[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-20 Thread skipp025
Many thanks... makes it hard for me to be rotten all 
the time when people are nice. 
s. 


> "Ken Decker"  wrote:
> Skipp,
> 
> Here's the WA1ZDX info
> www.ccdx.org/zedyx/mods/db212.htm 
> 
> 
> Actually this one is on Repeater Builder
> http://www.repeater-builder.com/db/db-212-assembly-and-mounting-instructions-(andrew).pdf
> 
> 
> Spec from Andrew on the DB212
> http://www.stealth.ae/plugins/custompages/detinf.php?id=322&id_categories=115
> 
> 
> More Andrew info
> http://www.hol4g.com/webpdf/DBB_CAT29-PG318-319_01.PDF
> 
> 
> Info on modifying a DB201 and DB212 for 10 and 6 meters
> http://www.xanaduu.com/db201/
> 
> Ken WA6OSB
>




[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-19 Thread Ken Decker
Skipp,

Here's the WA1ZDX info
www.ccdx.org/zedyx/mods/db212.htm 


Actually this one is on Repeater Builder
http://www.repeater-builder.com/db/db-212-assembly-and-mounting-instructions-(andrew).pdf


Spec from Andrew on the DB212
http://www.stealth.ae/plugins/custompages/detinf.php?id=322&id_categories=115


More Andrew info
http://www.hol4g.com/webpdf/DBB_CAT29-PG318-319_01.PDF


Info on modifying a DB201 and DB212 for 10 and 6 meters
http://www.xanaduu.com/db201/

Ken WA6OSB

[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-18 Thread skipp025

Hi Ken, 

I'd be interested in the web page url for the WA1ZYX web page 
and the other information if you'd be willing to share it? 

I have a DB-212 cut and working on 6m and the same type of 
antenna on 2m with the director. I will as time allows 
document those antennas and make that information available 
to the group. 

s. 

> "Ken Decker"  wrote:
>
> Dave,
> 
> I found some info on DB212 cable lengths doing a Google search.  
> 
> A website by WA1ZYX has a couple of pages on modifying the DB212
> for 6 meters and also cable lengths/matching and spacing of the 
> folded dipoles.  No info on changing element spacing from tower
> leg.  This could affect the pattern.
> 
> Also found a 4 page article by Decibel Products titled DB212 Series.
> Good info on antenna patterns.
> 
> BTW, I've got a NOS DB225 cut for 75.70 MHz.  This is like a DB212 
> with a director.  It's got all the measurements for spacing for director, etc
> so this probably will be critical.  I was thinking of trying to extend the 
> elements for 6 meters.  Has anyone done this on a DB225?
> 
> Ken  WA6OSB
>




[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-18 Thread Ken Decker
Dave,

I found some info on DB212 cable lengths doing a Google search.  

A website by WA1ZYX has a couple of pages on modifying the DB212
for 6 meters and also cable lengths/matching and spacing of the 
folded dipoles.  No info on changing element spacing from tower
leg.  This could affect the pattern.

Also found a 4 page article by Decibel Products titled DB212 Series.
Good info on antenna patterns.

BTW, I've got a NOS DB225 cut for 75.70 MHz.  This is like a DB212 
with a director.  It's got all the measurements for spacing for director, etc
so this probably will be critical.  I was thinking of trying to extend the 
elements for 6 meters.  Has anyone done this on a DB225?

Ken  WA6OSB

Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-18 Thread Kevin Custer
Chuck Kelsey wrote:
> First, don't expect to land exactly where you expect simply by adjusting the 
> lengths to a specific dimension. You really need to place the antenna on a 
> tower to adjust properly and use an antenna analyzer.



Reminds me of my first experience with a Cushcraft AFM-4DA (4 bay 
exposed dipole array for 2M) about 30 years ago.

