chiwititsara
Member
- Joined
- Dec 2, 2015
- Messages
- 18
I have a small Chinese 10 watt mobile radio (Leixen VV898 or clone) mounted on the inside of a windowsill and an antenna directly outside the same window. The radio is powered by a ~13.8 volt DC switching regulated power supply connected by a few feet of 10 gauge copper wire. The radio has a plastic casing on its top and sides and an aluminum heatsink for its base.
I am having an issue where transmitting (VHF-high) at 10 watts causes the radio display to dim and measured voltage between the power supply and the radio drops dangerously low (8 volts or less at times, causing the display to dim or turn-off entirely).
TX'ing at 5 watts causes much less of a problem.
I believe the source of my problem is antenna RF entering the radio (and not DC power / power line interference) because the further I move the radio from the antenna, the less voltage drop I observe. There is no correlation with proximity to the DC power supply nor routing of the DC power lines.
With the radio installed right-side up (as designed) and separated ~10 feet horizontally / ~4 feet vertically from the antenna, the interference lessens but is still unacceptable, with voltage dropping 15% or more from the designed operating voltage.
Interestingly, at this same distance - and even much closer - I have found a simple solution that almost entirely mitigates my problems: Orienting the radio with the aluminum heatsink (base) facing the antenna and 'shielding' the transceiver's internals almost entirely cures the issue.
1. Does it seem correct that my problem is RF from the transceiver antenna entering the transceiver and causing my problems?
2. If so, what is a practical solution to prevent this that does not require entirely re-locating the antenna/radio beyond ~15 feet separation (any further and I would have to move to another room)?
Are there any recommended sheet metal enclosures / radio cabinets I might use to enclose the transceiver and block RF from entering the unit? I don't have a welder or scrap sheet metal just sitting around here but perhaps I could re-purpose some sort of metal enclosure designed for other electronics. Heat is not a real concern given the low duty cycles and low wattage I am using.
I am having an issue where transmitting (VHF-high) at 10 watts causes the radio display to dim and measured voltage between the power supply and the radio drops dangerously low (8 volts or less at times, causing the display to dim or turn-off entirely).
TX'ing at 5 watts causes much less of a problem.
I believe the source of my problem is antenna RF entering the radio (and not DC power / power line interference) because the further I move the radio from the antenna, the less voltage drop I observe. There is no correlation with proximity to the DC power supply nor routing of the DC power lines.
With the radio installed right-side up (as designed) and separated ~10 feet horizontally / ~4 feet vertically from the antenna, the interference lessens but is still unacceptable, with voltage dropping 15% or more from the designed operating voltage.
Interestingly, at this same distance - and even much closer - I have found a simple solution that almost entirely mitigates my problems: Orienting the radio with the aluminum heatsink (base) facing the antenna and 'shielding' the transceiver's internals almost entirely cures the issue.
1. Does it seem correct that my problem is RF from the transceiver antenna entering the transceiver and causing my problems?
2. If so, what is a practical solution to prevent this that does not require entirely re-locating the antenna/radio beyond ~15 feet separation (any further and I would have to move to another room)?
Are there any recommended sheet metal enclosures / radio cabinets I might use to enclose the transceiver and block RF from entering the unit? I don't have a welder or scrap sheet metal just sitting around here but perhaps I could re-purpose some sort of metal enclosure designed for other electronics. Heat is not a real concern given the low duty cycles and low wattage I am using.