Sirio HP4000 body mount?

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26OD004
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Sirio HP4000 body mount?

Post by 26OD004 »

Hi,

I'm looking at body/panel mounting a Sirio HP4000 to a van roof and I'm struggling to find any suitable SO-239 mounts. The van roof is not flat, it has ridges so IIRC I have about 120mm in the centre of the roof to fit a mount. Fitting in the centre of the roof is a must not just for equal radiation pattern but for OCD reasons :lolno:

I see Sirio have a panel mount available, but this is SO-239 for the antenna to a Sirio DV plug, I have tried but I can't find a power rating for this "DV plug" online but I know the DV27 antenna I last used this connector on (many years ago) only had a 100W rating, I would be looking to run a bit more than 100W hopefully.

I see lots of 3/8th to SO=239 mounts available but I want SO-239 on the roof and SO-239 or N type or anything that can handle a few hundred watts one the inside. I've always had RF feedback issue's when running power with mag mounts which is why I want to body mount.

I really don't want to ditch the HP4000 antenna as it's always been a great performer but why design a 1000W PEP antenna when there doesn't appear to be a 1000W PEP body mount available for it?
The Collector
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Re: Sirio HP4000 body mount?

Post by The Collector »

I would guess that the most power you can run to an antenna depends on:

* the inner core thickness of the co-ax

* the melting point of the solder on all joints

* the coil windings of the aerial.

I should imagine it'll take a few hundred watts without getting too hot. An ultra-low SWR would be beneficial ;)

I've got a so-called "heavy-duty" SO mount through the roof on my car (so it can withstand 70+mph against a tall aerial without deforming the metal roof) but 4 watts is all I'm ever likely to run through it!
26OD004
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Re: Sirio HP4000 body mount?

Post by 26OD004 »

The Collector wrote: 19 Feb 2022, 10:56 I would guess that the most power you can run to an antenna depends on:

* the inner core thickness of the co-ax

* the melting point of the solder on all joints

* the coil windings of the aerial.

I should imagine it'll take a few hundred watts without getting too hot. An ultra-low SWR would be beneficial ;)

I've got a so-called "heavy-duty" SO mount through the roof on my car (so it can withstand 70+mph against a tall aerial without deforming the metal roof) but 4 watts is all I'm ever likely to run through it!
Thanks for the reply, just managed to find and order one of these which should be just the ticket

https://moonrakeronline.com/rfs-s2-heav ... re=default

Is this what you are using?
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Re: Sirio HP4000 body mount?

Post by The Collector »

Just watch with some of those beehive-type mounts. If they've got a large, triangular-shaped "washer" that grips the metal underneath the hole, the 3 slightly-angled points can slightly deform the metal at those points if the metal is thin and the washer is tightened too much.

Edit - just clicked on the other pic's. That one's got a multi-pointed grip washer design so it shouldn't deform the roof panel as easily.




I've got one like this on mine below.
A big, fat, top washer/ nut spreads the load. I used enamel paint on the drilled hole, allowed it to dry and then used a decent polyurethane body panel sealant around the hole before tightening the mount onto it. It should hopefully never leak. I think the description is wrong on the below, but the picture is of the mount I used:

https://www.ebay.co.uk/itm/CB-Antenna-A ... 635-2958-0
26OD004
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Re: Sirio HP4000 body mount?

Post by 26OD004 »

I remember the DV27 mounts having the triangle shaped washer.... and what they did to the biscuit tin if you overtightened :D , good shout.

It's going onto a 6 year old works van that's a bit beat up already so I'm not too concerned about the roof as long as if worst came to worst I could fit a grommet and seal it up water tight again. The van will be driven until it's dead so no need to worry about resale value.

I did think of fitting some sheet steel/ali on the underside of the roof to spread the load out a little but the reviews on the mount I bought complain of the threads not being long enough if the roof is a little on the thick side, so looks like I'll have to fit it and hope for the best.

What's the worst that could happen? I turn the van into a pickup? :lol: :lol: :lol:
The Collector
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Re: Sirio HP4000 body mount?

Post by The Collector »

...or it leaks and you have a mobile aquarium ;)

1-9 for a carp-y lol.