I put it on a nice galvanized mast and mounted it to a tall building 
free and clear of anything.  While the antenna worked - it really didn't 
perform any better than a 5/8 wave ground plane.  I realized that 
optimum gain was not being achieved because the dipoles were spaced 
around the galvanized support and weren't really "in phase" to help each 
other out.  OK, no problem, I'll put them in a line all above one 
another.  WOW, the gain in the direction where the dipoles were facing 
was fantastic - so, I fixed the "gain" problem - BUT I created another 
problem.  The null in the opposite direction was so deep that the system 
didn't work where I needed it to (I really needed omni coverage - I 
couldn't suffer with a null anywhere).  OK, no problem, I'll put the 
elements on a FIBERGLASS pole.  I bought a hefty fiberglass pipe and 
carefully mounted the Cushcraft array to it - mounting all of the 
dipoles above one another will retain the gain, and the fiberglass pipe 
won't create a null - problem solved right?  NOPE - a rubber duck would 
have performed better!

What happened?  

This type of array REQUIRES the element to be in the presence of a 
metallic mast - otherwise the impedance of the element isn't close to 50 
ohms.  I didn't have the ability then to measure return loss or actual 
impedance of the individual dipoles, but I can guarantee you it wasn't 
close to 50 ohms.  The antenna didn't work and the reflected power was 
awful.  I used a Bird and hand-held to feed one dipole  - while moving 
the distance between the dipole and the metal mast pipe - sure enough, 
when you got to the distance the mount was designed to give, the 
reflected was at a minimum.

SO   The distance between the antenna and the support varies the 
port impedance.

Bought a Sinclair SRL-229 (super stationmaster type) and life went on

Certainly on low band the concern of the elements exactly above on 
another is of a lesser concern because the difference in phase angle is 
likely less - so obtaining good low angle gain in an omni directional 
pattern is doable.

Kevin Custer


Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-18 Thread Chuck Kelsey
First, don't expect to land exactly where you expect simply by adjusting the 
lengths to a specific dimension. You really need to place the antenna on a 
tower to adjust properly and use an antenna analyzer.

The length of feedline from each antenna remains the same. You need to 
shorten the length of 35-ohm cable that attaches to the tee and heads toward 
your radio. This needs to be 1/4 wave taking the velocity factor of the 
cable into effect.

Chuck



- Original Message - 
From: "wa6ifi" 
To: 
Sent: Wednesday, November 18, 2009 12:04 AM
Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)


>I have a 2 loop DB212-2 which is cut for 48 MHz.  I want to use it for a 6M 
>repeater on 53.13.  I've shortened the loops to about 53".  Do I need to 
>shorten the length of the coax which runs from the antenna to the "T"? 
>What should be the length of the cable that runs from the "T" to the 
>feedline (cable C in instruction flyer.
>
> Thanks,
> Dave Novotny, WA6IFI
>
> --- In Repeater-Builder@yahoogroups.com, "Jeff DePolo"  wrote:
>>
>>
>> I have dimensional data for both Decibel and Celwave lowband folded 
>> dipoles
>> *somewhere*.  If there's interest I'll hunt for them.
>>
>> I think the Celwave design (with the "stingers") would be easier to
>> fabricate - no bending involved.
>>
>> --- Jeff WN3A
>>
>>
>> > -Original Message-
>> > From: Repeater-Builder@yahoogroups.com
>> > [mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025
>> > Sent: Sunday, November 15, 2009 10:57 AM
>> > To: Repeater-Builder@yahoogroups.com
>> > Subject: [Repeater-Builder] Re: Building Low Band Loop
>> > Antennas (DB-212)
>> >
>> >
>> >
>> >
>> > > "Chuck Kelsey"  wrote:
>> > > FYI - Sinclair got the extra bandwidth by stager tuning
>> > > the antenna element from the 1/4-wave matching transformer
>> > > that is inside the element. The trade-off was a decrease
>> > > in return loss (higher VSWR).
>> > > Chuck
>> > > WB2EDV
>> >
>> > Maybe... maybe not. I swept one just a short time back and
>> > the return loss was about 15.6 dB, which makes it a very nice
>> > usable animal.
>> >
>> > I've also had one in parts and the matching coax length was
>> > what I would have expected. Somewhere in my notes I have all
>> > the construction information recorded like I did on the Decibel
>> > Antennas...
>> >
>> > I've got a Decibel Loop at the old shop somewhere... if I can
>> > easily get it up high enough to throw a sweep on it I can
>> > report the results back.
>> >
>> > I'll have another HP Digital Sender (auto feed pdf scanner) on
>> > line within the month... then you'll have more information to
>> > chew over.
>> >
>> > cheers,
>> > s.
>> >
>> >
>> >
>> >
>> >
>> > No virus found in this incoming message.
>> > Checked by AVG - www.avg.com
>> > Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release
>> > Date: 11/15/09 07:50:00
>> >
>> >
>> >
>>
>
>
>
>
> 
>
>
>
> Yahoo! Groups Links
>
>
>






