Am looking for a reasonable cost BCB superhet tuner or receiver (valve or
solid state) which has a known sensitivity of 0.1 microvolts or less for 10
dB s+n/n ratio. May be a manufactured or kitset radio. All advice and
references appreciated. TIA.
Graeme

In article , "Graeme" wrote:

Am looking for a reasonable cost BCB superhet tuner or receiver (valve or
solid state) which has a known sensitivity of 0.1 microvolts or less for 10
dB s+n/n ratio. May be a manufactured or kitset radio. All advice and
references appreciated. TIA.
Graeme

Is this even possible with an antenna connected considering atmospheric
noise, or is atmospheric noise very low in the Southern Hemisphere and
Australia?


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

"John Byrns" wrote in message
...
In article , "Graeme"
wrote:

Am looking for a reasonable cost BCB superhet tuner or receiver (valve
or
solid state) which has a known sensitivity of 0.1 microvolts or less for
10
dB s+n/n ratio. May be a manufactured or kitset radio. All advice and
references appreciated. TIA.
Graeme

Is this even possible with an antenna connected considering atmospheric
noise, or is atmospheric noise very low in the Southern Hemisphere and
Australia?


Regards,

John Byrns


The sensitivity figure was intended to be 1.0 microvolt.

I've corrected the message and included it again below.

Thanks for catching it John.

Graeme

Corrected message:

Am looking for a reasonable cost BCB (MW) superhet tuner or receiver (valve
or solid state) which has a known sensitivity of 1.0 microvolt or less for
10 dB s+n/n ratio. May be a manufactured or kitset radio, or a magazine
project. All advice and references appreciated. TIA.
Graeme

"Graeme" wrote in message
...

Am looking for a reasonable cost BCB (MW) superhet tuner or receiver
(valve
or solid state) which has a known sensitivity of 1.0 microvolt or less for
10 dB s+n/n ratio.

1 uV at what impedance? what bandwidth?

R J Carpenter wrote:
"Graeme" wrote in message
...

Am looking for a reasonable cost BCB (MW) superhet tuner or receiver
(valve
or solid state) which has a known sensitivity of 1.0 microvolt or less for
10 dB s+n/n ratio.

1 uV at what impedance? what bandwidth?

Collins R-390A can do that with the unbalanced input with a CW signal,
and exceed it handily.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

The ICOM R-71A is excellent but pricey. However I've found success with
automobile radios. You can buy or build a 12 volt 1.5 amp power supply
inexpensively.

"Graeme" wrote in message
...
Am looking for a reasonable cost BCB superhet tuner or receiver (valve or
solid state) which has a known sensitivity of 0.1 microvolts or less for
10
dB s+n/n ratio. May be a manufactured or kitset radio. All advice and
references appreciated. TIA.
Graeme

"R J Carpenter" wrote in message
...

"Graeme" wrote in message
...

Am looking for a reasonable cost BCB (MW) superhet tuner or receiver
(valve
or solid state) which has a known sensitivity of 1.0 microvolt or less
for
10 dB s+n/n ratio.

1 uV at what impedance? what bandwidth?

Assume 50 ohms input impedance, and 6 KHz receiver bandwidth (3 KHz received
audio).

Graeme

"Graeme" wrote in message
...
"R J Carpenter" wrote in message
...

"Graeme" wrote in message
...

Am looking for a reasonable cost BCB (MW) superhet tuner or receiver
(valve
or solid state) which has a known sensitivity of 1.0 microvolt or less
for
10 dB s+n/n ratio.

1 uV at what impedance? what bandwidth?

Assume 50 ohms input impedance, and 6 KHz receiver bandwidth (3 KHz
received
audio).

BlueCat suggested a car radio.

Car radios have had bandwidths not far different from 6 kHz for some years
now.

Let's guess that the input impedance of an automobile AM radio is 5000 ohms.
That means that 10 uV at 5000 ohms is the same signal power as your 1 uV at
50 ohms. I'd guess that a good car radio would do that ... you might have
to raid a junk yard to find a radio old enough to be "good". Especially
avoid the recent cars with an amplified AM antenna on the roof.

Bob

In article , Blue Cat wrote:
The ICOM R-71A is excellent but pricey. However I've found success with
automobile radios. You can buy or build a 12 volt 1.5 amp power supply
inexpensively.

Old 1970s car radios are in general extremely sensitive. Selectivity is
sort of doubtful on a lot of them, but because they are normally used with
a small whip antenna, high sensitivity is essential. A Delco AM radio
should be available for free at your local junkyard.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Selectivity is sort of doubtful on a lot of them,

Back in the 1950s, even 1960s, car radios were used as tunable I.Fs for HF ham
band convertors for mobile reception, like those made by Gonset.

Bill, K5BY