Help VHF antenna, transmit with no receive
- Thread starter jwreich
- Start date
I wanted to report back on this testing.
I've had a chance to test with a local HAM that has the same antenna(s) but Yeasu radios. I use Retevis HT's. My friend had a Yeasu mobile unit mounted to the same comet antenna and mag mount as me. His HT, Yeasu FT70DR, uses a Signal Stick and has a signal stick mag mount on his truck for in-cab operation of the FT70DR.
Having a mobile unit, he had not tested with the FT70DR as a primary mobile radio with VHF repeaters, but it exhibited some of the same issues as my HT's.
He could TX and RX the VHF repeater with the ratio mounted antenna. When he connected his mag mount antenna he could TX, but there was no RX using the Signal Stick mag mount.
The VHF repeater is mounted at the top of a 648' tower 5 miles away. There is no reason RX should be impacted. We moved his FT70DR to my finder mounted Comet and he could receive, but the signal was weak.
After this testing, I believe my HT's experience reduced RX sensitivity on VHF when connected to vehicle mounted antennas. I can monitor the repeater on my HT and could barely him or other traffic. I could hear the Repeater identification just fine, but the audio was very week and scratchy on my HT. Traffic from other is hit and miss. Some is weak while other traffic is strong.
I'm not sure why UHF repeaters are so clear and strong, but I'm giving up on VHF operation. I'll eventually invest in a mobile unit for my truck and will most likely be very happy. Until then, I'll keep my rubber duck HT.
I appreciate all of the suggestions and recommendations.
I've had a chance to test with a local HAM that has the same antenna(s) but Yeasu radios. I use Retevis HT's. My friend had a Yeasu mobile unit mounted to the same comet antenna and mag mount as me. His HT, Yeasu FT70DR, uses a Signal Stick and has a signal stick mag mount on his truck for in-cab operation of the FT70DR.
Having a mobile unit, he had not tested with the FT70DR as a primary mobile radio with VHF repeaters, but it exhibited some of the same issues as my HT's.
He could TX and RX the VHF repeater with the ratio mounted antenna. When he connected his mag mount antenna he could TX, but there was no RX using the Signal Stick mag mount.
The VHF repeater is mounted at the top of a 648' tower 5 miles away. There is no reason RX should be impacted. We moved his FT70DR to my finder mounted Comet and he could receive, but the signal was weak.
After this testing, I believe my HT's experience reduced RX sensitivity on VHF when connected to vehicle mounted antennas. I can monitor the repeater on my HT and could barely him or other traffic. I could hear the Repeater identification just fine, but the audio was very week and scratchy on my HT. Traffic from other is hit and miss. Some is weak while other traffic is strong.
I'm not sure why UHF repeaters are so clear and strong, but I'm giving up on VHF operation. I'll eventually invest in a mobile unit for my truck and will most likely be very happy. Until then, I'll keep my rubber duck HT.
I appreciate all of the suggestions and recommendations.
It was a thought that crossed my mind, but when I would monitor the frequency, the static was loud an clear.
I drove all over town one day looking for a errant signal on the input of one of our repeaters
it would vary in strength but I could never figure out a pattern
when I got back home shut off the van and fiddled with the radio for a bit
a couple minutes later the signal shut off
feeling dejected I opened the door of the van, with out the key in the ignition
and poof the signal was back
any time you opened the door the body computer came on and made the interference
it would vary in strength but I could never figure out a pattern
when I got back home shut off the van and fiddled with the radio for a bit
a couple minutes later the signal shut off
feeling dejected I opened the door of the van, with out the key in the ignition
and poof the signal was back
any time you opened the door the body computer came on and made the interference
K9WKJ, Thanks for sharing. I can pick up some inference when I move my HT close to the truck (no key, not running, door opened) and I monitor GRMS frequencies. I can't tell what frequency is the issue as it seem broad.
I can also confirm that relatively local simplex on VHF channels are loud and clear.
How did you shield your gear from the body computer issues?
I'll test on a different, 2002 excursion, that I know doesn't have body computers and a solid steel structure to see if it exhibits the same issues when testing.
I can also confirm that relatively local simplex on VHF channels are loud and clear.
How did you shield your gear from the body computer issues?
