S9 noise on HF with or without antenna
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Dear Group, I have a bit of a strange question. My FT847 has nothing but S9 of noise on HF (I work mostly satellite these days so only just noticed it). I tried all bands but seem to be blighted with an S9 signal with or without the antenna connected. The other issue is when I tune to a strong AM station in the lower broadcast band 2.2mhz seemed to be the strongest +50db on AM but the audio is dreadful and sounds splattered, clipped and inaudiable. I have been using a passive loop on HF and I¡¯m fearing DC or a strong signal has landed in the front end and done damage.?
Before I tear my radio apart to resolve this I wondered if anyone had pointers. I know the FT897 used to suffer with S9 all the time due to the 455khz ceramic filters going bad but don¡¯t think the FT847 uses them. ? Any help would be really appreciated. thanks in advanced, de Spence M0STO? see below the test gear on hand to resolve this. test gear: Marconi 2955 radio test set Marconi 2022 Signal Generator Rigol DSA1030A spectrum analyser Phillips 3833 60mhz Scope AF generator? VVM logic probe etc. GDO |
¿ªÔÆÌåÓýNot sure of the FT847, but does it have a function or ability to turn off the AGC ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Spence M0STO via groups.io ? Dear Group, I have a bit of a strange question. My FT847 has nothing but S9 of noise on HF (I work mostly satellite these days so only just noticed it). I tried all bands but seem to be blighted with an S9 signal with or without the antenna connected. The other issue is when I tune to a strong AM station in the lower broadcast band 2.2mhz seemed to be the strongest +50db on AM but the audio is dreadful and sounds splattered, clipped and inaudiable. I have been using a passive loop on HF and I¡¯m fearing DC or a strong signal has landed in the front end and done damage.? -- Bill, K2WH |
¿ªÔÆÌåÓýHi Bill and thanks for the reply. I had a little nose inside and injected a smallish signal and found that there was stray RF on the IF from the G4HUP PAT board I fitted many years ago.?? I feel a bit silly now as the PAT board has worked flawlessly but for some reason I was getting some IMD and broadcast FM from the 3m band. I really love my FT847 and I have a spare (A2 US Import and C2 UK specifications) and I really don¡¯t want to see them damaged. So I¡¯ve taken out both PAT board (IF tap and 2nd receiver) and they are now in the trash. The main problem is the IF was being overloaded even though I was using the 2nd receiver PAT board and not the IF tap for Panadapter. ? Thanks for the heads up but this is resolved and I doubt I will be re-visiting the PAN adapter anytime soon. De Spence M0STO? Sent while portable! please excuse typos. On 5 Jan 2022, at 12:29, Bill <k2wh@...> wrote:
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Spence G5STO
Bill