ARRL

KM3F

Joined: Thu, Mar 6th 2008, 13:50 Roles: N/A Moderates: N/A

Latest Topics

Topic Created Posts Views Last Activity
RF noise cancelling at VHF frequencies. Nov 20th 2012, 03:59 2 1,099 on 20/11/12
SWEEP testing a radio from the Mike jack. Jun 4th 2012, 04:57 3 702 on 4/6/12
Power Line Interference. Sep 23rd 2011, 01:07 6 1,738 on 11/5/12

Latest Posts

Topic Author Posted On
Two HF and one VHFwith a triplexer? W1VT on 30/11/13
I know this is an old thread but the subject needs more input.
First there is a multiband antenna on the market now.
Secondly the uses of di or triplexers is not the end all because they do not perform as well as is thought.
Everybody takes them for granted they work without issue.
A check with SWR and power meters on each band between the radio and the plexer will show a significant loss in pass through power and SWR may be high enough to cause transceiver power fold back such that nothing works very well..
Bottom line is not to use them unless you accept the results.
The other answer is to build them custom tuned to each band of use using low loss coaxial designs and adjustable tuned traps.
The ones available are cheap low grade broad band designs for the cost.
Good luck.
Six Meter FM KB5DOH on 31/3/13
What is the reason for doing FM in the SSB portion of the band plan that could not be done in the FM portion above 52 mhz?
Normally vertical polorization is used for net use on this band due to the wide area and close in area of coverge for the purposes of the net..
Expect some time to be challenged when working FM in 50.200 +/- range, especially when the band is open to long distance contacts.
You may do it many times and be legal but expect it may happen.
Let us know.
Good luck.
2M Mobile N2NBE on 20/12/12
I run a Yeasu FT 2800 in my 02 super crew.
There won't be any effects to the PCM.
Are you sure you have a 30 amp outlet?
Most of the ports are rated for 10 amps max.
The cigar lighter is a special socket and not reliable for regular plug uses due to the way the socket is made for that use.
The plugs normally used for assories are only rated for 10 amps.
My radio draws very close to 10 amps and would blow the fuse on high power after a few mintes talking.
Consult your owners manuel around page 200 for fuse / circuit rateings.
I custom built a filter that will pass at least 40 amps from a fused 30 amp # 10 feed direct from the battery.
It all works very well.
good luck.
RF noise cancelling at VHF frequencies. KM3F on 20/11/12
Would it be feasible to get a noise cancelling design to work on the same principle as the Time Wave ANC 4 using VHF construction methods?
This method uses a sampling antenna recieving the wideband noise and applying it 180 degrees out of phase for a null against the desired signal with the same noise, before the radio input..
I have an ANC 4 and works quite well up to 10 meters.
On 6 meters, not so well.
Would like to build one for 6 and 2 meters for power line noise control in weak signal work.
My beams point right into the noise area, very often.
Trying to get anything but known proven noise sources repaired is very tough if it is not very severe and outstanding.
Thanks.
KM3F
Tuning a mobile rig. Stan_TheGunNut on 7/11/12
Just to comment, a 50 ohm load that is near flat at the test frequency will show little to no swr with any meter used if there is no reflected power.
It's when there is reflected power, that accuracy vs design counts.
With a RS meter, on 2meters you may get the match down within acceptable limits but it may stiil be in some error as compaired to a meter designed for the frequency.
Said another way there is much more to SWR meter design than ,meets the eye.
On 70 cm. all bets are off using a RS meter designed for 11 meters.
On both bands the length of the sample line in the 11 meter unit is a substantial fraction of the wave length being measured so it makes a noticable difference in accuracy.
To sample reflected power over a 'small length' is the better way or use s torriod transformer designed for the frequency.
I bring this up to help a new Ham to know there is more to this than to offer a difference of opinion.
It's a learning hobby.
Good luck.

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