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Any idea what the sensitivity of an AK-55 was originally?
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Brenda Ann
Feb 9, 2012, 2:45:38 PM2/9/12
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I've been working on a chassis, and it seems to be quite good now for a TRF.
I've measured it down to ~30uV for a listenable signal (I can get down to
~20uV with a 400 Hz test tone). I can't say whether the impedence is matched
between my sig gen (a nice Agilent) and the antenna input of the radio. This
test was done in the quietest part of the dial (725 KHz) where my noise
floor doesn't seem as ludicrous as it normally is. Just wondering if this is
good for this radio, or whether I should try some more tweaking. I have
aligned the three tuning caps to track quite well across the dial (about
500-1650 KHz).
Thanks for your time.
I've measured it down to ~30uV for a listenable signal (I can get down to
~20uV with a 400 Hz test tone). I can't say whether the impedence is matched
between my sig gen (a nice Agilent) and the antenna input of the radio. This
test was done in the quietest part of the dial (725 KHz) where my noise
floor doesn't seem as ludicrous as it normally is. Just wondering if this is
good for this radio, or whether I should try some more tweaking. I have
aligned the three tuning caps to track quite well across the dial (about
500-1650 KHz).
Thanks for your time.
Alan Douglas
Feb 9, 2012, 9:53:10 PM2/9/12
to
From charts published by Radio Frequency Laboratories in September
1929, at 725kHz the RF input is about 110 microvolts at the antenna
terminals, to obtain 100 mW at the speaker terminals into a resistive
load.
1929, at 725kHz the RF input is about 110 microvolts at the antenna
terminals, to obtain 100 mW at the speaker terminals into a resistive
load.
Brenda Ann
Feb 9, 2012, 10:59:17 PM2/9/12
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"Alan Douglas" wrote in message
news:4e19j7pbf13djjppj...@4ax.com...
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Sounds like I'm right in the ballpark, then. Haven't measured audio output,
but at 100mW at 725 KHz, it's got a good room filling audio with good S/N.
Alex Pogossov
Feb 10, 2012, 5:16:11 AM2/10/12
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"Brenda Ann" <newsg...@fullspectrumradio.org> wrote in message
news:2f2dnR4VvJP5v6nS...@giganews.com...
The rule of the thumb is, when connecting a 2-3m long (or any other
practical length) antenna you are able to hear some static or fluoros
humming, then the sensitivity is sufficient. No need to increase it further,
risking stability, overloading and distortion, etc. Important that you seem
to have achieved good tracking.
Alan Douglas
Feb 10, 2012, 4:25:33 PM2/10/12
to
I forgot to add that the input signal was modulated at 30%.
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