UHF Netzwerk Service
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Informations about: Hydra, the 10 Ghz Frontend
Update Mar 14, 2021

DUBUS 3/2020 was released in Sept. 2020.,

(To subscribe to DUBUS, the bilingual magazine for the serious VHF and up operator,
click here: www.dubus.org)

....on this page you will find news, bonus material, FAQ and more...

What is Hydra?

"A 10 Ghz Extension for Adalm-Pluto(tm)"
Hydra is a minimal 3cm band frontend, enables you to use FM/CWalso on 10Ghz.
The size of the PCB is made to fit on the ADALM PLUTO (tm by Analog Devices)
which is also called PlutoSDR. Hydra originated from one development for
El Cuatro, the multiband UHF/SHF receiver, see link below.

Overview: Hydra V4....V7 (FM/CW)"

Hydra for QRP
with Antenna Switch

Hydra for QRO
without Antenna Switch

Use your own coaxial antenna relay
with your PA and LNA.

Hydra V4r (15-20mW)

Hydra V4r
(2 pcs available)
ADRF5019 antenna switch
NLB-310 amplifier
on Rogers4003C laminate
€ 99.- EUR (**)

Hydra V5 (12mW)

Hydra V5
(currently not available)
PCB shown, no current photo available
No antenna switch, but seperate
NLB-310 amplifier
SMA female connector for 3cm RX
and 3cm TX: € 99.- EUR (**)

Hydra V6 (30mW)

Hydra V6
(currently not available)
ADRF5019 antenna switch
and HMC451 amplifier
€ 149.- EUR (**)

Hydra V7 (60-80mW)

Hydra V7
(2 pcs available)
No antenna switch, but seperate
SMA female connector for 3cm RX
and 3cm TX: € 149.- EUR (**)

Harmonic Hydra HH2, HH3 (DATV/SSB)"

The story: Colin, G4EML who is the maintainer of the Langstone project (1)
investigated a feature of the Pluto, that had previously been discussed on the
British Amateur Television Group forum, that the harmonics of the Pluto are useable
and are modulated 1:1 as the fundamental.

This is not simply the Pluto modulating the carrier and then producing harmonics of
the result but appears that the harmonics of the carrier are being produced internally
and then those harmonics are being modulated. It was found that this effect was most
effective with the 5th Harmonic. The same SSB signal that is purposefully modulated
onto the carrier at 2073,600 MHz is therefore also perfectly readable at the fifth
harmonic 10368MHz at a level of abt. -30dbm (3).
Read the full article in DUBUS 2/2021, which will be published in March 2021.

For more information about DUBUS click here: www.dubus.org)
Langstone Project is here: https://wiki.microwavers.org.uk/Langstone_Project
To recover this 5th harmonic, the "Harmonic Hydra" was build, currently HH2 and HH3 is available:

Harmonic Hydra
HH2 (2mW)

2 pcs available
Hydra HH2
Needs ext. amplifier (shielded)
No antenna switch, but two seperate
SMA female connectors for 3cm RX
and 3cm TX: € 99.- EUR (**)

Harmonic Hydra
HH3 (2mW)

soon available, stay tuned...
Hydra HH3
Photo not yet available
Needs ext. amplifier (shielded)
No antenna switch, but two seperate
SMA female connectors for 3cm RX
and 3cm TX: € 129.- EUR (**)

Different Hydra versions:

All versions have the following in common:
LNB for receiving, controls for +5V TX and +5V RX.
2 SMA male connectors fit on the ADALM-PLUTO, distance of the plugs (center to center)
is about 23.5mm. The 2nd SMA plug needs to be mated with your PlutoSDR, because the
distance of 23.5mm differs a small bit.
All versions work with SDRs from Analog Devices (e.g. Pluto), fits onto SMA connectors.
V3 and V6 were also tested on Ettus SDRs. Need extra cables to connect.
HackRF one (with only one antenna connector for RX and TX) needs Hydra V0 (2-3mW) which
has pin-diode switch on the input. Available on request.

There are differences in the kind of 3cm signal creation, and there are models with
and without antenna switch.

Prelimary Specifications:

TX Power: V4:10mW V4r:15mW V5:12mW V6:30mW V7:60mW
Fundamental feedthrough (5.184GHz input to 10.368Ghz out): -40dbc
RX noise Figure: V2: 10-13db NF, V3, V4: 10db NF
RX frequency tolerance: 0.2ppm
Supply Voltage: 5V (+0 -0.5V)
Supply Current TX: up to 200mA (V6,V7: 300mA)
Supply Current RX: up to 75mA

Frequently Asked Questions - FAQ

(please send mail for the Q&A, all answers will be available here.)

What is the price including shipping?

Hydra V4r: € 99.-
Hydra V7: € 149.-
Reduced rates for tracked shipping: € 10.- to EU/UK, to US/VK/JA is € 15.-
Other countries € 15.- or € 20.-
Paypal is preferred. All prices are in EUR, include 20% VAT and are valid
from Jan. 18, 2021.
Availability depends: V4r and V7 are ready for shipping (Mar 14,2021).
Other models are available again from May 2021.

