That's great, Jim!! Sounds like it's working well!! Have fun! I'm sure you
will like it!
73,
Charlie, K4OTV
From: James Rodenkirch [mailto:rodenkirch_...@msn.com]
Sent: Sunday, August 25, 2013 9:53 AM
To: Charlie Cunningham
Subject: RE: Topband: Two 2:1 transformers to choose from
Ever since I added back-to-back 1N4148's between the preamp's input and
ground many years ago, I have never lost a transistor in my preamp. Before
that, it seemed that I was replacing it after nearly every thunderstorm.
A couple of years ago I changed it a little: I added a small incandescent
[mailto:topband-boun...@contesting.com] On Behalf Of Mike
Waters
Sent: Sunday, August 25, 2013 4:15 PM
To: James Rodenkirch; topband
Subject: Re: Topband: Two 2:1 transformers to choose from!!
Ever since I added back-to-back 1N4148's between the preamp's input and
ground many years ago, I have never
Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike
Waters
Sent: Sunday, August 25, 2013 4:15 PM
To: James Rodenkirch; topband
Subject: Re: Topband: Two 2:1 transformers to choose from!!
Ever since I added back-to-back 1N4148's between the preamp's input
So the general concessions is that 7:5 turns was better. Do is 15:7 turns
or 21:10 turns better? Whats best for 160M ?
--
Jim K9TF
_
Topband Reflector
All those turns are better for what? For the winding that's connected to
the coax (either 50 or 75 ohms), two turns is plenty.
And good luck stuffing all that wire inside the holes in those binocular
cores, especially if you use the recommended protective insulating liner.
:-)
73, Mike
Subject: Re: Topband: Two 2:1 transformers to choose from!!
All those turns are better for what? For the winding that's connected to
the coax (either 50 or 75 ohms), two turns is plenty.
And good luck stuffing all that wire inside the holes in those binocular
cores, especially if you use
I'm not sure what kind of material you made that from, but 3 or even 4
turns is OK for the low-Z winding on the #73 solid 2-hole cores we were
talking about earlier. It seemed to work well for you. :-)
Sometimes, we have to cascade two transformers to get to the Z ratio we
want.
73, Mike
Cc: topband
Subject: Re: Topband: Two 2:1 transformers to choose from!!
I'm not sure what kind of material you made that from, but 3 or even 4
turns is OK for the low-Z winding on the #73 solid 2-hole cores we were
talking about earlier. It seemed to work well for you. :-)
Sometimes, we have
P. 7-69 of Low Band Dxing (5th ed.) by ON4UN says a maximum of 4 turns on
the low-Z primary for binocular cores. It might work, but there are other
turns ratios you might try.
Here is a list of turns ratios for those cores I made:
http://www.w0btu.com/Binocular_core_turns_ratios.pdf
If you get a
Thanks, Mike - will try the 2:3 ratio one first!
Date: Thu, 22 Aug 2013 10:21:14 -0500
From: mikew...@gmail.com
To: rodenkirch_...@msn.com; topband@contesting.com
Subject: Re: Topband: Two 2:1 transformers to choose from!!
P. 7-69 of Low Band Dxing (5th ed.) by ON4UN says a maximum of 4
, August 22, 2013 2:00 PM
To: Mike Waters; topband
Subject: Re: Topband: Two 2:1 transformers to choose from!!
Thanks, Mike - will try the 2:3 ratio one first!
Date: Thu, 22 Aug 2013 10:21:14 -0500
From: mikew...@gmail.com
To: rodenkirch_...@msn.com; topband@contesting.com
Subject: Re: Topband
:1 transformers to choose from!!
P. 7-69 of Low Band Dxing (5th ed.) by ON4UN says a maximum of 4 turns on
the low-Z primary for binocular cores. It might work, but there are other
turns ratios you might try.
Here is a list of turns ratios for those cores I made:
http://www.w0btu.com
Since you wound both transformers, why not try them both, and see if you
can measure any difference? I' guessing you won't see much!
Unless the antenna system is starved for background noise, or the element is
in an end-fire phased array, it makes very little difference. The only real
That is EXACTLY what I have experienced here.
73, Mike
www.w0btu.com
On Thu, Aug 22, 2013 at 8:40 PM, Tom W8JI w...@w8ji.com wrote:
Two turns for 75 ohms is plenty for decent 100 kHz to 30 MHz performance.
_
Topband Reflector
I meant to add unless you need a certain impedance ratio.
On Thu, Aug 22, 2013 at 8:51 PM, Mike Waters mikew...@gmail.com wrote:
That is EXACTLY what I have experienced here.
73, Mike
www.w0btu.com
On Thu, Aug 22, 2013 at 8:40 PM, Tom W8JI w...@w8ji.com wrote:
Two turns for 75 ohms is
[mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI
Sent: Thursday, August 22, 2013 9:41 PM
To: 'topband'
Subject: Re: Topband: Two 2:1 transformers to choose from!!
Since you wound both transformers, why not try them both, and see if you
can measure any difference? I' guessing you won't see much
an
old tunable AMECO tube preamp to the RX antenna input of the FT-1000MP.
73,
Charlie, K4OTV
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike
Waters
Sent: Thursday, August 22, 2013 9:58 PM
To: topband
Subject: Re: Topband: Two 2:1 transformers
,
Charlie, K4OTV
From: Mike Waters [mailto:mikew...@gmail.com]
Sent: Thursday, August 22, 2013 10:41 PM
To: Charlie Cunningham; topband
Subject: Re: Topband: Two 2:1 transformers to choose from!!
This is the preamp I use. The circuit is from Solid State Design For the
Radio Amateur, C 1977
I have two impedance transformers wound on BN 73-202 cores that I can use for
the 2:1 impedance transformer I need for my FO0AAA delta receiving antenna.
One has a 2 turn and 3 turn winding- giving a 4:9 impedance ratio. The other
has a 7 turn and 5 turn winding, giving a 25:49 impedance
I received enuff info and thoughts to know I'll utilize the 5:7 winding
version. Thanks to all that replied!
72, Jim Rodenkirch K9JWV
From: rodenkirch_...@msn.com
To: topband@contesting.com
Subject: Two 2:1 transformers to choose from!!
Date: Wed, 21 Aug 2013 13:23:37 -0600
I have two
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