FM hiss, vintage 1973 receiver

[mc]

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

 

[Erich J. Schultheis, The Man with the 15 inch Cock]

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

Nothing wrong with it, other than it should have been thrown out 20
years ago. Why are you still dicking with old recievers. Don't you have
a girlfriend or a life?

 

[JANA]

It is impossible to guess at what can be wrong. There are many components
involved to receive, and process the signal. An experienced tech who is
knowledgeable in servicing tuners should be able to troubleshoot the tuner
for you, and find the failed components.

--

JANA
_____


FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

 

[Joe Kesselman]

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

If the receiver has a multipath filter, try that.

 

[Guest]

Nothing wrong with it, other than it should have been thrown out 20
years ago. Why are you still dicking with old recievers. Don't you have
a girlfriend or a life?

Aaaah, shaddap before we bomb Dresden. Again.


Hugs & kisses,
Francois.

 

[mc]

It is impossible to guess at what can be wrong. There are many components
involved to receive, and process the signal. An experienced tech who is
knowledgeable in servicing tuners should be able to troubleshoot the tuner
for you, and find the failed components.

I knew that already, except the "impossible" part.

 

[gb]

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level.
It disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

How good is your antenna for the station that you are trying to receive?
Do you have an outside antenna?

These symptoms are common for fringe reception (stereo not full quieting -
but mono is better).

If you are trying to receive the signal with a small dipole in a tall steel
and concrete high rise - then you are not getting sufficient signal strength
to the receiver.

gb

 

[Dave Plowman (News)]

If the receiver has a multipath filter, try that.

That would be useful. ;-) Do you mean multiplex?

 

[Peter Larsen]

mc posted a question compliant with usenet standard: 3416554677697809809
section B, page 27, paragraph 8: Any initial question must omit at least
one piece of vital information, otherwise it can not be considered for
followups.

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

This is not about age - rather about quality, unless of course something
is broken and age, if it was left unused for an extended period of time,
may have caused some components to deteriorate. Have you just found or
gotten it or do you know for sure that it has deteriorated. Try adding
the elementary information: make and model, someone may then know
whether it was likely to have been good or bad ex works.


Kind regards

Peter Larsen

 

[Smitty Two]

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

Is it only on FM, or with other sources, too? If it's noisy from a line
input too, a dirty stereo/mono switch could be at fault. Some of those
old pushbutton types were pretty marginal.

 

[mc]

How good is your antenna for the station that you are trying to receive?

Do you have an outside antenna?

A 1/4 wave ground plane in the attic of a wood-framed house. Some of the
local stations (within 5 miles) are very strong, and I can get some stations
80 miles away (not with good audio). The antenna is not the problem. What
concerns me is that even the very strongest signals do not give full
quieting on stereo.

 

[mc]

FM stereo receiver, vintage 1973, has a noticeable background hoise

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

That I knew...

This is not about age - rather about quality, unless of course something
is broken and age, if it was left unused for an extended period of time,
may have caused some components to deteriorate. Have you just found or
gotten it or do you know for sure that it has deteriorated. Try adding
the elementary information: make and model, someone may then know
whether it was likely to have been good or bad ex works.

Nikko STA-5010. FM stereo demodulator is a UPC554C chip.

Circuit diagrams somewhere on www.covingtoninnovations.com/audio.

Thanks!

 

[mc]

Is it only on FM, or with other sources, too? If it's noisy from a line
input too, a dirty stereo/mono switch could be at fault. Some of those
old pushbutton types were pretty marginal.

Only on FM stereo. No problems with any other signal source, stereo or
mono. Anyhow, would a dirty switch produce continuous hiss?

 

[Asimov]

"mc" bravely wrote to "All" (03 Jan 06 00:00:37)
--- on the heady topic of "FM hiss, vintage 1973 receiver"

mc> From: "mc" <[email protected]>
mc> Xref: core-easynews rec.audio.tech:186013
mc> sci.electronics.repair:353686

mc> FM stereo receiver, vintage 1973, has a noticeable background hoise
mc> (hiss/white noise) on FM stereo regardless of the incoming signal
mc> level. It disappears completely upon switching to mono.

mc> Is this normal in a receiver of that age? If not, what components are
mc> likely to be deteriorating?