I'll test on a different, 2002 excursion, that I know doesn't have body computers and a solid steel structure to see if it exhibits the same issues when testing.
Thanks, yes, I have confirmed the PL code is accurate. That's what funny, I can installed the Diamond RH707 rubber duck and hear fine. My issue is connecting to the Diamond finder mounted antenna. I get great transmit audio reports, but I can't hear any of the responses.
nd5y
Member
It's probably the same thing that happens to many Baofeng an other cheap low end transciever-on-a-chip radios.
In today's electronics-ridden world, there are many devices that act as "unintentional emitters" and can potentially cause problems with reception. This is especially true of modern motor vehicles.
I have a similar problem with a strong, on-frequency signal in my garage, but only when the car is running. But when I remove the car from the confines of the garage, the signal is no longer present. Apparently, the car itself is only part of the problem, but I haven't yet discovered the other part.
I have a similar problem with a strong, on-frequency signal in my garage, but only when the car is running. But when I remove the car from the confines of the garage, the signal is no longer present. Apparently, the car itself is only part of the problem, but I haven't yet discovered the other part.
Could be, but it would also be not so cheap Yeasu FT70DR radios too because my friend's radio showed inconsistency on RX.
G7RUX
Active Member
- Joined
- Jul 14, 2021
- Messages
- 524
I think I would be having a sniff around with a spectrum analyser on that antenna to see what I could see…it sounds like there might be strong OOB signals clobbering the receiver but it’s really difficult to diagnose things like this remotely.
Howdy
Get with a local Elmer and and see if anyone has a dual band J-Pole (on Field Antenna) and a tri-pod with a short mast. Get a small 12 VDC Battery and go to a local park or an unused large parking lot (School, City Building...) and set up of a Field Test far away from any cars or trucks to eliminate that possible RFI issue set.
Use Coax and connectors (known good or Dummy Load Tested) from others to look at Fault-Isolation in the signal train.
Could be as simple as a faulty connector, marginal coax (damaged during install or routing) or the Antenna that might be a co-linear type that has an intermittent issue inside the radome...
Remember, if you are seeing a "good" Tx SWR is the same "good" SWR you can also see on a Dummy Load too.
Test all your Radio's with a Field Antenna set up (not yours) and confirm you still are receiving VHF NOAA Wx Broadcast and try some Simplex Radio checks between your Filed set up and an HT in the area.
This would assist in validating if the Radio has an issue, Factory Reset might be required, after you back-up the radio Memory, etc...
A local Ham Club likely has members that can either "Bench Test" or assist and perhaps test your Radio alone on a known good installation.
Try to isolate every single part and use other folks Antenna, Coax, Connectors and Power sources to Fault-Isolate - you might have more that one issue (crimped / bent coax cable - faulty connector....etc..) and trying to trouble shoot is very difficult as one problem can mask the other at times...
Hope you figure it out.
Get with a local Elmer and and see if anyone has a dual band J-Pole (on Field Antenna) and a tri-pod with a short mast. Get a small 12 VDC Battery and go to a local park or an unused large parking lot (School, City Building...) and set up of a Field Test far away from any cars or trucks to eliminate that possible RFI issue set.
Use Coax and connectors (known good or Dummy Load Tested) from others to look at Fault-Isolation in the signal train.
Could be as simple as a faulty connector, marginal coax (damaged during install or routing) or the Antenna that might be a co-linear type that has an intermittent issue inside the radome...
Remember, if you are seeing a "good" Tx SWR is the same "good" SWR you can also see on a Dummy Load too.
Test all your Radio's with a Field Antenna set up (not yours) and confirm you still are receiving VHF NOAA Wx Broadcast and try some Simplex Radio checks between your Filed set up and an HT in the area.
This would assist in validating if the Radio has an issue, Factory Reset might be required, after you back-up the radio Memory, etc...
A local Ham Club likely has members that can either "Bench Test" or assist and perhaps test your Radio alone on a known good installation.
Try to isolate every single part and use other folks Antenna, Coax, Connectors and Power sources to Fault-Isolate - you might have more that one issue (crimped / bent coax cable - faulty connector....etc..) and trying to trouble shoot is very difficult as one problem can mask the other at times...
Hope you figure it out.
Similar threads
