Hi guys .I am just wanted to confirm a question on coax shielding .
With 2-10 watts transmitting through rg213u could rf be escaping that could
cause desensitization to other radios .The repeater I have setup uses 9
meters of heliax from the main diplexer to ant and rg213u from the link
radio
At UHF, possibly, at VHF unlikely... you did not specify :-)
How close are the frequencies??? Lots of details left out for us to help.
If the freq's are within a few hundred kiloherts at vhf, antenna
separation is probably the issue...
More details please??
Doug
KD8B
kerincom wrote:
Hi
I think the coax causing issues is a reasonable assumption… and probably the
easiest thing to try.
Good luck.
73,
Mike
WM4B
_
From: Repeater-Builder@yahoogroups.com
[mailto:repeater-buil...@yahoogroups.com] On Behalf Of kerincom
Sent: Sunday, June 27, 2010 10:51 AM
Uhf the link is 517mhz and the repeater TX/rx pair is 473.475 and 478.675mhz
on one repeater and it is in a weak area with the main site so it has to
transmitt aprox 10 watts
Thank You,
Ian Wells,
Kerinvale Comaudio,
3A Murchison Street,Biloela.4715
Ph 0749922449 or 0409159932 or
Ian,
RG-213 coax can definitely contribute to desense, as can cheap connectors and
adapters. I suggest making up new jumpers using double-shielded coax such as
RG-400 or RG-214, and fit these jumpers with high-quality, crimp-on connectors
of the correct type on each end so that no adapters or
Jumpers between the TX ,rx and diplexer are rg223u .I thought of using
rg223u for the link radio to its antenna because it is only aprox 2-3meters
long but I felt I should try lmr400 because of the 100% shielding and the
link radio is just a standard radio that works in either rx or TX mode and
Ian;
It would seem that at uhf ~30mhz away cable leakage in the shed
would seem to be less likely than antenna to antenna interference. In
general it is the white noise generated by a transmitter on other
frequencies that is most likely to cause desense to a co located rx.
Assuming you
Would it be better to change the link radio to crystal instead of programmed
.It is currently a tait t2010
Thank You,
Ian Wells,
Kerinvale Comaudio,
3A Murchison Street,Biloela.4715
Ph 0749922449 or 0409159932 or 0749922574
www.kerinvalecomaudio.com.au
---Original
That's what I thought as I am currently using a 6ld450s notch diplexer and
should change it to a band pass/band reject diplexer .I tried a experiment
on site where I added 1 cavity inline with the receiver 478.675 and it
seemed to improve the problem .so that was going to be the next step but I
In theory most xtal radios are quieter than synthesized ones, but a
filter would seem to be the better thing to do as it really stops the
problem...even a bandpass can or 2 on the link radio would be acceptable
if a notch is not available.. I just offered a notch duplexer option as
they can be
Ok thanks .I will upgrade the diplexer and see how that goes I might have to
change all my repeaters the same .
Thank You,
Ian Wells,
Kerinvale Comaudio,
3A Murchison Street,Biloela.4715
Ph 0749922449 or 0409159932 or 0749922574
www.kerinvalecomaudio.com.au
---Original
While your logic is good on this, a Pass/Reject would help THAT
transmitter be more friendly to other receivers... and protect from raw
RF overload from other near-but-not-on-frequency transmitters... but the
noise geration issue ( part 2 of my general site comments) needs to be
plugged up on
Ian,
Since RG-223 is double-shielded cable and is similar in construction to RG-400,
it will be fine- provided you are using the connectors specifically made for
RG-223 which has a larger OD than RG-400. Please don't even think about using
LMR-400, 9913F, or any foil/braid cable because of
kerincom kerin...@... wrote:
Hi guys .I am just wanted to confirm a question on
coax shielding .
Simple answer... It's there and never seems to behave exactly
how you would expect it to.
With 2-10 watts transmitting through rg213u could RF be
escaping that could cause desensitization
Hi folks,
Am just finishing up the 6 meter heliax duplexer project,
and am getting some pretty good numbers. (3 'cans' on
each side, 90dB notch about 1.2dB 'pass' attenuation)..
Anyhow, I used some Johanson piston trimmers that I had,
but evidently they are a bit shy on the working voltage
Hello Group,
I need some help i am working on a MSF 5000 it has a TPN 1186b power supply i
need to have a battery back up what i want to do is get a 10 amp automatic
battery charger to keep the battery charged my question is what size of diode
and how many? would i need to go from the
Instead of piston trimmers you might want to try ARCO padders (postage stamp
size that can tolerate higher levels of rf current) or small air variable
capacitors. I have found both at reasonable prices at this site:
http://www.danssmallpartsandkits.net/
73 and aloha, Eric KH6CQ
--- On Sun,
Hi skip .The repeater radios are maxon sm4450sc and the link is a tait t2010
The test I have tried in the past have been definitely point to the link
being the problem as when we turn the link off the repeater works to its
full range but with it on we get desence.
We used to have the link closer
Hello all. I have a very good working GR1225 VHF repeater that I can't really
use. I would like to see if anyone would be interested in trading this vhf
radio for a good working uhf radio?. I just don't need the vhf anymore and have
my pair ready to go for UHF. Thanks and let me know.
Hi Eric,
I've been on Dan's site he has some good stuff.
I had the piston trimmers 'in-stock', so that's what
I used. (as did the original design) Was curious
About the WV of them.
Thanks,
Tim
-Original Message-
From: Eric Grabowski ejgrabow...@yahoo.com
Sent: Sunday, June 27, 2010
Hi Ian,
I think I'd be taking a close look at both transmitters with a spectrum
analyser and seeing if they are both suitable for repeater work. I'm not
familiar with either radio, but usually radios designed for duplex work go to a
lot more trouble with internal shielding than your average
Usually 250V. The more robust ones are rated for 500V, but generally as
capacitance range goes up working voltage goes down. See if you can find
some Russian surplus on ebay, those trimmers are built like a tank.
On Sun, Jun 27, 2010 at 5:58 PM, Tim tahr...@swtexas.net wrote:
Hi Eric,
I've
Currently I have no filters between the link transmitter and its antenna.
Thank You ,Ian Wells
Kerinvale Comaudio,
3A Murchison Street, Biloela.4715
Ph 0749922449 Mb 0409159932
Hm 0749922574 Fx 0749922767
www.kerinvalecomaudio.com.au
---Original Message---
From: Mark HARRISON
Date:
I am in need of 1/2 or 7/8 coax. I live in Olympia, WA and I am willing to
pick up within 100 miles or pay shipping to Olympia, WA.
I need 300 feet total or two pieces 150 feet.
Thanks,
Larry KC7CKO
Instead of piston trimmers you might want to try ARCO
padders (postage stamp size that can tolerate higher levels
of rf current) or small air variable capacitors. I have
nfound both at reasonable prices at this site:
A generic statement that has merit in this subject
Q is everything
1/4 super flex makes a pretty decent gimmick capacitor.
On Sun, Jun 27, 2010 at 10:16 PM, skipp025 skipp...@yahoo.com wrote:
Instead of piston trimmers you might want to try ARCO
padders (postage stamp size that can tolerate higher levels
of rf current) or small air variable capacitors. I
26 matches
Mail list logo
