Ten Tec Titan II 
Biggie from Ten Tec
by Bob Hutchinson, N5CNN

Is this really 1000 X over my first Ten Tec? It sure looks that way at first glance. What I mean is - some many years back my first transceiver was the classic Ten Tec Argonaut 409. After passing the General, my first sideband contact was made several hundred miles away with 2 1/2 watts on 40 meters powered with a small Die Hard battery. What excitement that was. Stayed up all night talking on 40, 15 and 10 meters on my 40M dipole antenna. It appears this Ten Tec has a 1000 X advantage over my first one. Of course, I later bought the companion Ten Tec 405, 100 watt linear amplifier and thought I was a power broker with it's wonderful 50 watts into the coax.

After we look really close inside, we will take this Ten Tec Biggie to the WIA bench and run it through our standard operational review.

About the box -
Ten Tec has the equipment for making big foam-in-place end caps for the amplifier for superb protection from the rigors of shipping. No shortcomings in the shipping arena. The amplifier came properly seated in the box upside down so it ends up right side up when the box is flipped onto the table or bench.

Some disassembly - assembly required?
For convenience, the amplifier has only a few screws holding the top cover on. The balance of screws are in the accompanying plastic bag containing extra fuses and transformer screws. I removed the cover and set it aside so we could continue with the assembly, but there is none at this point. The Biggie tube is already installed and the transformer will wait.

Ten Tec has been in the enclosure and cabinet making business probably since the beginning and their experience shows with this product. Everything appears to well though out and engineered.

OK, it's tent duty
The amplifier is nice and light without the plate transformer so I set it inside the light tent onto the caster equipped roll around plant stand. I always like this part, working the Olympus digital and the lights. I try to share everything inside with browsers.

RF section
Lotsa space, nothing cramped or cluttered. First quality components. Why, they could put several tubes in this compartment. Robust Load and Tune air variable capacitors are driven with smooth 6:1 ball vernier drives. The band switch is a longer component than found in most amplifiers. The coils are not cramped or too close. Everything has plenty of room here. The long band switch places the wafers in good position where they need to be so short leads can be utilized. The entire switch is well supported by the many soldered connections to components. If there is plenty of room in a case this is a good way to utilize it.

Cooling - Centrifugal squirrel cage type blower
Unusual mounting of the cooling blower for a Ham Radio amplifier. Most makers mount the blower inside where it pulls air in, over and around other components in the box and into the blower inlet. Then it is forced into into the pressurized plenum and through the radial/axial heat exchanger surrounding each tube and out of the box.

Ten Tec cools this amplifier with a different system. Fresh cool air enters the blower from under the amplifier and is forced into the pressurized plenum chamber and up through the axial/radial heat exchanger of the Biggie Svetlana 4CX1600B ceramic/metal tetrode. There is a bail under the front that can be flipped down to raise the front of the amplifier to a better viewing angle. The manual says the underside cooling air entrance will get plenty of air with the bail in either position.

 The large plenum chamber houses circuit boards, AC mains, soft start, metering, control circuits, etc. The top amplifier cover is well ventilated over the RF and power supply sections with plenty of holes and slots for convection cooling. None of this heat influences the tube cooling. In tube type linear amplifier operation, the great majority of the total heat generated is from the tubes. Heat not generated by the tubes is not significant at high power output levels.

Most circuits in the breeze
I removed one side and the bottom cover to expose the bottom of the amplifier which is also the cooling air plenum. Reason the top side RF and power supply sections are so uncluttered is here, where everything else is. Except for the rectifier/filter, all the circuit boards are here, in the breeze box. Mains start and in-rush or soft start circuitry is here along with screen, grid, bias, QSK, SWR and ALC control circuit boards.

It appears that input impedance matching resistor networks are used for the tetrode tube. Tuned input circuits are not necessary. The input board is standard with input filter circuit that rolls-off input of frequencies above 15 meters. An optional replacement input board for us so called legal, yammer, yammer, yammer folks rolls-off frequencies above 10 meters. However, there is no mobile mounting bracket included with the Titan II and it will not operate on 12 VDC without a VERY HIGH capacity DC to AC inverter, also not included.

Noise?
Well yes, it seems the centrifugal blowers required by these indirectly heated tubes, with radial/axial heat exchangers, have to turn fast and they often make noise at a frequency that is irritating to humans. The amplifier maker provides the cooling necessary for the demands of the demanding.

QSK circuit
Ten Tec perfected reliable QSK circuits years ago and the feature is a specialty of theirs. As far as I know all their amplifiers have or have had fast T/R circuits capable of full break-in CW. Of course, this type of circuitry usually results in smooth VOX operation with little noise.

The Rusky Svetlana 4CX1600B tube
Ok, here are some snippets about the tube. It could all be folklore.

• The 4CX1600B tetrode tube is not a military tube and was produced just for the Ham Radio amplifier market in the U.S.
• It is a 2,500 watt dissipation military tube disguised as a 1,600 watt dissipation tube so an amplifier utilizing this Biggie could be FCC type accepted.
• It is considerably more power capable than two 4CX800A type Rusky tetrodes.
• Replacements are readily available at inexpensive prices.
• This tetrode, similar to the 4CX800A/GU74B tube, requires some simple impedance matching but no tuned input circuits.
• It is just loafing in legal ++ Ham Radio amplifiers and is capable of much more power output with a healthier plate transformer.

