If you were to temporarily short the antenna the noise should disappear (almost completely)
80 meters is pretty noisy most places and could be made much worse of you are in an urban area with cheap power supplies, lights etc. I see that you are in India and depending on location you may have a great deal of offending electrical devices around.?
The noise from the receiver would be on all bands if it is the ceramic filters. The test is might be to compare on different bands and perhaps listen to a friends radio, perhaps if they could set up at your QTH.
I am lucky in that I have a good service monitor (IFR FM/AM 1200S) to check the signal to noise specs of a radio and be certain.
Often people are quick to blame those ceramic filters for almost any problem on the FT-857 and they COULD be but not even the majority of the time. A quick comparison of your radio with another either at your QTH or another might clear up the issue.

Unless that noise is still there with the antenna disconnected, I'd look for some local source such as a computer, wall-wart power supply or appliance.? Run your radio off 12vdc and start turning off circuit breakers until the noise disappears.?

Ron Jakubowski

K2RJ?

Tab? S5e

If the radio is still noisy without the antenna connected the ceramic filters are cheap and not too difficult to replace, but you have to remove the main board to get at the bottom to unsolder them.
The filters are less than $1.00.
Many people jump to these being the problem for almost any radio issue, but if the radio is internally noisy they are a good bet.?
Other issues like not transmitting on SSB would not be.
If you decide the change them the biggest problem is getting enough heat on the ground plane to unsolder that connection.
I can't speak for noise on 80 meters here as out noise level is so high that the band is unusable for me.?

Check the noise level without the antenna. Sometimes the ceramic filters get noisy.?

Silly question, did tou have an antenna connected to the radio? Probably not, but thought I'd ask anyways.

Regards,

Tony

VA7TF? VE7ACF

On Mon., Jun. 27, 2022, 02:44 Theo Marinos, <marinos.theo@...> wrote:

Hi guys

?

I have discovered that my 857D has developed some internal noise.

?

The radio was removed from the car about 18 months ago as I got a company vehicle, so I took the radio out of my personal car and left it sitting, unpowered on the desk in my shack as the car now sits in the garage. Since then, the only use it gets is on a monthly basis as a receiver only, for monitoring signals during our club’s monthly fox hunt when I will put in on the passenger seat of the work car and connect it to a mag-base antenna listening to the fox as I drive around. At the end of the night, I take it back inside.

?

When previously set up like this during our May fox hunt all was well however last Friday night, when set up in the same manner, I discovered noise in the receiver. At first, I thought it was local but it didn’t go away. Then I thought that perhaps something in the car has gone noisy but when I connected it to a battery at home tonight, I discovered the noise is coming from within the radio. It’s like something inside is self-oscillating. See I recorded tonight with no antenna connected.

?

Any thoughts on what could be causing the issue?

?

Thanks in advance

?

Theo

VK5IR

--

+++++++++++++++

Tony
VA7TF? VE7ACF

Hi guys

?

I have discovered that my 857D has developed some internal noise.

?

The radio was removed from the car about 18 months ago as I got a company vehicle, so I took the radio out of my personal car and left it sitting, unpowered on the desk in my shack as the car now sits in the garage. Since then, the only use it gets is on a monthly basis as a receiver only, for monitoring signals during our club’s monthly fox hunt when I will put in on the passenger seat of the work car and connect it to a mag-base antenna listening to the fox as I drive around. At the end of the night, I take it back inside.

?

When previously set up like this during our May fox hunt all was well however last Friday night, when set up in the same manner, I discovered noise in the receiver. At first, I thought it was local but it didn’t go away. Then I thought that perhaps something in the car has gone noisy but when I connected it to a battery at home tonight, I discovered the noise is coming from within the radio. It’s like something inside is self-oscillating. See I recorded tonight with no antenna connected.

?

Any thoughts on what could be causing the issue?

?

Thanks in advance

?

Theo

VK5IR

In my uneducated opinion, I doubt it's the filters. I had those replaced about 6 years ago, with DC blocking caps fitted at the same time.?

Regards

Theo

On Mon, 27 June 2022, 7:18 pm CT2GLA, <ct2gla@...> wrote:

It may be the ceramic filters "cracks noise" because of moisture inside of them.

73's

A segunda, 27/06/2022, 10:44, Theo Marinos <marinos.theo@...> escreveu:

Hi guys

?

I have discovered that my 857D has developed some internal noise.

?

The radio was removed from the car about 18 months ago as I got a company vehicle, so I took the radio out of my personal car and left it sitting, unpowered on the desk in my shack as the car now sits in the garage. Since then, the only use it gets is on a monthly basis as a receiver only, for monitoring signals during our club’s monthly fox hunt when I will put in on the passenger seat of the work car and connect it to a mag-base antenna listening to the fox as I drive around. At the end of the night, I take it back inside.

?

When previously set up like this during our May fox hunt all was well however last Friday night, when set up in the same manner, I discovered noise in the receiver. At first, I thought it was local but it didn’t go away. Then I thought that perhaps something in the car has gone noisy but when I connected it to a battery at home tonight, I discovered the noise is coming from within the radio. It’s like something inside is self-oscillating. See I recorded tonight with no antenna connected.

?

Any thoughts on what could be causing the issue?

?

Thanks in advance

?

Theo

VK5IR

It may be the ceramic filters "cracks noise" because of moisture inside of them.

73's

A segunda, 27/06/2022, 10:44, Theo Marinos <marinos.theo@...> escreveu:

Hi guys

?

I have discovered that my 857D has developed some internal noise.

?

The radio was removed from the car about 18 months ago as I got a company vehicle, so I took the radio out of my personal car and left it sitting, unpowered on the desk in my shack as the car now sits in the garage. Since then, the only use it gets is on a monthly basis as a receiver only, for monitoring signals during our club’s monthly fox hunt when I will put in on the passenger seat of the work car and connect it to a mag-base antenna listening to the fox as I drive around. At the end of the night, I take it back inside.

?

When previously set up like this during our May fox hunt all was well however last Friday night, when set up in the same manner, I discovered noise in the receiver. At first, I thought it was local but it didn’t go away. Then I thought that perhaps something in the car has gone noisy but when I connected it to a battery at home tonight, I discovered the noise is coming from within the radio. It’s like something inside is self-oscillating. See I recorded tonight with no antenna connected.

?

Any thoughts on what could be causing the issue?

?

Thanks in advance

?

Theo

VK5IR