SWR Issue

[buggiecar]

Hi All,
Need some advice on what to look for....I have a Diamond X50 mounted to an antenna mast that is grounded.
On 2 meters the SWR is almost non existent but on 70cm it is wicked high. The antenna is supposed to be good for both bands...did I overlook something? I am using RG8X coax..Running a Yaesu FT-857 as my base and and MFJ Duplexer. Thanks in advance. John W1COD

 

[gewecke]

John, you MAY have a defective X50. Did you just get the X50 or has it been up awhile? I've had the x50 in the past and used it for years with no issues, but there is a capacitor in the bottom which can fail, if it does it Can be repaired. 73, n9zas

 

[Weaksignal]

John,
RG-8X is fine for shortwave listening, but not so good for VHF+. 80 watts of power is about the upper limit on 440 MHz for RG-8X. The attenuation (dB per 100') is around 8.0... They're better choices for VHF. LMR 400 would be a better, even for a short run on 144 and 440 MHz.

 

[prcguy]

Did you check the SWR through the diplexer or direct to the antenna? I've run across a few bad diplexers out there. If SWR checks bad right to the antenna, especially with a short and known good length of coax then it may not be something you can't fix. Now that I read the original post again, why is there a diplexer in line? One antenna connector on the 857 is for HF through 6m and the other is for 2m and 440, you should just plug the X50 into the VHF/UHF port.
prcguy

 

[mass-man]

Good catch prcguy......I had an 857 for a bit and thought I remembered two antenna ports!!!!!

 

[buggiecar]

SONO***UN!!

Took out the duplexor...and sure enough 1 to .5 on 440 now and almost 1 to 1 on 2M!!
That was it!!! Thanks!!!

 

[prcguy]

Glad to hear nothing is actually broken.
prcguy

Took out the duplexor...and sure enough 1 to .5 on 440 now and almost 1 to 1 on 2M!!
That was it!!! Thanks!!!