Aertech

T6654B Tunnel Diode Amplifier	T7670B Tunnel Diode Amplifier
Three Stage T6654B Tunnel Diode Amplifier Showing Signal Path	Two Stage T7670B Tunnel Diode Amplifier Inside Showing Signal Path Notice on the output stage that there are 3 spacer blocks between the 2 junction circulator and the tunnel diode housing. They are "tuning" blocks. The one nearest the circulator has Glyptal on it's tuning screw.

The TD amplifier combines a TD operating in the negative resistance region with a matching circuit and a circulator to separate the incident and reflected waves. Since the isolation of a single junction circulator is around 20 dB the gain of each stage needs to be less than that to prevent oscillations.

These amplifiers have two very important properties for space applications. First the bias voltage and current are both quite low so the power consumption is also very small. The Tunnel Diodes are heavily doped and so are not effected by radiation.

We sold some TDAs that had a built in "D" size Mercury battery and an on/off switch. One came back many years later because the battery had run down, but the amplifier worked fine with a new battery.

TRW acquired Aertech to gain control of the space qualified TD amplifiers that they were buying from us. We then also built space qualified hardware on Cost Plus Fixed Fee (CPFF) contracts. On these contracts it was common to add as much cost as possible because you got your profit on the total cost. The means doing things like having your own Scanning Electron Microscope (SEM) instead of contracting that out.

T5530 Unified S-band Tunnel Diode Amplifier

On the T5530 unified S-band amplifiers I worked on used for satellite telemetry the bias circuit included a 5.1 Volt Zener diode. That was because it has near zero temperature coefficient. The bias circuit also included a position for a Balco (Wiki) positive coefficient resistor and a position for a Veeco negative coefficient resistor (Wiki) was well as some fixed resistors. That way each amplifier could be customized to have constant gain over a mil-spec temperature range. This was done using a temperature chamber with decade resistor boxes connected to the circuit positions for the Balco and Veeco resistors. A number of amplifiers could be done in parallel.

J3

Probably the DC input

J4

700 Ohms - probably the relay coil

Circulator

When the AMY6 polarity testers is moved around the top face (label) it shows the relative rotation direction of that junction:
North near the output
South over the gap between Tunnel and Amplifier
North near the Input

It also had an input so that the bias on the Tunnel Diode could be set to the valley. In this position the amplifier would act as an attenuator so large signals could be handled.

Fig 1 Label: Aertech Tunnel Amplifier Model No. T5530 Serial No. 446 Band: 2.2 - 2.3 Gc FSN 5826-905-1748	Fig 2 J3 & J4: 0.245" dia x 0.21" hi above hex flange. one is the DC input the other is the relay drive for valley voltage bias. Under the set screw is a gain adjust pot.

TD detectors, or more properly called Back Diode detectors use the diode without any bias. The diode characteristics are such that the impedance is near 50 Ohms and so is not only a good match to the RF but also to the video output. This is very important when detecting pulses since the video bandwidth of the TD detector is much wider than of a crystal detector. Because of this TD detectors are very useful in RADAR countermeasures receivers.

B-1 B-2 B-3

Detector/Mixer

Some of the above detectors have bulges and discoloration, so maybe these came from a dead group.
3693103 Wideband Detector for use in Coaxial Transmission Lines, R.B. Mouw, Sep 19 1972 - replaceable diode (maybe not tunnel diode?)

Detector p/n Prefix Letters

D - Detector
DT - Detector with TNC input
DB - Detector with BNC input
DM - Detector in Miniature configuration (SMA connector input)
DMM - Detector is sub Miniature configuration (SMA connector input)
DO & DOM Detector 3mm input & output

We used tunnel diode detectors (type-N input) mounted on Narda couplers as mixers for Noise Measurements. AIL tube type amplifiers fed the HP 340 NF meter. Mostly used the HP noise source with a type-N output but sometimes used a hot-cold noise source that required liquid Nitrogen.

Transistor Amplifiers

There were various types.
The UHF amplifiers were made by Tom Olsen and were lumped element designs.
The first generation L and S-band telemetry amplifiers were Bob Mouw designs where the coupling was based on inter-digital filters. These have excellent out of band rejection. They are also difficult when it comes to measuring noise figure since this is a double sideband measurement with the offset equal to + and - 30MHz. When measuring near a band edge if one of the sidebands is outside the filter then the NF appears to be high.

UHF

The VHF - UHF amplifiers made by Tom Olson (Olsen Technology) using lumped elements mounted on a solid copper clad fiberglass board (not etched). The parts were held in place by drilling a hole though the board and inserting a Teflon standoff (some with just a post and others that were feed through).