How can I order?

Please send email (address see below) to me, including your shipping address. I will
contact you once i am ready to send the PCBs out.

What software do you use in general for Pluto?

Currently I do only the hardware, but my friends use SDRAngel, SDR-Console,
GNU-Radio and the Langstone project software. Once I have tried every possibility
myself in software, I will report here.
For now it seems that the Langstone software, with Raspberry Pi4 and 7" display is the
best for QSOs, but for testing purposes other solutions may be preferred.


-Amateur radio
-Portable testing equipment
-Microwave portable equipment

Other Published Articles:

Information about the El Cuatro FM/CW Microwave Multiband Handheld Transceiver, published
in DUBUS 3/2018 is here

Updates to the Hydra Article, published in DUBUS 3/2020:

The following clarifications to the schematic are found:
- on the +5V TX Line, the 100pF Capacitor should be very close to XX1002.
- both +5V TX and +5V RX line need a 2k2 or 3k3 resistor to ground to ensure switching
voltages at the specified range, for "low" 0-0,2V is specified.

Hydra V1 description:

Included here for illustration, was described in DUBUS 3/2020. No longer available.
is a extension for the ADALM-PLUTO (tm by Analog Devices) learning Module, and enables
the use of the 10Ghz Band (10368-10370, 10400-10450) and beyond. From a former project
"Hydra V0" was reused. For a detailed description, PCB layout and schematic see
DUBUS 3/2020.
X-Band (10Ghz) frontend for PlutoSDR

Pluto must be set to (e.g.) 5184Mhz for TX and receiver must be set to (e.g.) 618Mhz.
Any more questions? Please email me and the answers will be added to the FAQ.

Typical Hydra package contents

Hydra V1 package contents
All versions of Hydra areis shipped in an antistatic bag, with one SMA plug not
mounted, this has to be fittet to your Adalm Pluto, as the distance between the SMA
connectors is slightly different. The cable on the top is for +5V, a manual RX/TX switch
is no longer mounted, but you can connect a relay (which is switched from USB
or Raspberry PI port). The board is tested for TX and RX performance, RX/TX
function and that the 25Mhz oscillator is continuously running. The TCXO for RX
is always on, regardless of RX/TX state to have more stable frequency.

Description of Hydra V4r, Hydra with Rogers 4003c.

Hydra V4r is the same as V4, but is build on Rogers 4003C material. Power output is
15-20mW. Electrically identical to the Hydra V4, but less loss.
new: Hydra V4r 10Ghz Extension

Description of Hydra V7, more power with HMC451 amplifier.

Hydra V7 is the same as V5, but HMC451 amplifier for about 60-80mW.
No antenna switch included.
new: Hydra V6 10Ghz Extension

Bonus material, which was not available
in time for DUBUS 3/2020

RX/TX switching:

is always done with the same footprint for +5V TX and +5V RX.
It can be done manually:
- with a miniature switch (e.g. Hartmann SX254)
- With a small SPDT switch (see photo)
Hhttps://www.youtube.com/watch?v=9869CcKULwoydra X-Band RX/TX switching
or automatic from your Raspberry, laptop or PC:
- With a mechanical SPDT relay, which can be a seperate USB relay
- or a relay driven from Raspberry Pi 3.3V Pin (like Langstone project).
- The relay then provides +5V RX and +5V TX seperately to the pads, see above.
So no extra +5V supply to the Hydra PCB and no manual switch is needed.

LNB LO Options:

The LNB in default configuration works with 9750 Mhz (25Mhz x 390). The LNB
features also a "high band", where the multiplicator is 424 which gives 10600 Mhz
LO (25Mhz x 424). You can remove the 25 Mhz Oszillator and feed your own frequency
as a reference frequency. I successfully used 24,1 to 25 Mhz, but 26 Mhz failed.
So you could adjust the receiving frequency also to 144 or 432 Mhz, if you want.
So for synchronous receiving with several RCVRs you only have to feed the LNBs with
the same phase of reference signal.
Hydra X-Band frontend LO mod

About the author:

Fred, OE8FNK, now also microwave manager in OE, is doing UHF/SHF amateur radio for a
lifetime. His background is microprocessors and software, but interest radio and radio
astronomy made him build electronics and RF. All equipment is made to enable
all radio amateurs to participate in UHF/SHF activities, and to create local
activity on microwaves bands (70cm-3cm)
, often within the local club or district.
This is often done with the absolute minimalistic equipment, and the least
possible TX output power, but encourages some to maintain their equipment and activity
on microwave bands.
We are making contacts over a distance of 60-100km monthly in activity contest,
with 0.0003 to 0.06 Watts now for many years on frequencies from 1-10Ghz. And now even
doing experiments on 24Ghz and 122Ghz over shorter distances. Results are
documented and available at http://mikrowelle.oevsv.at

Still reading? Any more questions? Appreciate your comments and feedback :-)


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