Message-ID: <D22F7275F2CC4042847A80667AC5961E@MichaelSappPC>
From: "Michael Sapp" <wa3tts@verizon.net>
To: <rsgb_lf_group@blacksheep.org>
References: <5AB53C00.4447.2ABA73C6@mike.dennison.ntlworld.com> <5147CE521A69408F88362E122AA44FB8@MichaelSappPC> <f5529637-b73f-d6ba-c027-f2aa30f7b1f6@n1bug.com> <5AB6874C.80705@posteo.de>
In-Reply-To: <5AB6874C.80705@posteo.de>
Date: Sat, 24 Mar 2018 14:05:33 -0400
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Subject: Re: LF: Re: [Lowfer] Tx this w/e 136.172kHz
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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" <selberdenken@posteo.de>
To: <rsgb_lf_group@blacksheep.org>
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"<mike.dennison@ntlworld.com>
>>> To:<rsgb_lf_group@blacksheep.org>;<rsgb_lf_group@yahoogroups.co.uk>
>>> 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
>>>> ==========
>>>>
>>
>