No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.707 / Virus Database: 270.14.71/2510 - Release Date: 11/17/09 
14:26:00



[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-17 Thread wa6ifi
I have a 2 loop DB212-2 which is cut for 48 MHz.  I want to use it for a 6M 
repeater on 53.13.  I've shortened the loops to about 53".  Do I need to 
shorten the length of the coax which runs from the antenna to the "T"?  What 
should be the length of the cable that runs from the "T" to the feedline (cable 
C in instruction flyer.

Thanks,
Dave Novotny, WA6IFI

--- In Repeater-Builder@yahoogroups.com, "Jeff DePolo"  wrote:
>
> 
> I have dimensional data for both Decibel and Celwave lowband folded dipoles
> *somewhere*.  If there's interest I'll hunt for them.  
> 
> I think the Celwave design (with the "stingers") would be easier to
> fabricate - no bending involved.
> 
>   --- Jeff WN3A
>  
> 
> > -Original Message-
> > From: Repeater-Builder@yahoogroups.com 
> > [mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025
> > Sent: Sunday, November 15, 2009 10:57 AM
> > To: Repeater-Builder@yahoogroups.com
> > Subject: [Repeater-Builder] Re: Building Low Band Loop 
> > Antennas (DB-212)
> > 
> >   
> > 
> > 
> > > "Chuck Kelsey"  wrote:
> > > FYI - Sinclair got the extra bandwidth by stager tuning 
> > > the antenna element from the 1/4-wave matching transformer 
> > > that is inside the element. The trade-off was a decrease 
> > > in return loss (higher VSWR).
> > > Chuck
> > > WB2EDV
> > 
> > Maybe... maybe not. I swept one just a short time back and 
> > the return loss was about 15.6 dB, which makes it a very nice 
> > usable animal. 
> > 
> > I've also had one in parts and the matching coax length was 
> > what I would have expected. Somewhere in my notes I have all 
> > the construction information recorded like I did on the Decibel 
> > Antennas...
> > 
> > I've got a Decibel Loop at the old shop somewhere... if I can 
> > easily get it up high enough to throw a sweep on it I can 
> > report the results back. 
> > 
> > I'll have another HP Digital Sender (auto feed pdf scanner) on 
> > line within the month... then you'll have more information to 
> > chew over. 
> > 
> > cheers, 
> > s. 
> > 
> > 
> > 
> > 
> > 
> > No virus found in this incoming message.
> > Checked by AVG - www.avg.com
> > Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release 
> > Date: 11/15/09 07:50:00
> > 
> > 
> >
>




Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-17 Thread Neal Newman
Yep  I have 2  6 meter repeaters  I would be interested in the data to build a 
few DB-212 antennas

 Neal  KA2CAF

--- On Tue, 11/17/09, Adam T. Cately  wrote:

