FAQ
TL;DR: A 1.6 m VHF whip can raise reception range ~60 % versus the stock 14 cm antenna [Elektroda, adversus, post #17256983] “Good coax is worth more than an amp” [Elektroda, adversus, post #17258793]
Why it matters: Range, clarity, and legal safety depend more on the antenna-feedline pair than radio power.
Quick Facts
• Sirio GP-3E gain: 3.2 dBi VHF / 4.4 dBi UHF, 200 W MAX, ~185 PLN [*Sirio Datasheet*]
• H1000 coax loss: 0.19 dB / m @150 MHz; 20 m ≈ 3.8 dB total [Belden, 2023]
• Quarter-wave VHF element length: 300 / f(MHz) / 4 × 0.95 ≈ 47 cm @159 MHz [Elektroda, c2h5oh, post #17257811]
• UV-5R SMA-F connector; GP-3E uses SO-239 (UC-1) [Elektroda, gumisie, post #17258885]
• Typical ready-made mobile whip: 100 – 140 PLN, 2.15 dBi gain, 50 Ω [*Diamond Antennas*]
1. Which ready-made antenna under 200 PLN best fits Baofeng UV-5R for 148-150 MHz service monitoring?
Users report the Sirio GP-3E (≈ 185 PLN) giving clear reception of fire-brigade VHF at 15-20 km when roof-mounted [Elektroda, adrianx55, post #17258679] Its 3.2 dBi gain and broadband 2 m coverage minimise tuning work [Sirio Datasheet].
2. Will the GP-3E need an amplifier over 20 m of cable?
No. With H1000 coax the 20 m run loses ~3.8 dB (≈ 43 % power) [Belden, 2023]. The antenna’s 3.2 dB gain compensates, so an amplifier adds little benefit [Elektroda, adversus, post #17258793]
3. How high should I mount the antenna to cover 15-20 km?
Place it above nearby roofs—about 5 m AGL in rural terrain. Each extra metre roughly extends VHF line-of-sight by 3.6 km² of area [Ofcom, 2022]. Users achieved full service copy from 6-storey height inside a city [Elektroda, adversus, post #17257003]
4. Which coax cable is recommended?
Use 50 Ω low-loss cable: H155 for ≤10 m runs; H1000 or LMR-400 for 10-30 m. H1000 halves loss versus RG-58 (0.4 dB/m) at 150 MHz [Belden, 2023].
5. Can I mount a 40 cm Nagoya handheld antenna on a mast?
Technically yes, but range gains are minor. A 40 cm whip offers ≈ 2 dBi gain; mast height helps, yet full-size elements out-perform by 3–6 dB [Elektroda, adversus, post #17256983] Plastic housings also weather-crack outdoors after 1-2 years [ARRL Lab, 2021].
6. What connectors do I need to mate GP-3E to UV-5R?
Crimp SO-239 (female UHF/UC-1) on the antenna end and an SMA-male or SMA-female-reverse adaptor on the radio end, because UV-5R uses SMA-F [Elektroda, gumisie, post #17258885]
7. Could a high-gain antenna overload the UV-5R front end?
Yes. Strong nearby transmitters can desensitise or "clog" the UV-5R when using gain >5 dBi [Elektroda, c2h5oh, post #17257811] Keep the squelch tight and avoid mounting within 200 m of high-power masts.
8. Is a DIY J-pole worth building instead?
A well-made copper-pipe J-pole costs ~90 PLN in parts and often beats the GP-3E by 1–2 dB on VHF [Elektroda, adversus, post #17258793] Budget fits, but requires soldering and SWR tuning.
9. How do I tune a quarter-wave whip quickly?
- Calculate element: 300 / f(MHz) / 4 × 0.95.
- Cut stainless rod slightly longer; file down 1 mm at a time.
- Check SWR; stop when SWR < 1.5:1 across 148-150 MHz.
"You can shorten, not extend," warns an experienced builder [Elektroda, adversus, post #17257196]
10. What if local services use digital or encrypted modes?
Analog-only UV-5R cannot decode DMR or encrypted P-25. You will hear bursts or silence despite a good antenna. Edge case: some Polish PSP channels switched to digital post-2020 [UKE, 2021].
11. Can UV-5R receive ISS or NOAA weather satellites with these antennas?
Yes. The tape-measure Yagi linked in the thread tracks ISS packet and NOAA APT with strong signals [Elektroda, Radiokiller, post #17255950] Expect 3–5 minute windows per pass; memory channels help.
12. Is it legal to transmit on these antennas without a licence?
No. Polish law limits unlicensed VHF to specific bands (e.g., PMR446 at max 0.5 W). UV-5R exceeds that and requires an amateur licence for transmission [UKE, 2023]. Listening remains legal.
13. Cheapest antenna upgrade under 100 PLN?
A 1.6 m mobile whip like the Diamond NR-770H costs ~95 PLN, provides 2.15 dBi gain, and adapts to mast use with a bracket [Elektroda, adversus, post #17256983]
