Ok Paul,
Its round the Q and Q + not Q , configuration , the latest drivers
allow that to be selected , the single feed seems to work fine ,
but still needs some filtering to prevent images ..
I think, possibly a pass band limited pre-amp would help for MF/LF
, the gain drop's past a couple of MHz and the 200 ohms z needs some
matching , may be the mini-whip is providing this aspect ?
There are image responses linked to the sample rate , a pre-selector as
opposed to a 'tuner' would be 'ok' for HF , I think .
I have another 'now' low band dongle . used to be high band , but
after a 7 MHz session , with it connected to a 10 mtr Ae , the vhf
front failed .. so that's a candidate for mf/lf conversion , these
have two life's !
One of Jim's two active device band limited pre-amps , with 200 ohms
o/p z would be ideal , or use the toroid as the o/p coupling device ?
that may be the most elegant configuration ?
73-G,
--------------------------------------------------
From: <[email protected]>
Sent: Wednesday, June 18, 2014 12:23 PM
To: <[email protected]>
Subject: Re: LF: MF CW now!
Hello Graham, LF
To be honest I have not tried other feeding methods for the AD than a
trifilar 1:4 transformer. I used a beefier toroid (FT50-43) and more
turns to get a XL of 200 ohms at 400 kHz for the 50 ohm winding. The
concept of having the AD and antenna line galvanically separated and the
antenna input DC-shorted appealed to me since there is no other
protection against static.
I will give capacitor-coupling a try at some point.
A simple LPF is mandatory at least if one plans to use wire antennas,
otherwise there is a large risk of interference from VHF FM broadcasting.
BR
Paul-Henrik, OH1LSQ
Quoting Graham <[email protected]>:
Paul,
Q , do you find the transformer feed better than , simply
connecting via a capacitor to the AD ?
73-G,
--------------------------------------------------
From: <[email protected]>
Sent: Tuesday, June 17, 2014 11:38 PM
To: <[email protected]>
Subject: Re: LF: MF CW now!
Hello Stefan, LF
Your CQ's are 539 here on a Mini-Whip directly into the
demodulator" -chip on a slightly hardware-hacked RTL-SDR TV USB-dongle
:-).
The "hack" is just bypassing the VHF/UHF tuner-chip and running
straight into the +I and -I inputs of the RTL2832U via a 1:4 XFRMR.
No TX here at the moment but receiving you so well on a hacked 10 euro
USB-dongle and the old MiniWhip is just a tad more than I expected...
BR
Paul-Henrik, OH1LSQ
Vaasa, KP03SD
Quoting DK7FC <[email protected]>:
472.2 kHz...
Anyone for a QSO?
73, Stefan
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