> From: Adam T. Cately 
> Subject: Re: [Repeater-Builder] Re: Building Low Band Loop Antennas  (DB-212)
> To: Repeater-Builder@yahoogroups.com
> Date: Tuesday, November 17, 2009, 6:45 AM
>    If'n I remember
> correctly...
> 
>    Fred Vobbe built his own 6m loop antennas
> for his repeater array - 
> maybe someone could arm-twist him for his story about the
> antennas and
> harness.
> 
>    (Sorry Fred - I know you'se busy...)
> 
> 
> At 06:28 PM 11/16/09 -, you wrote:
> >Yes please Jeff... 
> >
> >thanks
> >skipp 
> >
> >
> >> "Jeff DePolo"  wrote:
> >> I have dimensional data for both Decibel and
> Celwave 
> >> lowband folded dipoles *somewhere*.  If
> there's interest 
> >> I'll hunt for them.  
> >> 
> >> I think the Celwave design (with the "stingers")
> would be easier to
> >> fabricate - no bending involved.
> >> 
> >>        
>         --- Jeff WN3A
> >>  
> 
>    - Adam - 
> 
>    
> 
>   
> 
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
>     repeater-builder-fullfeatu...@yahoogroups.com
> 
> 
> 


  


Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-17 Thread Adam T. Cately
   If'n I remember correctly...

   Fred Vobbe built his own 6m loop antennas for his repeater array - 
maybe someone could arm-twist him for his story about the antennas and
harness.

   (Sorry Fred - I know you'se busy...)


At 06:28 PM 11/16/09 -, you wrote:
>Yes please Jeff... 
>
>thanks
>skipp 
>
>
>> "Jeff DePolo"  wrote:
>> I have dimensional data for both Decibel and Celwave 
>> lowband folded dipoles *somewhere*.  If there's interest 
>> I'll hunt for them.  
>> 
>> I think the Celwave design (with the "stingers") would be easier to
>> fabricate - no bending involved.
>> 
>>  --- Jeff WN3A
>>  

   - Adam - 

   

  



[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-16 Thread skipp025
Yes please Jeff... 

thanks
skipp 


> "Jeff DePolo"  wrote:
> I have dimensional data for both Decibel and Celwave 
> lowband folded dipoles *somewhere*.  If there's interest 
> I'll hunt for them.  
> 
> I think the Celwave design (with the "stingers") would be easier to
> fabricate - no bending involved.
> 
>   --- Jeff WN3A
>  
> 
> > -Original Message-
> > From: Repeater-Builder@yahoogroups.com 
> > [mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025
> > Sent: Sunday, November 15, 2009 10:57 AM
> > To: Repeater-Builder@yahoogroups.com
> > Subject: [Repeater-Builder] Re: Building Low Band Loop 
> > Antennas (DB-212)
> > 
> >   
> > 
> > 
> > > "Chuck Kelsey"  wrote:
> > > FYI - Sinclair got the extra bandwidth by stager tuning 
> > > the antenna element from the 1/4-wave matching transformer 
> > > that is inside the element. The trade-off was a decrease 
> > > in return loss (higher VSWR).
> > > Chuck
> > > WB2EDV
> > 
> > Maybe... maybe not. I swept one just a short time back and 
> > the return loss was about 15.6 dB, which makes it a very nice 
> > usable animal. 
> > 
> > I've also had one in parts and the matching coax length was 
> > what I would have expected. Somewhere in my notes I have all 
> > the construction information recorded like I did on the Decibel 
> > Antennas...
> > 
> > I've got a Decibel Loop at the old shop somewhere... if I can 
> > easily get it up high enough to throw a sweep on it I can 
> > report the results back. 
> > 
> > I'll have another HP Digital Sender (auto feed pdf scanner) on 
> > line within the month... then you'll have more information to 
> > chew over. 
> > 
> > cheers, 
> > s. 
> > 
> > 
> > 
> > 
> > 
> > No virus found in this incoming message.
> > Checked by AVG - www.avg.com
> > Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release 
> > Date: 11/15/09 07:50:00
> > 
> > 
> >
>




RE: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-15 Thread Jeff DePolo

I have dimensional data for both Decibel and Celwave lowband folded dipoles
*somewhere*.  If there's interest I'll hunt for them.  

