Re: Topband: Shunt Feed help

[Gene Smar]

Bob:

 I'm guessing that the voltage on the 20M director is due to QRO
operation on 160M.  I recall reading an email from Natan, or at least he was
mentioned as the originator of the advice, here on TT maybe 15 years ago
that the C31XR antenna could have all the parasitic elements shorted to the
boom without adverse effects.  Something about the middle of the parasitics
being a voltage minimum.  I shorted the parasitics on my Skyhawk tribander
as the feedpoint is freakishly similar to F12's design to use it as top
loading for my shunt-fed tower on 160M.

 If you're interested, you can see a photo of the shorting assembly on
my Skyhawk at
http://photobucket.com/gallery/user/ersmar/media/bWVkaWFJZDoxMzI5NDU3Mg==/?r
ef=1 .  I fastened a 3/4 X 5 inch piece of aluminum flashing to the element
with a #10 SS self-tapping screw right through the center PVC insulator.  I
used a SS hose clamp to fasten the other end to the boom, using a small
amount of NoAlOx on the joint.  Then I taped the entire hose clamp.  Both
the Yagi and the shunt-fed tower seem to operate OK AFAICT.

 YMMV.

73 de
Gene Smar  AD3F



-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Marc
Wullaert ON4MA
Sent: Tuesday, October 10, 2017 1:43 PM
To: bob burton ; topband@contesting.com
Subject: Re: Topband: Shunt Feed help

Hi BoB,

be careful with the c31xr as the 20m reflector is on the far end. maximum
voltage present there and mine burned down at the isolator while my
freestanding tower (24m) with c31xr and 5m higher  a 40cd2 40m 2element beam
where shuntfed on 160m.

Best way is to ground the element or look for a better isolator

73

Marc ON4MA
https://www.facebook.com/marc.wullaert.5
- Original Message -
From: "bob burton via Topband" 
To: 
Sent: Tuesday, October 10, 2017 2:22 PM
Subject: Topband: Shunt Feed help


> Looking for some shunt feed wisdom from the list. Trying to shunt feed 25G

> tower ( 8-10ft sticks, 8ft flat top, base 18" out of the ground = total 
> tower 89.5 ft) has a F12 C31XR just above the thrust bearing (@90ft) with 
> 6ft 2" mast above the tribander with a F12 D140 dipole (@96ft). Based on 
> various archive reading I can't get a good sense of how much top loading I

> may have (some say only the boom, others say much more). That said I've 
> first tried a cage wire ( four 14ga wires spaced 6" apart) all the way at 
> the top of the tower spaced about 2ft out. Trying to dip this with an 
> Autek RF-1 yielded about 1.15 Mhz which didn't seem right. Cage was taken 
> down and tried just a single wire at a lower tap height of 60ft. Strangely

> enough I get about the same frequency but the Z dropped. Moving farther 
> down to 50ft again about the same frequency but again Z dropped. I'm 
> assuming the frequency readings are completely off and I'm getting 
> overload from nearby AM broadcast as I am surrounded by them. I'm unsure 
> now if I should continue trying tap points farther down the tower just 
> looking for the best Z or use some other approach. If anyone has 
> experience with how much top loading a C31XR could represent I could use 
> the graphs in ON4UNs book to perhaps get close, but I'm unsure what the 
> loading looks like and found no real answers searching the archives. Any 
> help appreciated to help eliminate many more trips on the tower looking 
> for the nearest 50 ohm spot. Tnx 73's Bob - N4PQX
> _
> Topband Reflector Archives - http://www.contesting.com/_topband 


---
Dit e-mailbericht is gecontroleerd op virussen met Avast antivirussoftware.
https://www.avast.com/antivirus

_
Topband Reflector Archives - http://www.contesting.com/_topband

_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Shunt Feed help

[Marc Wullaert ON4MA]

Hi BoB,

be careful with the c31xr as the 20m reflector is on the far end. maximum 
voltage present there and
mine burned down at the isolator while my freestanding tower (24m) with 
c31xr and 5m higher  a 40cd2 40m 2element beam

where shuntfed on 160m.

Best way is to ground the element or look for a better isolator

73

Marc ON4MA
https://www.facebook.com/marc.wullaert.5
- Original Message - 
From: "bob burton via Topband" 

To: 
Sent: Tuesday, October 10, 2017 2:22 PM
Subject: Topband: Shunt Feed help


Looking for some shunt feed wisdom from the list. Trying to shunt feed 25G 
tower ( 8-10ft sticks, 8ft flat top, base 18" out of the ground = total 
tower 89.5 ft) has a F12 C31XR just above the thrust bearing (@90ft) with 
6ft 2" mast above the tribander with a F12 D140 dipole (@96ft). Based on 
various archive reading I can't get a good sense of how much top loading I 
may have (some say only the boom, others say much more). That said I've 
first tried a cage wire ( four 14ga wires spaced 6" apart) all the way at 
the top of the tower spaced about 2ft out. Trying to dip this with an 
Autek RF-1 yielded about 1.15 Mhz which didn't seem right. Cage was taken 
down and tried just a single wire at a lower tap height of 60ft. Strangely 
enough I get about the same frequency but the Z dropped. Moving farther 
down to 50ft again about the same frequency but again Z dropped. I'm 
assuming the frequency readings are completely off and I'm getting 
overload from nearby AM broadcast as I am surrounded by them. I'm unsure 
now if I should continue trying tap points farther down the tower just 
looking for the best Z or use some other approach. If anyone has 
experience with how much top loading a C31XR could represent I could use 
the graphs in ON4UNs book to perhaps get close, but I'm unsure what the 
loading looks like and found no real answers searching the archives. Any 
help appreciated to help eliminate many more trips on the tower looking 
for the nearest 50 ohm spot. Tnx 73's Bob - N4PQX

