From: Herbert Schulz 
Subject: Re: [drakelist] R8B Low Sensitivity?????


Herbert Schulz  made an
utterence to the drakelist gang
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100 feet for a long-wire is not long compared to the wavelength
at 60[kHz], which is appr. 5000[m] or appr. 16000 feet. So,
the length of the antenna is appr. 1/160th of the wavelength -
an indication, that it will not develop much voltage at this
frequency. Maybe testing a magnetic antenna - like a loop with
some windings and a diameter of 1...2[m] maybe a suggestion?

The second suggestion will be, to measure the receivers sen-
sivity. At this frequency, an reasonable function generator
capable of a low-distortion sine output, followed by a home-
brewn, shielded, multistage resistive attenuator (in the range
of 80...100[dB], depending on the generators capability of
output level variation), should do the job as a substitute
for a calibrated signal generator. Amplitude caibration of the
generator at it's output terminals should not be a problem
with any common and cheap "20[MHz] style" analog oscilloscope
with a accuracy that is sufficient for ham needs.

vy73 de Herbert, DG7MCC


Jim schrieb:

> Jim  made an utterence to the drakelist gang
> ----------------------------------------------------------------------
> I am using a late serial number Drake R8B that the display shows it
will tune down
> to 10kHz.  Also the serial number is high enough that Drake says the radio will
> tune and receive below 100kHz.
>
> The issue is my R8B seems deaf below 100 kHz.  I connect a long wire (100 feet)
> to the Hi-Z input and cannot even hear a whisper of WWVB at 60kHz.  I have also
> tried a 40 meter dipole on the Lo-Z input and an active whip on the
Lo-Z input with
> the same results.  I can put the radio in the LSB mode and there is zero hint of
> a carrier on 60kHz.
>
> Do other Drake R8B owners have the same experience?
>
> I sent a mail to Drake and they came back saying the radio sensitivity
is not spec'ed
> below 100kHz.  That info is of little help.  The did say I could send the radio
> into them for $25 per hour to have it checked out, but if the radio is poor (by
> design) below 100 kHz, why waste the money.
>
> Also, someone told me that they had a similar problem and it was a
defective I.C.
>
> So...........are there other Drake R8B owners that have a radio that
can "hear"
> below 100 kHz (WWVB for example)??
>
> I am located in the San Diego, Ca area.
>
> Thanks again.
>
> Jim
>
> ----------------------------------------------------------------------
> On Behalf of Jim 
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100 feet for a long-wire is not long compared to the wavelength
at 60[kHz], which is appr. 5000[m] or appr. 16000 feet.
So,
the length of the antenna is appr. 1/160th of the
wavelength -
an indication, that it will not develop much voltage at
this
frequency. Maybe testing a magnetic antenna - like a
loop with
some windings and a diameter of 1...2[m] maybe a
suggestion?
The second suggestion will be, to measure the receivers
sen-
sivity. At this frequency, an reasonable function
generator

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