I think the Celwave design (with the "stingers") would be easier to
fabricate - no bending involved.

--- Jeff WN3A
 

> -Original Message-
> From: Repeater-Builder@yahoogroups.com 
> [mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025
> Sent: Sunday, November 15, 2009 10:57 AM
> To: Repeater-Builder@yahoogroups.com
> Subject: [Repeater-Builder] Re: Building Low Band Loop 
> Antennas (DB-212)
> 
>   
> 
> 
> > "Chuck Kelsey"  wrote:
> > FYI - Sinclair got the extra bandwidth by stager tuning 
> > the antenna element from the 1/4-wave matching transformer 
> > that is inside the element. The trade-off was a decrease 
> > in return loss (higher VSWR).
> > Chuck
> > WB2EDV
> 
> Maybe... maybe not. I swept one just a short time back and 
> the return loss was about 15.6 dB, which makes it a very nice 
> usable animal. 
> 
> I've also had one in parts and the matching coax length was 
> what I would have expected. Somewhere in my notes I have all 
> the construction information recorded like I did on the Decibel 
> Antennas...
> 
> I've got a Decibel Loop at the old shop somewhere... if I can 
> easily get it up high enough to throw a sweep on it I can 
> report the results back. 
> 
> I'll have another HP Digital Sender (auto feed pdf scanner) on 
> line within the month... then you'll have more information to 
> chew over. 
> 
> cheers, 
> s. 
> 
> 
> 
> 
> 
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release 
> Date: 11/15/09 07:50:00
> 
> 
> 



Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-15 Thread Chuck Kelsey
I was hoping that Burt would chime in.

Chuck
WB2EDV



- Original Message - 
From: "Burt Lang" 
To: 
Sent: Sunday, November 15, 2009 11:57 AM
Subject: Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)


> The low-band loop from Sinclair (SRL 110) was not nearly as wide band as
> the Hi band (SRL210) and UHF models (SRL310).  The latter were designed
> to be mounted either half wave or quarter wave from the tower or mast.
> In the case of the low band loop a half wave would have put the loop 10
> ft from the mast, which would be structually unsound.  The SRL110 were
> normally mounted about 3 ft or so from the mast which is 1/8 wave.  This
> would result in a lower impedance (<200 ohms loop impedance)  requiring
> 93 ohm coax as an internal matching transformer (the SRL210 and 310
> series use 125 ohm matching coax).  It also would be much more sensitive
> to spacing from the mast or tower.
>
> At least that has been my experience with the low band loops.
>
> Burt  VE2BMQ
>



Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-15 Thread Burt Lang
The low-band loop from Sinclair (SRL 110) was not nearly as wide band as 
the Hi band (SRL210) and UHF models (SRL310).  The latter were designed 
to be mounted either half wave or quarter wave from the tower or mast. 
In the case of the low band loop a half wave would have put the loop 10 
ft from the mast, which would be structually unsound.  The SRL110 were 
normally mounted about 3 ft or so from the mast which is 1/8 wave.  This 
would result in a lower impedance (<200 ohms loop impedance)  requiring 
93 ohm coax as an internal matching transformer (the SRL210 and 310 
series use 125 ohm matching coax).  It also would be much more sensitive 
to spacing from the mast or tower.

At least that has been my experience with the low band loops.

