LNA QRO with built-in bypass relays for 6m 2m and 70cm bands

Update from 2020-01-28

VSWR Bypass
VSWR Bypass

The following changes have been made:
– Added power injector for power through the feeder. SWR (TX mode) not worse than 1.1 for 2m and 1.2 for 70cm;
– Added the function of switching the LNA input from the antenna to a load of 50 Ohm. Useful for checking the ratio of antenna noise to load noise. Switching is carried out by applying increased power to 16 V (briefly, for the duration of the measurement). The operating voltage of the LNA is 12 V. To prevent overheating of the LNA, do not leave 16 V for a long time!
– LNA 70cm QRO with SAW filter now, compensation inductances and power injector.


This LNAs are suitable when operational conditions requires huge RF power bypass. They are quite simple in installation – just connect the unit into the feeder.

Unlike our low-bypass solutions this lineup doesn’t contain RF VOX. For RX/TX switching you should use the sequencer, for example this one.

LNA 2m QRO schematics

LNA 2m QRO schematics revision from 2021-06-05
LNA 2m QRO schematics revision from 2021-06-05

 

LNA 2m QRO schematics archive

LNA 2m QRO schematics revision from 2018-05-12
LNA 2m QRO schematics revision from 2018-05-12
LNA 2m QRO schematics
LNA 2m QRO schematics

LNA 2m QRO layout

LNA 2m QRO layout revision from 2020-10-02
LNA 2m QRO layout revision from 2020-10-02

LNA 2m QRO layout archive

LNA 2m QRO layout revision from 2018-05-12
LNA 2m QRO layout revision from 2018-05-12
LNA 2m QRO layout
LNA 2m QRO layout

LNA 70cm QRO schematics

LNA 70cm QRO schematics revision from 2021-06-05
LNA 70cm QRO schematics revision from 2021-06-05

LNA 70cm QRO layout

LNA 70cm QRO layout revision from 2020-10-02
LNA 70cm QRO layout revision from 2020-10-02

LNA QRO AFC graphs below.

LNA-6m-QRO Amplitude-frequency response graph from 2016-11-15
LNA-6m-QRO Amplitude-frequency response graph from 2016-11-15
LNA-2m-QRO Amplitude-frequency response graph from 2016-11-11
LNA-2m-QRO Amplitude-frequency response graph from 2016-11-11
LNA-70cm-QRO Amplitude-frequency response graph from 2019-10-01
LNA-70cm-QRO Amplitude-frequency response graph from 2019-10-01

Conclusion

QRO series LNAs are allow to use PAs with high RF power without additional RF relays. Considering the fact that NF < 0.6dB is usually enought (for 2m band), LNA-2m-QRO is pretty universal solution. For 70cm NF < 0.8dB is OK for Tropo and Contest QSO. For 70cm EME QSO we still highly recommend to use our EME solutions for this band (based on SAV-541+ or ATF-531P8) with additional RF relays.

We had more than 30 working QRO units for 2m and 70cm bands when this article was created. However you should consider some protective measures – reducing the transmitter’s RF Power while this LNAs are used with antennas that have a bad VSWR (greater than 1.5).

Warning!
Working with antennas, that have a bad SWR (> 1.5) may lead to failure of the RF relays.

List of changes:
– instead of PGA103, ATF53189 used;
– LNA 70cm QRO switched to SAW filter design.

LNA 2m QRO N-female

LNA 2m QRO N-female

Specifications
Name LNA-2m-QRO-N-female
Based on ATF-53189
Pmax TX bypass 1000 Watt
Gain > 24 dB
NF < 0.4 dB at 144 MHz
OIP3 36 dBm
Filter BW (-3 dB) < 15 MHz
P input (max) 24 dBm
Supply operation 12 V & 300 mA
Impedance 50 Ohm
RF connectors N-female
Weight 0.25 kg
Package contains
1 x LNA-2m-QRO-N-female

LNA 70cm QRO SAW filter N-female

LNA 70cm QRO SAW filter N-female

Specifications
Name LNA-70cm-QRO-SAW-N-female
Based on ATF-53189
Pmax TX bypass 800 Watt
Gain > 20 dB
NF < 0.4 dB at 432 MHz
OIP3 36 dBm
Filter BW (-3 dB) < 20 MHz
P input (max) 24 dBm
Supply operation 13.8 V & 300 mA
Impedance 50 Ohm
RF connectors N-female
Weight 0.25 kg
Package contains
1 x LNA-70cm-QRO-SAW-N-female

General inquiries: e-mail logo sales@vhfdesign.com
Technical support: e-mail logo us4ici@vhfdesign.com

Check the stock availability – here
Request for an assembly – submit this form

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