What’s Different Between different Nooelec versions of the RTL-SDR device?
There are quite a few different Nooelec RTL-SDR dongle versions, and the differences mostly come down to tuner chip, frequency range, stability / oscillator, size, and extra features like bias-tee. Here’s a breakdown + comparison, plus some example models.
What’s Different Between Nooelec RTL-SDR Versions
Here are the key factors that vary, and how different Nooelec models compare.
- Tuner Chip
- Many Nooelec SDRs use the R820T2 tuner.
- Some “extended range” models use the E4000 tuner (e.g., SMArt XTR).
- Why it matters: E4000 gives you a higher max frequency, but has trade-offs (see point below).
- Frequency Range
- R820T2-based models: ~25 MHz up to ~1.75 GHz (depending on model).
- E4000-based “XTR” models: extended tuning, but also a gap in their tuning around ~1.1–1.2 GHz.
- According to measurements, the E4000 is more sensitive in some lower-to-mid bands (e.g. < 450 MHz), but less so at higher frequencies (~1 GHz), compared with R820.
- Oscillator / Stability (TCXO)
- Some versions (SMArt series) have a 0.5 ppm TCXO (very stable reference).
- This helps reduce frequency drift, which is especially useful for narrow-band or HF work.
- Bias-T (Power on Antenna Port)
- Models with “Tee” in the name (e.g., SMArTee) provide an always-on bias-tee.
- This is useful if you want to power active antennas or LNAs over the coax.
- Size / Enclosure / Heat
- Nano Series (e.g. Nano 2, Nano 3) are very small: good for embedded or mobile setups.
- The Nano 3 has an aluminium case; some earlier Nano models had plastic.
- Smaller size means less heat dissipation, which can affect performance/noise.
- Direct Sampling / Low-Frequency (HF)
- Some SMArt models support direct sampling via “Q-branch” to receive very low frequencies (e.g., down to ~100 kHz).
- That said, for true HF performance many people still use an upconverter.
- Current Draw / Power Consumption
- Some “Tiny” versions (e.g., XTR Tiny) draw less power, making them more suitable for portable or battery-powered systems.
- Models with bias-tee need to manage power carefully when powering external devices.
Example Models & What Makes Them Different
Here are some representative Nooelec dongles, with their trade-offs:
- : R820T2, stable TCXO, wide tuning, good all-rounder.
- : Same tuner and stability as SMArt, plus a bias-tee to power LNAs.
- : Uses E4000 tuner, extended frequency range (above what R820T2 covers), but more limited in some bands (due to E4000 gap).
- : Compact form, R820T2 tuner, MCX connector, decent performance for its size.
- : As Mini 2 but with 0.5 ppm TCXO for better frequency stability.
- : Smallest Nooelec SDR, R820T2, plastic enclosure (later versions improved over heat).
When to Choose Which Version
- If you care about ADS-B or VHF/UHF: A standard R820T2-based SMArt or Mini is great because of sensitivity and clean tuning.
- If you want to power an LNA from the dongle: Use a “Tee” version (SMArTee).
- If you’re interested in very high frequencies (e.g. >1.8 GHz): Consider the XTR (E4000) models — but be aware of the tuning “gap” around ~1.1–1.2 GHz.
- If you’re building a portable or embedded setup: Go for Nano or Mini, balancing size vs performance.
- If frequency stability matters (e.g. narrowband, decoding weak signals): Use a model with the TCXO.
Trade-Offs to Be Aware Of
- E4000 vs R820T2 is not a one-size-fits-all: E4000 may be more sensitive in some bands, but more prone to “birdies” (spurious signals) and less clean at others.
- Bias-tee → noise: Adding a bias-tee can introduce noise, so the design quality matters; Nooelec’s SMArTee v2 tries to minimise that.
- Small form factor = heat risks: Tiny dongles run warmer, which can affect performance or drift.
- Direct sampling is limited: While you can get down to ~100 kHz with some models, it’s not the same as a proper HF front-end or upconverter.
My Recommendation (Given Your Interests)
Since you’re an amateur radio astronomer:
- If you want versatility across many bands, a SMArt V4/V5 is probably the safest bet.
- If you’re planning to run low-noise amplifiers (e.g. for weak signals), consider a SMArTee so you can power the LNA directly.
- If your interest includes higher bands or satellite work, the XTR might be worth it — but check that the tuning gap doesn’t disrupt your target signals.