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A little help with HF reception

PostPosted: Sat Sep 30, 2017 11:33 am
by welshmonitor
Hi guys & girls

I have a NASA HF-4E receiver, not the best in the world I know, but bought it to get back into HF listening, the problem I have is that I cant hear a damn thing from it :dizzy:

I have a 10 meter longwire antenna that runs approx 20ft above ground to some trees (unable to get it any higher than that at the present) that feeds into a 9:1 UnUn then Coax run of about 25ft (cant make it any shorter due to position of my property) and I cant even hear Volmet's :huh:

I have had HF receivers using the exact same UnUn & coax at my previous property and it worked ok, so I'm at a loss as to what could be wrong. Ideally I would like to take the receiver to a local amateur operator or another SWL that could test it for me, but I'm afraid that I dont know anybody that would do this. The coax is in very good condition, so I dont think that is the problem either.

Does anybody have any ideas what could be wrong?? I understand it's a long shot because it could be any one of the components (receiver, UnUn, coax) at fault, but I'm hoping for some ideas if possible.

Many thanks in advance for any advice etc :thumbup:

Re: A little help with HF reception

PostPosted: Sat Sep 30, 2017 11:57 am
by Alfie
Have you tried the hf am broadcast band first to test your receiver and antenna ? people listen to them on sw receivers with small antennas so you should be able to pick them up alright. if not you know there is something wrong

Re: A little help with HF reception

PostPosted: Sat Sep 30, 2017 1:17 pm
by welshmonitor
Hi Alfie,

Thanks for the advice, I have had a quick tune around the AM broadcast bands and i am receiving them quite loud & clear, also I just tuned to the UK Shannon Volmet on 5.5050 & the RAF Volmet on 5.450 and to my surprise I can hear the transmission but with a minimum of S7-S8 of heavy noise interference. Normally the interference/noise overwhelms the transmission and I struggle to hear anything.

So I'm guessing it not the receiver, but possibly a prob with either the UnUn or the placement of the longwire ??



Re: A little help with HF reception

PostPosted: Sat Sep 30, 2017 1:41 pm
by m0lsx
What level ofg electrical noise are you getting?If it's anything like me, you will get very little to hear at home.
Also over what period have you been trying? As we have been hit by some strong solar winds lately which have knocked signals off HF.
Have you checked the attenuator is set correctly? And I say that one from personal experience & also how is the RF gain, band width & antenna switch set?
Have you checked the coax for continuity & have you tried with the un/un out of line?
There are a lot of checks to make before you assume anything.

Re: A little help with HF reception

PostPosted: Sun Oct 01, 2017 10:01 am
by welshmonitor
I have been listening on and off over the past 2 months & the Rx has been terrible, as previously stated I'm struggling to hear the UK Volmet's.

The attenuator has just 2 settings on this receiver (on/off) and it is set to off, The antenna switch is set to normal NOT to active, No RF gain on this receiver, just a volume and clarify knob.

As for the UnUn & coax continuity I have been unable to test those at the moment, but will do as soon as I have the chance.

Thanks for the advice/info m0lsx it's very much appreciated :thumbup: