[1000mp] Apparent receiver overload on 80M

[Pete Smith]

At 03:43 PM 11/29/2004, you wrote:

>Only on 80M, my S-meter runs S5-S7 all the time just on band noise. The NB 
>has no effect, and it doesn't sound like power line noise. If I press the 
>IPO switch, the S-meter goes to zero unless there is a signal present. 
>During the day, switching in 6dB of attenuation has the same effect. At 
>night, 6dB isn't always enough. These symptoms indicate to me that 
>something is overloading the receiver, but there is nothing obvious to 
>cause this. Any ideas as to what it could be, or is this normal for the 
>receiver on 80M with an inverted Vee?

Seems to me I recall reading that the MP/Mk 5 S-meter is only a couple of 
dB per S unit below S9, so maybe what you're seeing is 10 dB of noise above 
S0.  That's consistent with my experience; tune in a desired signal at S8, 
switch in the first step of attenuator, and watch it drop to S5.

Right now, at about an hour before sundown, mine is reading S3-4, with 
frequent S5 and occasional S7 bursts when my array is pointed south, and S1 
with occasional bursts to S7 when pointed north.  My hunch is that a lot of 
what I'm hearing to the south is incident to a 500 kv line about 2 miles away.

My daytime 160-meter noise level on my transmit vertical is a constant 
S8.  Gotta get my receive antennas out now that the field has been mowed!

73, Pete N4ZR