Sirio 827 5/8wave

[gmham]

Anyone here use the Sirio gpe27 5/8wave vertical antenna ? Have not long purchased one myself and I now notice that the tuning chart supplied seems to differ from the one available on the internet ?


26.4 mhz = 850mm for the 5/8 wave version.
27 mhz = 642mm
27.185mhz = 600mm
27.500mhz = 487mm
28.000mhz =340mm
28.500mhz =183mm
29.000mhz=15mm

The tuning table supplied with my own Sirio gpe27 5/8 wave and also available on the internet shows :

26.700mhz = 900mm
27.000mhz =816mm
27.185mhz =760mm
27.500mhz =664mm
28.000mhz =512mm
28.500mhz =354mm
29.000mhz =204mm
29.500mhz =54mm

Very strange ?! Anyone any ideas ?!
Thanks.john

 

[JAF0]

Sorry but I'm done with Sirio antennas, except for repairing the BROKEN ONES people give me.
They're just too fragile, especially the top of the NV4K!

I just helped a friend install a new NV4K last December and even though the highest recorded wind gusts in his area were only 58mph, the top is now BENT at a 35 degree angle

What I've done in the past to repair this type of problem is to add a 4" long piece of solid aluminium rod that fits nicely down inside the hacksawed top tube of the NV4K and drill down into that solid aluminium rod so as to fit a 48" tuning whip from a Wilson trucker 2000. There, no more bendie bend.

Now why didn't Sirio do that from the factory?

I also shorten the rest of the top 2 tubes of the antenna until tuned to the correct length of approx 321".

It's up to you how you want to secure the whip into the solid aluminium, some simply drill fairly snug, then laterally smash with a hammer, or cross-drill and use set screws.

I like to drill the hole in the solid aluminium rod slightly under the whip diameter then use opposing heat/cold to expand the aluminium by heating it while dry-icing the (end-bevelled) whip to shrink it, plus drilling a pressure-release hole at the base of the downward-drilled hole.

I then slam the chilled whip quickly into the heated aluminium hole in the top of the solid rod by tapping them together using (also chilled) vice-grips to hold the whip and hit the vice-grips with a hammer.

I use nolox as both a lubricant and deoxidizer.

After the two become one, when they slowly return to ambient temperature, they are inseparable.

I also mark the whip at 1.25" with a permanent marker so I know the whip has fully seated.

Y M M V!

 

[Shadetree Mechanic]

Its possible that the design has changed slightly causing the tuning to be different. Sometimes manufacturers try to use as many common parts as they can between antenna models. I would use what ever came with the antenna.
Chris 73

 

[Shadetree Mechanic]

Sorry but I'm done with Sirio antennas, except for repairing the BROKEN ONES people give me.
They're just too fragile, especially the top of the NV4K!

I just helped a friend install a new NV4K last December and even though the highest recorded wind gusts in his area were only 58mph, the top is now BENT at a 35 degree angle

What I've done in the past to repair this type of problem is to add a 4" long piece of solid aluminium rod that fits nicely down inside the hacksawed top tube of the NV4K and drill down into that solid aluminium rod so as to fit a 48" tuning whip from a Wilson trucker 2000. There, no more bendie bend.

Now why didn't Sirio do that from the factory?

I also shorten the rest of the top 2 tubes of the antenna until tuned to the correct length of approx 321".

It's up to you how you want to secure the whip into the solid aluminium, some simply drill fairly snug, then laterally smash with a hammer, or cross-drill and use set screws.

I like to drill the hole in the solid aluminium rod slightly under the whip diameter then use opposing heat/cold to expand the aluminium by heating it while dry-icing the (end-bevelled) whip to shrink it, plus drilling a pressure-release hole at the base of the downward-drilled hole.

I then slam the chilled whip quickly into the heated aluminium hole in the top of the solid rod by tapping them together using (also chilled) vice-grips to hold the whip and hit the vice-grips with a hammer.

I use nolox as both a lubricant and deoxidizer.

After the two become one, when they slowly return to ambient temperature, they are inseparable.

I also mark the whip at 1.25" with a permanent marker so I know the whip has fully seated.

Y M M V!

I just put up a NV4k, That is good to know. I will have to take a good look at mine when I tip it down tomorrow.

 

[JAF0]

Anyone here use the Sirio gpe27 5/8wave vertical antenna ? Have not long purchased one myself and I now notice that the tuning chart supplied seems to differ from the one available on the internet ?


26.4 mhz = 850mm for the 5/8 wave version.
27 mhz = 642mm
27.185mhz = 600mm
27.500mhz = 487mm
28.000mhz =340mm
28.500mhz =183mm
29.000mhz=15mm

The tuning table supplied with my own Sirio gpe27 5/8 wave and also available on the internet shows :

26.700mhz = 900mm
27.000mhz =816mm
27.185mhz =760mm
27.500mhz =664mm
28.000mhz =512mm
28.500mhz =354mm
29.000mhz =204mm
29.500mhz =54mm

Very strange ?! Anyone any ideas ?!
Thanks.john

Sorry about my rant completely forgetting to include info relevant to your post, but the top of the GPE-27 is the same silly 3mm solid aluminium rod, which bends so easily in relatively light wind, as has the NV4K.

 

[gmham]

Thanks so much guys appreciate the advice.will do as suggested and use the size given for 28.5mhz within the set off notes supplied with my antenna at time off purchase just find it strange this second set off tuning details for the same antenna.no one else running this particular vertical ?

 

[Shadetree Mechanic]

If Marconi is around, he might be familiar with the variations of this antenna.

 

[M0GVZ]

The lengths are merely guides, a starting point to get you going. Every installation will be different.

Everything from how high you have it above the ground, the soil conductivity, how close adjacent buildings are etc will affect the tuning of the antenna.

 

[gmham]

Okay yep totally appreciate that just wondered why Sirio had two different tuning tables for the exact same antenna ? Anyway after a conversation with Sirio in Italy last week it's seems the website has changed back to the original tuning table ie. the correct one !

 

[JAF0]

The lengths are merely guides, a starting point to get you going. Every installation will be different.

Everything from how high you have it above the ground, the soil conductivity, how close adjacent buildings are etc will affect the tuning of the antenna.

I'd want the antenna to be precisely the correct length for the upper 18 or so feet to be right at a 1/2 wave at the target frequency, then use the supplied gamma match and tap point for tuning your unique installation.

not that it matters much, it'll probably break off within a year or so