10 GHz SIEMENS Traveling Wave Tube Amplifiers 300 / 600 W for ham use

These amps were operated for satellite FM-TV uplink operations in the 14-14,5 GHz

band. The system is divided into an 19" amp drawer and a power supply drawer.

1. The amplifier drawer :

The amp is equipped with a Siemens YH1422 air cooled TWT capable of 300W in a

continuous service with maximum power of 350W ( supplier data ) .The TWT works strictly linear, usable for any modes common in ham practice and is modified for operation between 10.0 and 10,5 GHz. No limit for "key down " times at full output power

The TWT is in a 19" box 31cm high and 70cm deep. Drive power is 50mW to max 2W

into the SMA input. Input connector is followed by circulator, 0-20dB variable attenuator,

directional coupler for input power monitoring and fed through a circulator into the

TWT. So perfect input matching is provided under any circumstances. Output of the tube is

a R120 / WR75 waveguide, passing a triple coupler and ending at the output flange.

There are 2 different models with output flange on front or on rear panel available.

Two of the directional couplers are for measuring forward and reflected power by a

SMA diode detector. The 3rd coupler is for measuring purpose like a spectrum monitor

and is fed to a front panel N-connector.

The original thermistor power sensor was removed, because not useful at SSB or CW and

replaced by a peak power meter with a four quadrant multiplier to reach linear peak power

indication on the original instrument. There are pushbuttons for input, forward and reflected

power indication on the front panel (analog ) meter

Cooling air leaves the box on rear panel with a ring to connect a hose to get away warm air

if required. All high voltage parts are isolated and cannot be touched in the TWT box.

High Voltage cable to the PSU box is approx. 2m long with an AMP HV connector.

Manual available here: Leistungsverstärker 14 GHz S42023-H82-A17

2. The power supply box

The PSU box is also 19" size, but 35cm high with 80cm depth. It is operated from single phase 230V AC and can be switched to 115V AC also. ( at double input current ! )

There are screwed bridges for changing between 115 / 230V line operation.

The PSU consists of several independent switching mode supplies, driven and synchronized by common 40KHz xtal clock.

Collector, helix and grid supply are independent from each other adjustable by 10turn pots located behind a service panel in PSU front.

These wide range adjustment capability allows operation with nearly all single collector TWTs up to 350mA collector current and a helix supply up to 12KV at 15 mA. Voltages and currents are displayed on 4 red LED meters and can be adjusted in standby mode by the front panel service switch without running the TWT in "hot" mode

All control circuitry is on 2 big pcbs and made in conventional techniques with CD4000 series

CMOS and wired components. No µPC, no SMD . All PCBs are pluggable and easy to remove for maintenance or cleaning from dust after long operating periods. No high voltage

components are sealed , so easy to service for the price of requiring space between each other.

Complete schematics and PCB drawings are supplied, but a very detailed description of

entire circuitry is available in German language only ( Siemens product ! )

There are multiple protection circuits in the system, because it was designed for remote

operation. Not all of them seem to be needed for ham operations. Protections are against:

- All TWT voltages and the utility line are permanently watched for over- and undervoltage.

- Overcurrents in TWT, possible Helixtrips with 3 automated attempts for restart

- Undercurrent in TWT heather line ( nice with homemade long cables or bad connectors! )

- Overtemperature in PSU box or TWT collector in case of insufficient / blocked cooling air.

- Warning / power down if covers are opened was removed for ham use.

- Blower pressure at TWT , maybe useful at remote operations.

- Too high / low rf output warning is removed, not usable for SSB + CW operating mode .

- SWR warning and shut down after 3reaset attempts was removed for ham use .

There are 4mm connectors for testing heather voltage and current as well as collector

voltage at ground-level with normal multimeter isolated from high voltage circuitry.

Heather current is reduced in standby mode to protect cathode in long standby periods

and is automatically switched to full value at ON-status / XMT .

The amp is constructed for permanent transmitting, but can be given an easy and fast PTT

by the grid-relay. That means complete cutoff of cathode current in stby, but full power in

200 mS after operating PTT ( no QSK! ) This HV- relay coil operates at 24V level against ground potential. No rf noise is generated in stby at rf output, no power dissipation in the TWT.