L (1435 - 1540 MHz) & S (2200 - 2300 MHz) Band Telemetry

These amplifiers were made by Bob Mouw. They were inter-digitated filters at each coupling stage. There is a huge advantage in that any out of band intermodulation products are eliminated greatly improving the intercept point and rejecting out of band signals. Both very important in receiver preamplifiers. But, this also made it difficult to measure the noise figure. That because the simple setup we used with the coupler and TD detector was a double sideband measurement so that you were measuring the NF at the LO + 30 MHz and the LO - 30 MHz. So if you tested at the specified band edge one of those would be 30 MHz out of band and because of the steep skirts on the band pass filters the NF would look bad to a government inspector that was not microwave savvy.

L and S band telemetry were the two most common applications for this type of amplifier.

Bob liked to put a lot of tuning screws into his designs. These had a number of them for each stage so you could "tune it up".
That means that none of them worked as assembled and all of them needed a lot of tuning.

	It's my hope that this is one of the Bob Mouw design units that has the interdigitated resonators.
	The holes in the bottom were tapped and used to mount the various amplifier stages. At the input and output there were "half filter" sections that just had one finger. The amplifier stage has one input finger and one output finger. So based on the hole pattern I'd say there's an input and output stage on the ends and 4 gain stages between them.

Wide Band

These were designed by using S-Parameters after the HP 8410A was introduced. There was a company that had an automated 8410 system and would test transistors and supply us with the S-Parameters. The first generation microwave transistors were Germanium and made by TI.

We built a transistor tester based on the GE Transistor Manual and used it to measure the DC parameters of the transistors and correlated these with the RF performance. Once that was done it was possible to buy a batch of the same p/n with the proviso that TI would not have culled the better transistors. This saved a lot of money since buying tested transistors was expensive.

Taming the out of band gain was required to prevent oscillations.

Detector Log Video Amplifiers (DLVA)

Final Report for Naval Research Labratory, contract: N00014-74-C-0020 for two models: 2.6 - 8.0 GHz & 6.9 - 18.0 GHz. DTIC_ADA032880
eBay Serch Term: "(Aertech,TRW,FEI) Detector Log Amplifier"
FEI Microwave LDS 1559
TRW Microwave LDS 1554 8 - 12 GHz

This was on eBay " from a multichannel electronic warfare receiver system that got scrapped"

External limiter is marked: Aertech, A9X712BI

Semiconductors

For the first few years all the semiconductors were purchased from outside vendors and were typically in small cylindrical ceramic "pill" packages.

Diodes

The first diodes that we made were Tunnel diodes for amplifiers and back diodes for detectors. This was a manual one at a time process, i.e. not using wafers or masking. Since Tunnel diodes are highly doped there is no need for a clean room, i.e. it was more like a dirty room.

It's difficult to test tunnel diodes because between the voltage where the peak and valley are located the diode exhibits negative resistance. In this region the diode will oscillate. To prevent oscillation the diode needs to see a real resistance that's lower than it's negative resistance, something that's very difficult to do over a frequency range that covers DC to 60 GHz. The way we did it was to use a transmission line that was loaded with lossy material (either cylindrical or a flat plate transmission lines) and terminated with a fixed resistor. A bridge circuit can be used to eliminate the fixed resistor from the measurement allowing the true I-V curve to be seen on a Tek 567 Curve Tracer.

The next stage was to make Schottky diodes for use in detectors and mixers, then PIN (Wiki) and Varactor (Wiki) and Step Recovery (Wiki) diodes were added. These were made on 2" diameter wafers which at that time were obsolete for digital ICs and so the equipment was available at low cost. Since we were dicing the wafer into chips that were 0.015" x 0.015" the yield per wafer was on the order of 10,000 chips/wafer there was no motivation to move to larger wafers. The need for a clean room may have been the main motivation to move from Mountain View to Sunnyvale. Sunnyvale was the first city to have a building code that allowed for both office space and hazardous materials in the same building (code section H6).

The first clean room was located in the center of the building with windows. This allowed the exhaust clean air to bleed into the dirty surrounding space. It also allowed a factory tour where you could see most of the fab without putting on a clean suit. A big problem with this arrangement is that you need to move hazardous material through the office/work areas. Which is not good if there's a spill.

The same model numbering system was carried over to the diodes.
A1Gnnn - Amplifier Tunnel
A1Ennn - Detector Tunnel
A2xnnn - Schottky
A4Snnn - Step Recovery
A5Snnn - PIN

Testing Tunnel Diodes

I-V

If you put a tunnel diode on a curve tracer it will oscillate in the part of the curve where there's negative resistance. Once it starts to oscillate it may keep going even after the operating point has moved out of the negative resistance part of the curve. So the diode needs to be stabilized by shunting it with an impedance that's lower than the diode negative resistance at all frequencies below the cutoff frequency. Fco could be in the tens of GHz so the stabilization circuit needs be based on microwave design ideas rather than lumped elements.

