uhf cents that is what it is for And the solied SIGNAL Hdb91 that has a beem with pattern of 60,is all so a good Uhf only antenna and when using an mast mount amp like the channel master 7777 Amp with its 32BG in mass or CT state you should be able to receive BROADCASTING TOWER 80miles away day or night time in good or bad weather conditions.

And with the HDB91,with its 60with Beem if pointed right no rotor should be used??

The 91XG has a relatively narrow beam compared to the DB8. When I had a DB8, I was able to receive VHF as low as real channel 11. You can also take off the reflectors if you have strong signals in front and in back -- almost omnidirectional reception.

But it is a sail. No doubt about that. At least it is inarticulate so, it will bounce back and I never noticed much impact on reception when it was dancing. Besides the high vhf reception, I loved that the DB8 was great when the trees were moving around...I suppose due to the large collection area.

[Nascarken]

not the HDB91 by solid signal it has a beam with of 60
And when the wind blows with a channel master 7777AMP
No dropouts lol

[ADTech]

Solid Signal botched the "specifications" of the UHF Yagi. Here's the specifications from the Chinese manufacturer: http://www.qiaohua.com/products/av-91xu.htm All they would have had to do was copy them correctly....



They also botched the "specifications" for the 8-bay. They just copied the BW from the 4-bay and 2-bay variations and anyone who understands how 8-bay antennas work as compared to 4-bay antennas will immediately see the error. The Chinese manufacturer, in this case, provided no product information for their 8-bay offerings: http://www.qiaohua.com/products/AV-0948DT.htm Here is the 4-bay variant: http://www.qiaohua.com/products/AV-0948.htm

[Nascarken]

Well I dount think so I have used both the HDB91&the Antennas Direct 91st at the same
Location same higth and with a channel master 7777AMP 80miles away and
Even in bad weather conditions single of 80percent and no dropouts
And 70miles an hour winds in Springfield Massachusetts and Block iland
Sound NY the only thing is the HDB has one less element frum the ANTENNA Direct
91xg has that one more element and I do not think it makes a difference at all!!!