Looking for Sensitive BCB Superhet Tuner
 

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

In article , WShoots1 wrote:
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.

Yes, but they weren't exactly good. Okay, they weren't any good. I built
a really neat 10M converter using a compactron from a QST project and found
the selectivity issue was pretty serious even though most folks were running
AM and the bands weren't as crowded.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Yes, but they weren't exactly good. Okay, they weren't any good.

G I'd never owned any of them, which ranged from 75M to 10M. Gonset made a
tri-bander, too, for, I believe, 75, 20, and 10.

I had a separate transmitter and receiver for 100W 75M mobile (with three
dynamotors in the trunk!). Then I bought a Gonset Communicator II for 2M. I had
great fun with that.

73,
Bill, K5BY

In article ,
"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?





GE Superset

The Gonset converter worked fine: it was the car radio which was
wholly unsuited for the task. But they are fine for BCB DXing if the
IF is narrowed down, or as is, given a good antenna, for audiophile
AM.

Best is an aircraft ADF set. New ones are several thousand dollars
but old tube and non-TSOd early SS types may be had cheaply. I got a
huge pile of tube and early solid state avionics-dynamotors, tuner
assemblies, and all-from a FBO who was grateful I'd haul it off.