RST Scope vs RF Calc JP
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
RST Scope
This utility app provides spectrum scope and waterfall displays for amateur radio operators. It enhances radios lacking these features by analyzing microphone input, allowing for clear distinction of Morse code and detailed audio frequency visualization.
- Spectrum scope and waterfall display
- Morse code distinction via FFT
- Adjustable waterfall speed
- Adjustable audio input level
- Switchable display band (wide/narrow)
- Display pause function
- Recording and playback of input sound
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This is an app for amateur radio operators with a narrow band of audio frequency, spectrum scope & waterfall display. You can get a rich display by microphone inputting the speaker output of a radio that does not have a spectrum scope or waterfall function. The FFT allows you to distinguish between the dot and dash of Morse code. [function] 1. Ability to change the speed of the waterfall 2. Ability to adjust the level of audio input 3. Function to switch the display band between wide and narrow 4. Display pause function (pause / cancel by touching the screen) 5. Function to switch the cross hatch ON / OFF by longTap 6. Frequency resolution is fixed at 40Hz. 7. Function to switch the USB/LSB by Left/Right Swipe 8.Recording/Playback function of Input Sound RST Scope(Free) https://www.youtube.com/watch?v=1s9RvOFp52g
RF Calc JP
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RF Calc JP is a practical calculator for amateur radio and RF work, for iPhone and iPad. Its signature feature: apply gains and losses (dB) to an absolute power value (W, mW, dBm …) in sequence — follow a signal from the transmitter through cable loss and amplifier gain to the final output, right on the keypad. KEY FEATURE: MIX ABSOLUTE VALUES WITH dB Enter "1 W − 3.8 dB" and it instantly shows 26.2 dBm (= 0.4169 W = 416.9 mW). Working with absolute values (W/dBm) and relative values (dB) in a single line matches how you actually reason about a link. FEATURES • Power / dBm: convert among W / mW / µW / nW / dBm / dBW. Enter one value and see the rest at once (e.g., 1 W = 1000 mW = 30 dBm = 0 dBW). • RF Chain: start from an absolute power, then stack each stage's gain (+dB) or loss (−dB): TX output → cable loss → amplifier gain → final output. See every stage and name each one. • Voltage: convert among V / mV / µV / nV and dBV / dBmV / dBµV. Set an impedance (default 50 Ω; 75/600 Ω or custom) to convert to power/dBm. Choose RMS / Peak / Peak-to-Peak as the reference. • Unit Converter: convert power and voltage units together, showing multiple units at once. • dB Converter: convert between dB and power/voltage ratios (e.g., +3 dB → power ratio ≈1.9953 / voltage ratio ≈1.4125). • VSWR: convert among VSWR, reflection coefficient |Γ|, return loss, reflected power (%), and mismatch loss. • Power Efficiency: transmitter efficiency from DC voltage, current and RF output (e.g., 13.8 V × 20 A with 100 W RF → about 36.2%). Reverse modes give the required DC current or the expected RF output. BUILT RIGHT • All internal math is double precision and is never rounded mid-calculation — rounding happens only for display, so chained calculations stay accurate. • Results appear in several related units at once. Set the number of digits and engineering (SI-prefix) notation in Settings. • Save a calculation history on device to review later. • Each calculator keeps its input when you switch. Attenuator (ATT) correction and large text sizes (Dynamic Type) are supported. WHO IT'S FOR • Anyone building a quick link budget from the rig to the antenna • Moving between voltage and power (dBm) • Converting VSWR and return loss without mental math • RF and electronics work that lives in dB and gain PRIVACY RF Calc JP collects no personal data and does no tracking. It runs fully offline with no account. Your calculation history is stored only on your device. SUBSCRIPTION All features are available via an auto-renewing subscription (¥200/year in Japan; equivalent local pricing elsewhere), with a 7-day free trial. Cancel at least 24 hours before the trial ends to avoid charges. Manage or cancel anytime in Settings > Apple ID > Subscriptions. A simple, accurate RF calculator for everyday operating and design. Feedback is welcome. 73! ■ Terms & Privacy Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://jpanhamlogapp.github.io/rfcalcjp/privacy.html
Screenshots
Verdict
The clearest difference is in-app purchases: RST Scope at none against RF Calc JP's 1. RST Scope also leads on update cadence (every 3 days vs every 6 days) and iOS requirement (15.6 vs 26.0). RF Calc JP's advantage is ads (none vs shown). On price and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. RF Calc JP sells 1 in-app purchase, starting at $0.99 per year. RST Scope asks for nothing beyond the download.
RST Scope ships an update every 3 days, RF Calc JP every 6 days. The most recent releases landed on November 3, 2026 and October 31, 2026 respectively.
| Parameter | RST Scope | RF Calc JP |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 3 days — better | Every 6 days |
| Ads | Yes | No — better |
| In-app purchases | No — better | Yes |
| Monetization | Ad-supported | — |
| Devices | iPhone, iPod | iPhone, iPad |
| Requires iOS | 15.6 — better | 26.0 |
| Further details — not scored | ||
| Size | 5 MB | 4 MB |
| Age rating | 4+ | 4+ |
| Developer | koji kamogawa | Hashimoto Yoshikazu |
In-app purchases
RST Scope
No in-app purchases
RF Calc JP
- RF Calc JP Pro (Yearly)7 Days trial$0.991 Year









