Pager on approx 148.400MHz gone mad.

[VK4OX]

I don't know if any-one else in the Brisbane area can hear this, but one of the pagers on approx 148.4MHz has spurious emmissions every 500kHz stretching from 144MHz to 153MHz. This has been getting progressively worse over the past few months but it has really gone berserk this afternoon. I don't work repeaters but surely they must be getting hammered by this qrm? It is now affecting the weak signal end of the band in QG63.

73, Adrian VK4OX.

[VK3DXE]

Time for a call to ACMA?

That'd suck big time.

[VK4TIM]

Having a listen around here I can hear what could be a weak pager on 148.3625, the usual pagers on 148.5625 and 148.6375 and one on 148.8125.
Nothing strange here (although I'm monitoring on the spectrum analyser at the office). You might have to get a bearing on the problem transmitter.

My guess is that if it's putting out spuries every 500kHz or so the caps in the PA driver supply have failed, causing the supply to oscillate, modulating the PA first stages.
Classic failure, seen it many times before.

[VK3BA]

If it were you or I causing interference to other services, the ACMA would be down our neck in a flash.

So, report it accordingly. It's about time some of these paging operators cleaned up their act.

Cheers,

[VK4OX]

Hello Tim, VK4TIM,

Thanks for info..I'm using an old Watkins Johnson wide band receiver capable of tuning from 88-230MHz..Analog dial, so frequency read-out not that accurate, but it does have the signal monitor that is capable of "seeing'" +/- about 1.5MHz of spectrum at its widest span.

The rogue pager has settled down again..What I see now is sidebands of multiple carriers ranging out to about +/-300kHz when some of the pagers go off..However, there is one particular pager that is producing sidebands of multiple carriers out to about +/- 600kHz when it goes off.

My qth, Bald Knob, is about 500 metres west of the Wilkes Knob commercial microwave/radio site... I don't get any other interference from this site, or the Bald Knob TV translators site located about 800m east of me.

After I placed about 30dB of attenuation in the antenna cable to the WJ rx, I could turn the log periodic antenna and get a direction... It would appear that the pager is due east of me and probably on the Wilkes Knob site. I am prepared to put up with an increase of 2dB in my noise floor in my 144.100MHz weak signal receiver when this particular pager go off but when it went beserk this arvo I was getting s9 rubbish all over the bottom end of 2m..This pager does go beserk from time to time.

I'd be interested in what you see on your SA when you point your beam north and look at 148.500MHz, +/-.

73, Adrian VK4OX.

[VK3AIF]

I had a similar problem to this one a couple of years ago and discovered it was from mixing products from two paging systems and only occurred when both were transmitting simultaneously, I hit the acma database only to find that one of the frequencies was not listed as allocated in this area so I could not determine if the transmitters were co-located or not. Armed with this information I emailed the acma and reported the problem and furnished the offending frequencies, this was followed up with a phone call in due course and I was informed that the licenses were "Australia Wide", which I would have thought would still show up on their database? Anyway the person on the other end of the phone was not very sympathetic to my plight and suggested it was probably a receiver problem at my end and was going to leave it at that.

The good news is it went away shortly after and has not returned so I know not whether it healed itself or there was other work done as nothing was changed here. I have not monitored the frequencies recently to see if they are both still active or not either.

I hope this was of some help.

Dave
VK3AIF