Thank you Stefan: I have been toying with Bridge-T diplexers to better
match my LPF or BPF filters to the preamps on two different LF/MF
converters,
and I believe I see a worthwhile improvement in matching the filter output
to the preamp input. It is a challenge to build a filter to 1% tolerance
and impedance match
with silver mica caps and FT50-61 inductors, even with Litz wire like 17/40
size. So having a good Z match reference between the filter and preamp
stages seems to help improve performance.
Perhaps using a Bridge-T diplexer at LF/MF/HF can be loosely compared to
using an isolator at microwave frequencies, to improve return loss and
preamplifier stability.
Except the bridge-T diplexer is bi-directional and EM operational. whereas
an isolator at microwave range is a directional matching device which is a
magnetic dominant component...
In either case, they are usually (much) more efficient than using
attenuator pads for inter-stage Z matching....
This may be old information to others, but it made for a worthwhile LF
experiment over the past season for me..
73, Mike wa3tts.
----- Original Message -----
From: "DK7FC" <[email protected]>
To: <[email protected]>
Sent: Saturday, March 24, 2018 1:13 PM
Subject: Re: LF: Re: [Lowfer] Tx this w/e 136.172kHz
Congrats to Mike and all involved.
Do the good old times come back?!
73, Stefan
Am 24.03.2018 16:03, schrieb N1BUG:
I had almost a full call sign capture in the 2300 hour.
http://www.n1bug.com/g3xdv-1.jpg
Bits and pieces at 0100 and 0300. I fell asleep and didn't disable
my transmitter for the 0500 hour but I could see enough in my pauses
to know the first 40 minutes would have been clean copy with a big
fade after that.
73,
Paul N1BUG
On 03/24/2018 10:45 AM, Michael Sapp wrote:
Mike& All:
Noticed this at QRSS30 in the 0300 hour
https://www.dropbox.com/s/ubyhg6sbdimaoj4/xdv1.jpg?dl=0
Switched to QRSS60
https://www.dropbox.com/s/ik5xudqunr2gcz1/xdv2.jpg?dl=0
Almost a call sign capture. I can divine an "X" for the first character
if
I count the startup smudge on the waterfall display at 137.172. The "D"
is
missing
the second "dit". The V is visually detectable ending at the top of the
hour even though the dash is fading...
Received on my NE EWE antenna with 300 kHz LPF and 137 kHz bridge T
diplexers on I/O of 2N3904 broadband preamp, then to mixer, etc..
https://www.dropbox.com/s/p99k2xfl4q2ui3i/IMG_1125.JPG?dl=0
Thanks (very very much) for the beaconing....
73 Mike wa3tts EN90xn
----- Original Message -----
From: "Mike Dennison"<[email protected]>
To:<[email protected]>;<[email protected]>
Sent: Friday, March 23, 2018 1:40 PM
Subject: LF: Tx this w/e 136.172kHz
I will be transmitting QRSS60 on 136.1721kHz overnight tonight and
for the next two nights. Transmissions will comprise my callsign, and
will start exactly on the odd-numbered (UTC) hour from 1900 to 0500
and last just over an hour (eg 1900-2002, 2100-2202 . . . to
0500-0602).
Reports will be welcome as always.
Mike, G3XDV
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