Burt  VE2BMQ

Chuck Kelsey wrote:
> FYI - Sinclair got the extra bandwidth by stager tuning the antenna element 
> from the 1/4-wave matching transformer that is inside the element. The 
> trade-off was a decrease in return loss (higher VSWR).
> 
> Chuck
> WB2EDV
> 
> 
> 
> 
> - Original Message - 
> From: "skipp025" 
> To: 
> Sent: Sunday, November 15, 2009 10:15 AM
> Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
> 
> 
>> If you're building a Low-Band Loop Antenna from scratch...
>> forget the DB-212 and copy the Sinclair Version. The
>> Sinclair Low-Band loop has a lot wider band-width and it's
>> pretty much the same design... if properly done easier to
>> construct hardware wise.
>>
>> s.
>>
>>
>>> "cruizzer77"  wrote:
>>>
>>>
>>>
>>> Thanks for the info. Somewhere else I read that from the mount to the 
>>> outer edge the length should be 51 inches, this will be about the same as 
>>> 52.5 inches from center to outer edge.
>>>
>>> But to build one from scratch I need more info, radius of the loop, 
>>> diameter of the tube, coupling etc. Of course these can be calculated 
>>> from formulas, but as the DB212 seems to be a particular good design it 
>>> would be interesting to know.
>>>
>>>
>>>
>>>
>>>
>>> --- In Repeater-Builder@yahoogroups.com, "JOHN MACKEY"  wrote:
>>>> I converted one about 15 years ago for use on 6 meters.  It measured 
>>>> 52.5
>>>> inches from center to outer edge.
>>>>
>>>> -- Original Message --
>>>> Received: Sat, 14 Nov 2009 10:41:05 AM PST
>>>> From: "cruizzer77" 
>>>> To: Repeater-Builder@yahoogroups.com
>>>> Subject: [Repeater-Builder] DB-212 detailed info wanted
>>>>
>>>>> Does anyone have detailed info about the DB-212 antenna (converted to 
>>>>> 6m)
>>>> that make it possible to build one from scratch?
>>>>> All the measures and info about the mount and feed point are 
>>>>> interesting in
>>>> the first place.
>>>>> 73 de Martin HB9TZW
>>>>>
>>>>>
>>>>>
>>>>>
>>
>>
>>
>> 
>>
>>
>>
>> Yahoo! Groups Links
>>
>>
>>
> 
> 
> 
> 
> 
> 
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.707 / Virus Database: 270.14.66/2504 - Release Date: 11/15/09 
> 02:50:00
> 
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
> 


Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-15 Thread Chuck Kelsey
I've seen some return loss figures in the 30-40 dB range on the Decibel 
antenna. However, sweep one and report back.

Chuck
WB2EDV


- Original Message - 
From: "skipp025" 
To: 
Sent: Sunday, November 15, 2009 10:57 AM
Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)


>
>> "Chuck Kelsey"  wrote:
>> FYI - Sinclair got the extra bandwidth by stager tuning
>> the antenna element from the 1/4-wave matching transformer
>> that is inside the element. The trade-off was a decrease
>> in return loss (higher VSWR).
>> Chuck
>> WB2EDV
>
> Maybe... maybe not.  I swept one just a short time back and
> the return loss was about 15.6 dB, which makes it a very nice
> usable animal.
>
> I've also had one in parts and the matching coax length was
> what I would have expected. Somewhere in my notes I have all
> the construction information recorded like I did on the Decibel
> Antennas...
>
> I've got a Decibel Loop at the old shop somewhere... if I can
> easily get it up high enough to throw a sweep on it I can
> report the results back.
>
> I'll have another HP Digital Sender (auto feed pdf scanner) on
> line within the month... then you'll have more information to
> chew over.
>
> cheers,
> s.



[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-15 Thread skipp025

> "Chuck Kelsey"  wrote:
> FYI - Sinclair got the extra bandwidth by stager tuning 
> the antenna element from the 1/4-wave matching transformer 
> that is inside the element. The trade-off was a decrease 
> in return loss (higher VSWR).
> Chuck
> WB2EDV

Maybe... maybe not.  I swept one just a short time back and 
the return loss was about 15.6 dB, which makes it a very nice 
usable animal. 

I've also had one in parts and the matching coax length was 
what I would have expected. Somewhere in my notes I have all 
the construction information recorded like I did on the Decibel 
Antennas...

I've got a Decibel Loop at the old shop somewhere... if I can 
easily get it up high enough to throw a sweep on it I can 
report the results back. 

