TRAM 1199 - glass mount

[c5corvette]

Not to start a debate about the effectiveness of glass mount antennas, there are enough posts with those already... ... so here is my thread:

The supplied cable is about 17 feet of RG58 with TNC to BNC and I am curious to know if anyone has used a different cable than the one provided? I am trying to determine if the length of the cable plays a factor in reception quality or if the type of cable matters.

I recently substituted an 8 foot run of RG400 with TNC to right angle BNC (amphenol connectors on professionally made cable) and the signal reception was actually degraded somewhat based on my non-scientific tests.

Anyone got thoughts or comments from either first hand knowledge or in theory???

Please help.

 

[Rt169Radio]

Yes,the length of the coax run can effect the signal quality.RG-8 coax is the best for vhf but its quite thick.RG58 coax is standard grade coax,but it will do nicely for a scanner antenna.Other thing is,try to get the shortest run you can with coax.Like I said the length of the coax run will effect signal quality.

 

[c5corvette]

I went from 17ft of RG58 that came with the antenna, to 8ft of RG400 - and reception capabilities decreased on VHF basline tests (WX band).

To rephrase my question about does the length of coax matter... I too thought shorter was always better, but is it possible that the glass mount antenna is requiring a specific length (17ft) of coax to make the glass coupling work the best?

 

[Rt169Radio]

I went from 17ft of RG58 that came with the antenna, to 8ft of RG400 - and reception capabilities decreased on VHF basline tests (WX band).

To rephrase my question about does the length of coax matter... I too thought shorter was always better, but is it possible that the glass mount antenna is requiring a specific length (17ft) of coax to make the glass coupling work the best?

It might be needing a specific length of coax to work the best,or it does the best with RG58 coax.

 

[popnokick]

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For receivers (not transmitting) I always install the glass mount antenna, run the included coax close to the scanner, lop off the excess, and attach a new connector (usually BNC matching the radio). Never have had performance degradation, and usually improvement over the coil of 6 or so extra feet of coax (and associated signal loss). If Tram or other mfr is designing the antenna and coax to be a single, integrated antenna that is tuned, it doesn't seem that the extra 6 feet coiled under your dashboard would help receive more signal or broader freq range. It might be possible to accidentally trim coax to the exact length of a standing wave null, but the odds against this in a receiver are pretty high. And the effect probably minimal. Now, if you botch the new connector installation and have an open or short... Well, that's a whole 'nother story.

 

[Placid1]

I was reading about this the other day. Some claim that specific cable lengths have a impact on the signal.

Exposing the 18' CB Coax Myth

I have read posts saying that if you get too much signal it can also cause issues that seem like worse reception on some channels . Usually using the scanners attenuator will fix that.