I am restoring a Hallicrafters S-77A boatanchor. It works great, but when receiving a station, there is hum, but with no signal there are just few pops and crackles. I know about this, but for the time being the hard drive between my ears is not finding it. What is the name of this phenominum??? Thanx,
Lewis

Google "modulation hum," and see if that is your problem.
Doug

:I am restoring a Hallicrafters S-77A boatanchor. It works great, but when receiving a station, there is hum, but with no signal there are just few pops and crackles. I know about this, but for the time being the hard drive between my ears is not finding it. What is the name of this phenominum??? Thanx,
:Lewis

:Google "modulation hum," and see if that is your problem.
:Doug

:THAT's the name I've been trying to remember!! THANX

::I am restoring a Hallicrafters S-77A boatanchor. It works great, but when receiving a station, there is hum, but with no signal there are just few pops and crackles. I know about this, but for the time being the hard drive between my ears is not finding it. What is the name of this phenominum??? Thanx,
::Lewis

I have hum only on strong, local stations, whenever the AVC has to work hard. Does the hum go away in MVC or if you turn down the RF gain?

: I have hum only on strong, local stations, whenever the AVC has to work hard. Does the hum go away in MVC or if you turn down the RF gain?

Absolutely yes!
Lewis

:: I have hum only on strong, local stations, whenever the AVC has to work hard. Does the hum go away in MVC or if you turn down the RF gain?
:
:Absolutely yes!
:Lewis

Hokay!!
I applied a "technical tap" to the radio, and the hum problem went away. used a bamboo skewer (100 for $.99 at Publix, wonderful for getting into places where you don't to put your fingers) and found a contact on the banc switch that I could make the trouble come and go. A bit of contact cleaner and some exersizing the switch, and the radio is now working perfectly, except it only seems to speak Spanish.
Lewis

Lewis, I would have expected that after using the bamboo skewer to hear mainly Chinese ;>)
Doug

:used a bamboo skewer (100 for $.99 at Publix, wonderful for getting into places where you don't to put your fingers) and found a contact on the banc switch that I could make the trouble come and go. the radio is now working perfectly, except it only seems to speak Spanish.
:Lewis

:Lewis, I would have expected that after using the bamboo skewer to hear mainly Chinese ;>)
:Doug
:
::used a bamboo skewer (100 for $.99 at Publix, wonderful for getting into places where you don't to put your fingers) and found a contact on the banc switch that I could make the trouble come and go. the radio is now working perfectly, except it only seems to speak Spanish.
::Lewis

Seriousljy, I did get a religeous English speaking broadcast from China.
Lewis

::Lewis, I would have expected that after using the bamboo skewer to hear mainly Chinese ;>)
::Doug
::
:::used a bamboo skewer (100 for $.99 at Publix, wonderful for getting into places where you don't to put your fingers) and found a contact on the banc switch that I could make the trouble come and go. the radio is now working perfectly, except it only seems to speak Spanish.
:::Lewis
:
:
:Seriousljy, I did get a religeous English speaking broadcast from China.
:Lewis
:

Hello........it is I again..I cleaned the chassis, got about two pounds of dirt off of it, and now I have a dead radio...water in the IF xfmrs perhaps??
I put it in a warm oven for a while, and it gets one station with tons of hum modulation now. I'll put it out on my deck for the day, there is a compelete blue sky with a mild breeze that should dry it out..otherwise, I may have a radio to fix.
Lewis