Vintage 70's equipment is making a comeback and is all the rage now.
A big noise is absolutely normal between stations if there is no
muting circuit but when tuned to a station the noise should drop
dramatically. It is also normal to have a little extra hiss in stereo.
However I have no idea how much hiss is normal for your particular
receiver. If it seems excessive then perhaps the components to look at
are electrolytic capacitors around the stereo decoder/demultiplexer
circuitry. If you can find a separation adjustment trimmer, sometimes
reducing the separation a little can lessen the hiss significantly
without affecting the stereo effect too much.

A*s*i*m*o*v

.... A stereo system is the altar to the god of music.

 

[Asimov]

"null" bravely wrote to "All" (03 Jan 06 05:56:45)
--- on the heady topic of "Re: FM hiss, vintage 1973 receiver"

nu> From: [email protected] ((null))
nu> Xref: core-easynews rec.audio.tech:186020
nu> sci.electronics.repair:353710


nu> In article <[email protected]>,
nu> Erich J. Schultheis, The Man with the 15 inch Cock.


nu> Aaaah, shaddap before we bomb Dresden. Again.

Don't feed the trolls!

A*s*i*m*o*v

.... Your E-Mail has been returned due to insufficient voltage.

 

[David Tweed]

A 1/4 wave ground plane in the attic of a wood-framed house. Some of the
local stations (within 5 miles) are very strong, and I can get some stations
80 miles away (not with good audio). The antenna is not the problem.

Don't be so sure. It used to be (and probably still is) that commercial
FM transmitters were almost always horizontally polarized. A pair of
crossed folded dipoles (made from 300 ohm twinlead) in your attic will
probably have markedly superior performance to your vertical quarter-wave.

-- Dave Tweed

 

[mc]

Asimov wrote:
Vintage 70's equipment is making a comeback and is all the rage now.
A big noise is absolutely normal between stations if there is no
muting circuit but when tuned to a station the noise should drop
dramatically. It is also normal to have a little extra hiss in stereo.
However I have no idea how much hiss is normal for your particular
receiver. If it seems excessive then perhaps the components to look at
are electrolytic capacitors around the stereo decoder/demultiplexer
circuitry. If you can find a separation adjustment trimmer, sometimes
reducing the separation a little can lessen the hiss significantly
without affecting the stereo effect too much.


Thanks. Several people are saying that. I'll also look at the power supply
for the tuner section (which has its own regulator). The power may be noisy
or not the correct voltage.

 

[mc]

Don't be so sure. It used to be (and probably still is) that commercial
FM transmitters were almost always horizontally polarized. A pair of
crossed folded dipoles (made from 300 ohm twinlead) in your attic will
probably have markedly superior performance to your vertical quarter-wave.

Thanks, I'll try that.

I thought they were going to vertical polarization because of car radios.
I'm wondering where I read that, and whether it's true.

 

[David Tweed]

I thought they were going to vertical polarization because of car
radios. I'm wondering where I read that, and whether it's true.

I'm pretty sure that commercial VHF services like FM radio and TV
prefer horizontal polarization because of fewer problems with
absorption and/or diffraction from vertical objects such as trees
and poles.

Also, most customers for these services have fixed antennas, and
can do horizontal just as easily as vertical. FM radio in the car
is an exception, as you note, but most cars these days either have
a horizontal dipole in the window glass somewhere, or a whip that
has a significant amount of tilt.

On the other hand, VHF services that are intended *primarily*
for mobile customers (public service bands, etc.) use vertical
polarization because the car antennas really want to be vertical
whips for mechanical simplicity.

-- Dave Tweed

 

[Karl Uppiano]

I'm pretty sure that commercial VHF services like FM radio and TV
prefer horizontal polarization because of fewer problems with
absorption and/or diffraction from vertical objects such as trees
and poles.

Also, most customers for these services have fixed antennas, and
can do horizontal just as easily as vertical. FM radio in the car
is an exception, as you note, but most cars these days either have
a horizontal dipole in the window glass somewhere, or a whip that
has a significant amount of tilt.

On the other hand, VHF services that are intended *primarily*
for mobile customers (public service bands, etc.) use vertical
polarization because the car antennas really want to be vertical
whips for mechanical simplicity.

-- Dave Tweed

Almost all commercial FM stations in the US are circularly polarized (1/2
power vertical; 1/2 power horizontal, 90 degrees out of phase). That covers
both types of antennas, and if you have a CP receiving antenna, you can
dramatically reduce multipath if it is oriented toward the transmitter.