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Last modified 2023-07-07

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National HRO-500

A picture of National HRO-500

SPECIFICATIONS

GENERAL
Type:VLF/HF receiver
Frequency range: 0.005-30 MHz (Sixty 500 KHz bands)
Tuning steps:Analog / continuous
Frequency stability:? ppm
Mode:AM / SSB / CW / FSK
Channels / memory management: None
Power supply:Mains: 115 / 230 VAC
or 11-16 VDC
Current drain / power consumption:Max 200 mA @ 12 VDC + 590 mA for the pilot lamps
Antenna impedance / connector:50 ohm / SO-239
Hi-Z / ?
Dimensions (W*H*D):419*194*324 mm (16.5*7.62*12.75")
Weight:14.51 Kg (32 lb)
Other features:




RECEIVER SECTION
Receiver system: Single conversion superheterodyne (Below 4 MHz)
IF: 230 KHz
Double conversion superheterodyne (Above 4 MHz)
1st IF: 2.75-3.25 MHz
2nd IF: 230 KHz
Sensitivity: 0.5-30 MHz:
AM: <2 uV (10 dB S/N)
SSB/CW: <1 uV (10 dB S/N)
0.005-0.5 MHz:
25-200 uV (10 dB S/N)
Selectivity: Selectable
8, 5, 2.5 KHz and 500 Hz (-6 dB)
Image rejection:0.5-30 MHz: 80 dB average, 50 dB minimum
AF output power / speaker: Early version: 1 W at 4.4% distortion / No internal speaker
Later version: 1 W at 4.4% distortion / 3.2 ohm
External speaker connector:3.2 ohm




MISCELLANEOUS
Manufactured:USA, 1964-1972 (Discontinued)
Additional info: National's first solid state receiver

New price 1965 in the US: $1295 (Without options)
Related documents: User manual (3 MB)
Schematic diagram (356 KB)
Modifications and fixes:
Reviews: 73 Magazine: August 1965, page 80
CQ: November 1965, page 51
Monitoring Times: March 1985, page 17
Popular Electronics: August 1965, page 45
Options / Accessories:
HRO-500TS
LF-10
RMK-5
Matching speaker
LF preselector
Rack kit
A rear inside picture of National HRO-500