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 |
开云体育Not 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 |
开云体育Hi 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