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Old 26th Feb 2020, 1:47 pm   #1
gezza123
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Default RCA AR88D. Wrong station on shortwave band 2.

Hi guys
I am getting Radio City Talk that is normaly on 1548KHz,
on shortwave 3096KHz on my AR88D.
Is anyone else getting this or am I about to develope a fault.

This is crystal clear and better reception than 1548KHz.
thanks guys for any information
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Old 26th Feb 2020, 1:49 pm   #2
merlinmaxwell
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Default Re: Wrong station on shortwave band 2

What is 1548 x 2... 3096!
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Old 26th Feb 2020, 1:54 pm   #3
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Default Re: Wrong station on shortwave band 2

Thanks merlinmaxwell
I checked that I thought it might have creeped up the band,
but everything else is ok'
thanks gezza123
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Old 26th Feb 2020, 2:00 pm   #4
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Default Re: Wrong station on shortwave band 2

Surely that suggests something wrong with aerial alignment? Second harmonic should be rejected or at least be so low down in the noise as to not matter? I don't know the AR88 but are there any rejecters that might need adjusting?
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Old 26th Feb 2020, 2:07 pm   #5
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Default Re: Wrong station on shortwave band 2

It may be that the second harmonic of the transmitter is escaping more than expected. 3MHz isn't a part of the spectrum that the average listener devotes much attention to, so a transmitter shortcoming/maladjustment might go for a while before it's noticed. I recall that the otherwise quiet 30-32MHz region often had the second harmonic of 19m transmissions present, sometimes very clearly, though generally at low signal strength.
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Old 26th Feb 2020, 3:57 pm   #6
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Default Re: Wrong station on shortwave band 2

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Originally Posted by turretslug View Post
It may be that the second harmonic of the transmitter is escaping more than expected..
Used to find this at BBC Washford on the Doherty transmitters if the l/4 carrier-peaker network went off tune slightly, the second harmonic would shoot up and put BBC Radio 1 right in the fishfone emergency channel on 2178kHz. We would soon get a call from the Portishead radio station!

Don't know what sort of transmitter Radio City uses but might be worth checking on another receiver and, if you receive second harmonic, getting in touch with Radio City to tell them.
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Old 26th Feb 2020, 4:01 pm   #7
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Default Re: Wrong station on shortwave band 2

The transmitter is in Bebington just a couple of miles from you in Eastham. I think the TX power is 1kw and Ofcom say harmonics must be at least 40db below that, so that I think is 10 watts.
Quite possible that you can hear the second harmonic.
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Old 26th Feb 2020, 4:06 pm   #8
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Default Re: Wrong station on shortwave band 2

It's the 2nd harmonic.

Remember that this may not actually be being radiated from the transmitter, but can be created by something local.

You haven't perhaps got another receiver in the house that's tuned to the fundamental frequency, have you? Mixers depend on non-linearity and it's quite possible that the mixer in another radio could be acting as a doubler and reradiating.
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Old 26th Feb 2020, 4:49 pm   #9
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Default Re: Wrong station on shortwave band 2

HI,Guys
It seems to be dying out now gone very low.
I will leave it until later to see if it improves,there is a lot of
noise now.Never had this before so thanks for your input.

G6Tanuki,Thanks no other radios on.

Nuvistor.
Thank you for that is possible, never give them a thought.

Sorry Russell W. B.G4YLI. missed you had visitors. I will check some other radios and report back later.
thanks again Guy's
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Old 26th Feb 2020, 11:07 pm   #10
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Default Re: Wrong station on shortwave band 2

HI Gu'ys
Did not get chance to test another radio.
I think the fault was the TX end as been said, it has all
gone OK now and all channels received crystal clear.

So I did try to contact BBC but to no avail, as you can't get through.

We had a fault once before of sound going up and down for nearly
a day and I taped it sent Emails still got no reply so I put it on Facebook,
still no reply.

Now they are going over to FM/DAB shortly, I will terminate them.
Thanks again for your input and
This post can be closed now thank you mods.
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Old 26th Feb 2020, 11:31 pm   #11
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Default Re: Wrong station on shortwave band 2

Quote:
Originally Posted by russell_w_b View Post
Used to find this at BBC Washford on the Doherty transmitters if the l/4 carrier-peaker network went off tune slightly, the second harmonic would shoot up and put BBC Radio 1 right in the fishfone emergency channel on 2178kHz. We would soon get a call from the Portishead radio station!
I'm trying hard to remember the context/time, but I do recall hearing that sea-going folk over quite a wide area somewhere were getting quite exercised that some was apparently re-broadcasting Radio 1 on 2182 and that it had been going on for many hours without a break! One suggestion was that R1 was playing in a wheel-house somewhere and an unintentionally-activated transmitter was picking it up. Perhaps after that it was realised that it was a harmonic problem that Portishead were now wise to. It just goes to show what a headache frequency allocation can sometimes turn out to be.
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Old 27th Feb 2020, 12:25 am   #12
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Default Re: Wrong station on shortwave band 2

Quote:
Originally Posted by turretslug View Post
Perhaps after that it was realised that it was a harmonic problem that Portishead were now wise to. It just goes to show what a headache frequency allocation can sometimes turn out to be.
It happened a couple of times when I was attached to Rampisham, thirty-odd years ago. Washford right on the Bristol Channel, of course, radiating Radio 1 on 1089kHz. The faults were attended to and sorted right away. Well, as right away as the journey from Rampisham to Watchet!
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Old 27th Feb 2020, 11:58 am   #13
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Default Re: RCA AR88D. Wrong station on shortwave band 2.

That memory set my mind churning overnight.... and I now think I remember that it was actually an appeal by a Radio 1 DJ (DL-T?) over the air as regards the apparent "nuisance broadcast", appealing to folk to check their 2182 situation as a lot of complaints had been coming in from a particular region. That it went that high suggests that it had been going on for a while, and that it wasn't until the complaint went to the BBC that someone twigged that it was a transmitter harmonic, rather than incompetence or malfeasance on a third party's part. Perhaps a BBC tech spotted the maths, and the answer got back to the maritime authorities, who were then able to quickly contact the appropriate people on subsequent occasions.

The timescale would suggest early/mid '80s- I wonder if there is any record or even recording of this particular piece of Radio 1 output?
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Old 27th Feb 2020, 10:53 pm   #14
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Default Re: RCA AR88D. Wrong station on shortwave band 2.

The third harmonic of the BBC TV 405 line sound carrier from Holme Moss fell in the 2m amateur band at 144.750MHz.

Generally speaking, it was regarded as a useful accurate beacon.
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