_
Topband Reflector Archives - http://www.contesting.com/_topband 



---
Dit e-mailbericht is gecontroleerd op virussen met Avast antivirussoftware.
https://www.avast.com/antivirus

_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: Boring Report - 10 Oct 2017

[Tree]

Am very happy to report that 160 meters sounded like the good old days last
night with a solid opening to Europe.  SM5EDX acted like the beacon and was
heard for well over an hour with signals peaking 579.  HA8LNN, Zoli, who I
have never worked before on topband also had a good signal - peaking 569.
SM4DHF made it in the log as well.

Hopefully - this is sign that we will finally have a good season after
years of drought.

Antenna for TX is a top loaded tower - about 77 feet with a 60 foot loading
wire (have the Steppir elements retracted).  About 30 radials and a HiZ 4
square RX array.

SM5EDX did fire up his Viking and I fired up my Ranger - so we had a QSO
using Johnson equipment on each side - but K3's for RX and some help with
amplifiers.

73 Tree N6TR/7
Hillsboro, OR (about 50 miles West of the old Boring QTH)
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Shunt Feed help

[Brian Pease]

I have used NEC4 to model my short 50 ft tower for shunt feed on 160, 
80, and 40 meters.  It has a small triband beam with all elements 
grounded.  The 160m shunt wire goes to the top, of course, and NEC gave 
a good estimate of the impedance.  On 80m, my first guess was pretty 
close to 50 Ohms.  It took 3 tries on 40m where I was 3-4 ft off.
 I could extend the model to your height and lengthen my 3 elements to 
roughly simulate your beam & estimate the 160m shunt length. I assume 
that you have enough radials.


On 10/10/2017 8:22 AM, bob burton via Topband wrote:

  Looking for some shunt feed wisdom from the list. Trying to shunt feed 25G tower ( 8-10ft 
sticks, 8ft flat top, base 18" out of the ground = total tower 89.5 ft) has a F12 C31XR 
just above the thrust bearing (@90ft) with 6ft 2" mast above the tribander with a F12 
D140 dipole (@96ft). Based on various archive reading I can't get a good sense of how much top 
loading I may have (some say only the boom, others say much more). That said I've first tried 
a cage wire ( four 14ga wires spaced 6" apart) all the way at the top of the tower spaced 
about 2ft out. Trying to dip this with an Autek RF-1 yielded about 1.15 Mhz which didn't seem 
right. Cage was taken down and tried just a single wire at a lower tap height of 60ft. 
Strangely enough I get about the same frequency but the Z dropped. Moving farther down to 50ft 
again about the same frequency but again Z dropped. I'm assuming the frequency readings are 
completely off and I'm getting overload from nearby AM broadcast as I am surrounded by them. 
I'm unsure now if I should continue trying tap points farther down the tower just looking for 
the best Z or use some other approach. If anyone has experience with how much top loading a 
C31XR could represent I could use the graphs in ON4UNs book to perhaps get close, but I'm 
unsure what the loading looks like and found no real answers searching the archives. Any help 
appreciated to help eliminate many more trips on the tower looking for the nearest 50 ohm 
spot. Tnx 73's Bob - N4PQX
_
Topband Reflector Archives - http://www.contesting.com/_topband




_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: Shunt Feed help

[bob burton via Topband]

 Looking for some shunt feed wisdom from the list. Trying to shunt feed 25G 
tower ( 8-10ft sticks, 8ft flat top, base 18" out of the ground = total tower 
89.5 ft) has a F12 C31XR just above the thrust bearing (@90ft) with 6ft 2" mast 
above the tribander with a F12 D140 dipole (@96ft). Based on various archive 
reading I can't get a good sense of how much top loading I may have (some say 
only the boom, others say much more). That said I've first tried a cage wire ( 
four 14ga wires spaced 6" apart) all the way at the top of the tower spaced 
about 2ft out. Trying to dip this with an Autek RF-1 yielded about 1.15 Mhz 
which didn't seem right. Cage was taken down and tried just a single wire at a 
lower tap height of 60ft. Strangely enough I get about the same frequency but 
the Z dropped. Moving farther down to 50ft again about the same frequency but 
again Z dropped. I'm assuming the frequency readings are completely off and I'm 
getting overload from nearby AM broadcast as I am surrounded by them. I'm 
unsure now if I should continue trying tap points farther down the tower just 
looking for the best Z or use some other approach. If anyone has experience 
with how much top loading a C31XR could represent I could use the graphs in 
ON4UNs book to perhaps get close, but I'm unsure what the loading looks like 
and found no real answers searching the archives. Any help appreciated to help 
eliminate many more trips on the tower looking for the nearest 50 ohm spot. Tnx 
73's Bob - N4PQX 
_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: DXE TFS4 remote control?

[Jorge Diez - CX6VM]

Hello

How can I control remotely a TFS4 box to switch between four antennas?

It dont have USB or RS232 port, so maybe it is not possible?

thanks!

-- 
73,
Jorge
CX6VM/CW5W
_
Topband Reflector Archives - http://www.contesting.com/_topband