If you can push the roof panel and it flexes, then another layer of metal would be a good idea if you're going to use a Firestik or something substantial, but for a base-loaded aerial you should be okay.
Saying that, if you whack any low branches near to the coil, then the panel could possibly kink a little.
Even an extra millimetre of thickness would help, say about 8 inches wide, but if you can't, you can't.
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Re: Sirio HP4000 body mount?

Post by The Collector »

26OD004 wrote: 21 Feb 2022, 22:01 I remember the DV27 mounts having the triangle shaped washer.... and what they did to the biscuit tin if you overtightened :D , good shout.

It's going onto a 6 year old works van that's a bit beat up already so I'm not too concerned about the roof as long as if worst came to worst I could fit a grommet and seal it up water tight again. The van will be driven until it's dead so no need to worry about resale value.

I did think of fitting some sheet steel/ali on the underside of the roof to spread the load out a little but the reviews on the mount I bought complain of the threads not being long enough if the roof is a little on the thick side, so looks like I'll have to fit it and hope for the best.

What's the worst that could happen? I turn the van into a pickup? :lol: :lol: :lol:
Any updates on this at all? :)
26OD004
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Re: Sirio HP4000 body mount?

Post by 26OD004 »

The Collector wrote: 19 Mar 2022, 19:25
26OD004 wrote: 21 Feb 2022, 22:01 I remember the DV27 mounts having the triangle shaped washer.... and what they did to the biscuit tin if you overtightened :D , good shout.

It's going onto a 6 year old works van that's a bit beat up already so I'm not too concerned about the roof as long as if worst came to worst I could fit a grommet and seal it up water tight again. The van will be driven until it's dead so no need to worry about resale value.

I did think of fitting some sheet steel/ali on the underside of the roof to spread the load out a little but the reviews on the mount I bought complain of the threads not being long enough if the roof is a little on the thick side, so looks like I'll have to fit it and hope for the best.

What's the worst that could happen? I turn the van into a pickup? :lol: :lol: :lol:
Any updates on this at all? :)
Yes, but not what you would expect :lol:

Injector went on the van, so had all 4 replaced. Since then it's been losing coolant, been back in and tested the coolant which shows evidence of exhaust gasses absorbed into the coolant. They think there is a crack in the head or head gasket has gone. Either way, new engine or new van required {bnghd}

Just waiting for the powers that be to decide what they want to do with it, so I've held off installing anything for now...
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Re: Sirio HP4000 body mount?

Post by The Collector »

Ahhh... yes...I see :)

Not worth bothering with until you know what's what.

I've got myself a Sirio Megawatt 4000 now, big buggers these 4000's aren't they ;) I really wanted a 5000 "Rigid" but can't get one over here.
26OD004
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Re: Sirio HP4000 body mount?

Post by 26OD004 »

I have tried a fair few mobile antennas over the years, modulators, dv's, sirio ml-145, firesticks etc. The 4000 is the best performing antenna that I've tried that I'm comfortable to drive around with. I did compare it to a 9 foot tank whip (while stationary obviously) and the whip just edged it, but not by much. IIRC when I changed from the ML-145 to the 4000 There was at least 1-2 s point improvement. It also would take all the power a KL500 could throw at it with no ill effects, but yes, they are rather tall :lol:

Used to make my little vauxhall astra look like a dodgem :D
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Re: Sirio HP4000 body mount?

Post by The Collector »

That's the main problem with big aerials, it's aesthetics vs performance. A 3 or 4ft twig looks good, but to get out well, you really need over 5ft. But, then you get a swinging/pendulum action whilst mobile, especially around town, the received signal bouncing around from s2 - s7 etc. Static-mobile's a different matter of course.

I used to run around in my Escort mk1 with a Tagra t40 on a boot mount which was 5ft (very similar to a K40 but with a tapered whip which helped against the whip swinging so badly), or a centre-loaded Modulator on a 6" magmount on the roof and even a 2ft dial-a-match which I could attach to the gutter-mount on my Cavalier mk2 through the window whilst driving :)
Although I no longer use CB, I have a PNI165 aerial (like ml145 but 200mm bigger, was only £12 delivered) and now the MW4000 should I ever need to go mobile. I doubt I ever will but the MW was in amongst a job-lot of stuff I recently bought.
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