All front panel pushbuttons , status and warning lamps are opto-isolated reachable from

rear panel connector for remote operation. For output power indication is an analog

current available for a remote meter .

3. The 600W amp

Same sizes and outlines, but a YH1421 with max. 750W out in continuous class service.

The TWT blower is operated with 3 phases. The output directional coupler has slightly

different coupling factors, but operations and indications are similar.

The PSU can be operated at 115/230V, has more electrolytic capacitors and a bigger

collector switch mode converter with 16 power FETs in a full wave bridge circuit.

Heather, grid and helix supply and external connectors are identical with 300W amp.

4. TWTA for 6cm ham band : Actually we have one ready for use TWT for 6cm

band with identical data to the 10GHz model, but of course with different TWT and waveguide output size.

4. Some general notes

There are 2 big capacitor filters in the AC supply line, that may irritate some sensible

magnetic fuses or fault-current-switches at power-up. In that case we recommend to

remove them and install an external filter with less capacity to ground.

External fast PTT can be done by simply laying your ground-free external PTT contact

in series with the front panel operate/service switch.

5. Some ideas for EME

If you want no losses by long waveguides, you can take the TWT and blower out of the

box and install it directly at the antenna feeder or nearby. High voltage cables can

be made of RG213 ( up to 25KV ) between PSU and the TWT. With very long cables the heather voltage must be readjusted for the voltage loss - easy done on PSU front panel. I use 55m cable between PSU and TWTs on the tower already 10 years without trouble.

The TWT is sealed, so high voltage is no problem, but the PSU is constructed internally

open. That is nice for service, but for indoor use only - or in a clean dry housing with some

preheathing capability for cold and moist days / nights, otherwise there might be arcing

on the HV converter PCBs if the get humid !

A good waveguide relay is mandatory, and do not forget a feedback from the WG switch

final tx position to your sequencer - otherwise the preamp is killed in milliseconds.

6. Some important precautions :

The output power exceeds that of most microwave ovens, so precautions must be taken

to prevent humans or animals entering the area in front of the antenna while transmitting,

especially at low antenna elevations !!

Do not operate the PSU without top cover when transmitting. It is not only dangerous

because lethal voltage inside - the cooling air must flow from front panel through the entire box, otherwise the collector supply may switch off at 80 deg C at the transistor cooler block.

with PSU overtemperature alert on PSU frontpanel LED

This is absolutely not dangerous, but happens only at the "new ODX - QSO" !

7. Price and delivery :

The 300W TWTA 10 GHz : 1500,- € plus shipping

The 600W TWTA 6GHz or 10 GHz : 2000,- € plus shipping

Single Power Supply for TWTs up to 350W out:400,- € plus shipping

We offer a ready-for-use amp with power supply. The amp is modified for ham use

at 10.0 to 10.5 GHz. It is an amplifier without an antenna switch. Input is SMA and

output is WR75 / R120 waveguide. Line input at PSU has no pluggable connector and

is for supplied for fixed utility cable installation. High voltage cable and special flat

ribbon cable between amp and PSU is supplied. There are no cables or boxes for remote operation available, but detailed schematics for remote operation interface are supplied.

A complete set of schematics and PCB drawings is supplied with the amps. Additional

description of circuitry and installation / operation in German language available on copy costs.

Amps can be inspected and tested at DL0SHF in Rönne near Kiel in northern Germany.

Have a look at our TWTA operated site at DL0SHF at : http://sat-sh.lernnetz.de

Price is without shipping to your destination. Shipping will be preferably on a standard pallet to prevent any damage by rough handling with a standard parcel. For European customers we might find an arrangement for different way of shipping / delivery, please ask.

Customers outside Europe please check for local custom fees and State taxes. We offer

shipping to your border / customs only. You must pay any additional local duties that

may be requested by your local state authorities.

If any further questions, do not hesitate to ask, preferably by email per@per-dudek.de !