Sirio Mag-145PL. Not impressed.

[Mudslinger]

I bought one of these a while back, and as it was sat unused in my room I gave it to my brother.

He has been using it on and off fitted to his car for the past 6 months, and always had issues with putting out a decent signal, so he gave it back to me today to have a look.

I was shocked at how much corrosion was inside the thing, and this was causing a poor connection between the coax braid and the metal part of the base, leading to a very poor or completely missing ground.

It also appears that it could have been assembled wrong at the factory. On the top there are 4 screws, one does through an eyelet which is soldered to the braid, and this screws into a brass captive nut with is inside of the plastic top. The other end of one of these is fixed to the magnet with a screw to connect it to ground. However the one which the eyelet was connected to wasn't the one which was connected to the metal part of the magmount.


Hopefully that makes sense, and could help someone who has issues with one of these. I am shocked at poor quality from Sirio, especially as my 30 + year old Limpet is still going strong despite much abuse.

[The Collector]

I think Original45 or 108***** has gone into detail on the flaws with this particular mag-mount, as well as what they did to overcome the issues. A quick search may find the topic/s, unless they come on and kindly repeat their repair/improvement process again.

[Mudslinger]

I did have a look but I couldn't find the threads.

They could be a really good mount if only they were built better.

[Alan Pilot]

I bought one last year.
Don't know why but i took the bottom cover off before i ever used it and it was in a bad way.
Glad i did as it would have been a bad experience trying to start up again after 25/26 years off the radio.
As i am typing this i am thinking why did i do that strange but glad i did.

[ch25]

I had many ML145 mag mounts to fix in the past.
Corrosion and broken coax inside mostly.
But nothing wrong with antenna itself.

[InTheClouds]

Mine worked, I was not blown away though, I used it with a 4000 hi power on it. I think I expected a little much for a mag mount antenna mind you.I have a cheap CRT large base mag now (though it is not my preferred means of antenna mount on a vehicle), it seems to work as well as the Sirio which is double the price.

As a rule though I do like Sirio kit, good quality usually, maybe you just got a "Friday afternoon assembled mag mount", bad luck.

They don't mess around it seems like a serious hi tech set up at the factory :

[Mudslinger]

My brother has tried to use this mount again today, and despite it having been taken apart and repaired correctly it is still giving very poor performance.

There seems to be an issue with it coupling to ground, SWR is good on the 5000 antenna, (and an ML145 which we also checked) but the signal output is terrible. Electrically it checks out ok.

[InTheClouds]

Trying to think this through and cannot think of why that might be. Is it choked at all ? 5 turns balun style. Middle of roof or positioned elsewhere on the vehicle ? The pattern can be very distorted if not central. Mount on rear and you get a bit of a fling forward (polar response) and opposite side and mount at front flings it backwards and to the opposite side. I guessing you know this already though.

Long shot but you are not in a null spot ? Or the person you are getting signal checks from.

My (static) mobile antenna is rear mounted and I find this polar pattern very significant at least in my install, people behind me generally
see lower signal from me and seem low signal coming in to me. You can use this directionality to your advantage. It is not quite turning your
car into a beam but it is noticeable to me and so you can orient your vehicle where you want to try getting to. West to a net ? Or East for some DX.

[Mudslinger]

Middle of the roof, no chokes and no nearby obstructions.

He is going to buy a new one and then see how that checks out.

When I say it was putting out a poor signal it really was. 5 watts in and he was one mile away from me on high ground so no obstructions and he was hitting me S1-2

[original45]

Yup theirs issues that need sorting. Even tried fitting new rg8 but swr wasn't as good so reverted.
Once their improved they seem to be good at least mine and the antennas are now.

Also noted mine all swr lower not in centre of roof but 12" either side of centre

[InTheClouds]

Mine worked pretty well when I first had it, was making 15 mile contacts quite easily at low land areas SSB 15 watts. Manged much further on hills. It worked OK. But i could never go back to whips after using base antennas out and about. In my experience they can have a 2-6 S point difference, that is a HUGE difference. So I was never blown away by mag mounting.

I cannot understand why they would not work, Sirio know their stuff. Maybe contact them and ask they seem quite good as responding to questions.I managed to break my 145 mag base by accident, don't ask.

[The Collector]

Acdident my arse. You got so fed up with it not making contacts that you threw it out your bedroom window.

You're on the 17th floor

[Mudslinger]

Just had another look at this. I am pretty sure that the problem is due to the foil layer which you stick onto the bottom. The glue on it isn't allowing it to give a good connection to the raised part in the middle beneath the mount. Without that the coupling is going to be greatly reduced.

Judging by the corrosion on all of the other parts though the metal looks to have come from a recycled Lancia Beta.

[InTheClouds]

Had it been stored in a bad place ? That is the only other thought for the corrosion ? I guess there is only one way to find out, get another one or another 7inch large one and see how it goes. Frankly I fast went off the idea of mag as a way of mounting.

When I go on nets my mobile mirror mount antenna was talking to people 25 - 160 miles away with a bit of conditions and regularly 50miles all aound. That suggests it is working quite well. Mag mounting is compromised mounting, it makes a less well performing antenna system. Clearly it should be working better than yours is, replace it and enjoy the new performance.

One good thing with CB stuff is it not that expensive for the majority of people, especially later in life second time around.

I am a bit an*l about how I feed it though,, super 8, nicely choked and shortest possible length. I really put effort into making it a solid install, it receives my home QTH QRM up perfectly at S7. Well better to laugh than cry I suppose.

[Mudslinger]

It was in pefect condition before it went on the car and was on and off (mostly off) for the matter of a few weeks.

I do have another magmount (Donkies years old Limpet) and that works perfect. Obviously not with the same antenna though as the limpet is 3/8

Do President sell a better quality PL mag mount I wonder?

I agree a better mount such as a hole in the roof would work better, but I am not taking a drill to my BMW.