I'll have another HP Digital Sender (auto feed pdf scanner) on 
line within the month... then you'll have more information to 
chew over. 

cheers, 
s. 

 



Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-15 Thread Chuck Kelsey
FYI - Sinclair got the extra bandwidth by stager tuning the antenna element 
from the 1/4-wave matching transformer that is inside the element. The 
trade-off was a decrease in return loss (higher VSWR).

Chuck
WB2EDV




- Original Message - 
From: "skipp025" 
To: 
Sent: Sunday, November 15, 2009 10:15 AM
Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)


> If you're building a Low-Band Loop Antenna from scratch...
> forget the DB-212 and copy the Sinclair Version. The
> Sinclair Low-Band loop has a lot wider band-width and it's
> pretty much the same design... if properly done easier to
> construct hardware wise.
>
> s.
>
>
>> "cruizzer77"  wrote:
>>
>>
>>
>> Thanks for the info. Somewhere else I read that from the mount to the 
>> outer edge the length should be 51 inches, this will be about the same as 
>> 52.5 inches from center to outer edge.
>>
>> But to build one from scratch I need more info, radius of the loop, 
>> diameter of the tube, coupling etc. Of course these can be calculated 
>> from formulas, but as the DB212 seems to be a particular good design it 
>> would be interesting to know.
>>
>>
>>
>>
>>
>> --- In Repeater-Builder@yahoogroups.com, "JOHN MACKEY"  wrote:
>> >
>> > I converted one about 15 years ago for use on 6 meters.  It measured 
>> > 52.5
>> > inches from center to outer edge.
>> >
>> > -- Original Message --
>> > Received: Sat, 14 Nov 2009 10:41:05 AM PST
>> > From: "cruizzer77" 
>> > To: Repeater-Builder@yahoogroups.com
>> > Subject: [Repeater-Builder] DB-212 detailed info wanted
>> >
>> > > Does anyone have detailed info about the DB-212 antenna (converted to 
>> > > 6m)
>> > that make it possible to build one from scratch?
>> > >
>> > > All the measures and info about the mount and feed point are 
>> > > interesting in
>> > the first place.
>> > >
>> > > 73 de Martin HB9TZW
>> > >
>> > >
>> > >
>> > >
>> >
>>
>
>
>
>
> 
>
>
>
> Yahoo! Groups Links
>
>
>






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[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

2009-11-15 Thread skipp025
If you're building a Low-Band Loop Antenna from scratch... 
forget the DB-212 and copy the Sinclair Version. The 
Sinclair Low-Band loop has a lot wider band-width and it's 
pretty much the same design... if properly done easier to 
construct hardware wise. 

s. 


> "cruizzer77"  wrote:
>
> 
> 
> Thanks for the info. Somewhere else I read that from the mount to the outer 
> edge the length should be 51 inches, this will be about the same as 52.5 
> inches from center to outer edge.
> 
> But to build one from scratch I need more info, radius of the loop, diameter 
> of the tube, coupling etc. Of course these can be calculated from formulas, 
> but as the DB212 seems to be a particular good design it would be interesting 
> to know.
> 
> 
> 
> 
> 
> --- In Repeater-Builder@yahoogroups.com, "JOHN MACKEY"  wrote:
> >
> > I converted one about 15 years ago for use on 6 meters.  It measured 52.5
> > inches from center to outer edge.
> > 
> > -- Original Message --
> > Received: Sat, 14 Nov 2009 10:41:05 AM PST
> > From: "cruizzer77" 
> > To: Repeater-Builder@yahoogroups.com
> > Subject: [Repeater-Builder] DB-212 detailed info wanted
> > 
> > > Does anyone have detailed info about the DB-212 antenna (converted to 6m)
> > that make it possible to build one from scratch?
> > > 
> > > All the measures and info about the mount and feed point are interesting 
> > > in
> > the first place.
> > > 
> > > 73 de Martin HB9TZW
> > > 
> > > 
> > > 
> > >
> >
>