The manual
Ten Tec has always provided well done manuals. This one continues with that tradition.

And the power supplies?
With 240 VAC mains the large single purpose transformer provides about 2,050 VAC to the bridge rectifier's 20 6 A., 1,000 PIV, 6A10 type Biggie rectifier diodes. Filtering is handled by nine high quality Mallory computer grade electrolytic capacitors. B+ production is 3,000 to 3,150 VDC B+ with no load. Everything is open and easy to get to if service is every needed. Note the short length of the Mallory caps.

Ancillary power for tube cathode heater, metering, screen, bias, QSK circuits, etc., is provided by a multi voltage transformer.

One of the big meters is dedicated to plate current and the other is switched to read high voltage, screen grid current, forward power or reflected power. There is also a horizontal green LED bar type power meter with the red 1,500 watt red LED at the right end of the bar. This is similar to the bar display on the original Titan.

The band switch has two position for 16OM and two positions for 40M. The 40B position is for the 30 meter band. The 15M position is used for 17M operation and and 10M used for 12M operation.

Protective circuits - can ya break it?
A plate current protection circuit will shut down the amplifier if current exceeds 1.5 A. The standby switch indicator lamp will go out, indicating shut-down. The switch is cycled to reactivate amplifier. Screen grid current absolute maximum is 55ma, which you should never see on the screen grid meter as 5ma to 20ma is normal current. Screen grid current and control grid current red LEDs overdrive indicators should never come on. I never noticed even a blink during this review and screen grid current never exceeded 20ma.

Bench
Our test bench is equipped with a 2000 watt fan cooled dummy load and a 3,500 watt low pass filter. For output power measurement, Bird 43 and Coaxial Dynamics watt meters are utilized, cabled in series. We normally have 2,500 watt slugs in both meters but for higher power amplifiers we sometimes use 5,000 watt slugs. The bench has a superb 10,000 watt antenna switch utilizing Jennings vacuum relays, designed and built by this writer, for access to 75M & 40M dipoles, 20M, 17M and 15M verticals and the dummy load. A  putt-putt wattmeter is used between exciter and amplifier to measure drive power and SWR.

For high voltage readings we utilize digital voltmeters and 6KV and 40KV Fluke high voltage probes. We average readings with two setups to assure no surprises with accuracy.

Accuracy of measurement
For this project both wattmeters are equipment with 2,500 watt slugs. We record the average of the two wattmeter readings.  Both Bird and Coaxial Dynamics spec. an available inaccuracy of + or - 5% of slug rating at a mid-scale reading. This works out to be an error factor of + or - 125 watts at mid-scale with 2,500 watt slugs. Utilizing two instruments gives an assurance of accuracy if both give the same or similar readings. The maker's don't mention accuracy at close to full meter right deflection, but we assume less.

Will this fine box perform? Does it run?
I went through my systematic load test for the following bands on the dummy load. Drive signal is CW.

Data below is grouped:
Screen grid Current MA / Plate Current MA / CW Power Out Watts

Band	QRP Settings Column 50W. Drive Screen Grid/Plate/Power	Medium Drive Column 70W. Drive Screen Grid/Plate/Power	Max. Drive Column 100W. Drive Screen Grid/Plate/Power
1.90 Mhz	5/800/1,100W	7/1000/1,300W	7/1300/1,850W
3.90  Mhz	7/700/1,250W	7/850/1,475W	10/1200/1,900W
7.200 Mhz	5/750/1,250W	9/900/1,600W	12/1250/2,050W
14.225 Mhz	15/650/1,300W	12/1000/1,750W	13/1250/2,100W
18.140 Mhz	19/750/1,300W	20/900/1,850W	20/1100/1,950W
21.350Mhz	15/800/1,600W	16/1100/1,900W	18/1250/2,150W
	Ten meters not enabled on this amplifier yet.

Over drive column on the right

The indicated B+ is 2,900 VDC with no load and 2,700 VDC under load at legal limit. The measured B+ is 3,000 no load and 2,600 under load.

During the testing we did not received a single overdrive indication from the red LCD screen grid or grid overdrive lamps. The plate current protection circuit trips and shuts down the amplifier when 1.5 amps is exceeded. It tripped once and was reset by cycling the standby switch. Tuning was straight forward, easy to manage and repeatable. The Titan II controls on the right side of the box are easy and comfortable when the amp is residing on the left side of the station. The fast T/R circuit in this nice QSK capable amplifier could not be heard during testing.

Conclusion
The Titan II is produced with the highest quality components and the case and layout are superb. Cooling is more than adequate for the most demanding Amateur service. It will deliver legal limit plus power to satisfy all Ham Radio needs. Ten Tec has designed the robust Titan II around a tube with much greater capacity than needed. The Biggie Svetlana tube is operated conservatively and should outlast any average Ham owner.

As you see from the pictures, the Titan is a fine looking amplifier. I like the gray color and the superb cabinet quality and style. If we had more room and I had more time, I would keep this one, but on to the next review. Wow! I love this Ham Radio stuff. The titan II has been replaced by the titan III. Check the Titan III web.

If you have any questions about the Titan II or any other amplifier we have reviewed, please call or email me.

If you would like to publish an article here contact Bob Hutchinson, N5CNN.