There were a couple of designs. They were both based on loaded lines. One was a coax line and the other was based on slab line, i.e. a couple of Aluminum plates that sandwiched a block of lossy material.
In both cases a regular carbon resistor was connected in parallel with the stabilization device.

A special I-V test box connected to any scope. It included provision to balance out the DC resistance of the carbon resistor so the I-V plot looked normal.

Capacitance

Calculating Cutoff Frequency

See my Microwave Diodes web page for some details on them.

Module Products
These were made using raw semiconductor chips in packages with hermetic glass to metal seals that had a nominal impedance of 50 Ohms.
This is the product line I developed.

Limiters

If glass packaged diodes are used the inductance of the lead wires limits the upper frequency to below microwave frequencies. This was my first attempt to make a limiter and it didn't work. In order to work with microwave signals raw diode chips need to be used.

By placing a couple of fast PIN diodes across a transmission line you can get a circuit that passes low power levels but that reflects high power levels. These have an internal DC return (the A9L100 series).

In order to use raw chips a new packaging technology was needed. At this time HP had a series of microwave components that were packaged in a cylindrical package and was sealed by welding the ends. This was both an expensive and difficult to use package. I came up with a similar package which had a protruding lip instead of the recessed shoulder that was on the HP package making it much easier to integrate into a final housing. I also used a solder seal instead of the weld used by HP. This is both lower cost, lower temperature but also allows repairing a module.

I think Fred and Harold setup a local company to make the glass to metal seals and to weld them to the central part of the modules.

A later limiter topology used a shunt PIN diode and an opposite polarity Schottky diode, with DC blocking caps on each end. (The A9L200 series)

Switches

A simple microwave switch is just a diode to ground. When back or zero biased the open diode lets the microwave signal go past, but when forward biased the diode reflects the signal keeping it from getting to the output. If the diode has a short lifetime then the signal interacts with the bias, like in a limiter where a DC return is provided. But if a diode with a lifetime that's long compared to the period of the signal then the signal does not change the bias and you have a switch.

Wide bandwidth switches require a series diode to isolate the off output arms. For a microwave switch these need to be beam lead PIN diodes with very low series capacitance.

Narrow bandwidth switches can be made with all shunt PIN diodes by spacing the first shunt diode a 1/4 wavelength from the common junction.

Making a bias-T network that appears as an open over the full 0.1 to 18,000 MHz frequency range is far from trivial. HP had some of these bias tees.

Schottky Diode Detectors
A Schottky diode (Wiki) detector needs to have a DC bias applied to get the diode impedance down to the design value which may be a few hundred Ohms. A matching circuit is used to get a good VSWR in a 50 Ohm circuit.
The module type (where a raw Schottky diode is used) are the A9D--- part numbers.

The most common circuit consists of a microwave input matching circuit which may have the diode mounted at the far end with a stitched bonding wide to a bypass cap and on to the output. The polarity can be reversed by mounting the diode on the output bypass capacitor. The inductance of the bonding wire between the matching circuit and output capacitor is very important and so often was not a wire but rather a gold mesh and that was hand cut from a sheet and typically contained an odd number of strands so that the center strand could be bonded to the diode junction thus keeping the mesh on the centerline of the cylindrical module.

Limiter-Detectors
This was a logical outgrowth of having both limiters and detectors in the cylindrical package. The first ones were made by putting a limiter module and a detector module into a long cylindrical package. The production units were made using a single long module.
Also see:
Radar Warning Receivers
AM-6536 / ALR-54 Radar Warning Receiver Front-end

Comb Generator
This was a cylindrical module containing a matching circuit to a step recovery diode (Wiki).
Model numbers look like A9G100BR. Similar to the HP 33005A/B module, but easier mechanical integration.
The input was something like a half watt signal at 100 MHz and the output would be a series of signals every 100 MHz, i.e. 100, 200, 300, 400, . . . . MHz.
Hence the name "Comb" generator because that's what it looked like on a spectrum analyzer.
Some HP spectrum analyzers have one of these built-in to provide a test signal at many frequencies.
Another way to use these is to use a filter (sometimes a tuned YIG filter) to select a specific frequency and use that frequency with a mixer to generate a new frequency or in a microwave counter, like the EIP counters.
A very special comb generator was used in the HP Large Signal Network Analyzer (Non Linear network analyzer) as a calibration test signal.
6812714 Apparatus for collecting signal measurement data at signal ports of an RF and microwave device-under-test, under different impedance load conditions, Agilent

See my Diodes web page under SRD for more information.
The HP 8406 is a bench top instrument that's a comb generator.
HP App Note 920 - Harmonic Generation Using Step Recovery Diodes and SRD Modules
HP Components for Control and Conversion of RF and Microwave Signals 1973 - 1974 - pdf page 16 SRD Modules
HP Diode & Transistor Designers Catalog 1980 -

3401355 Step recovery diode frequency multiplier, Peter H Kafitz, Ryan Aeronautical, 1968-09-10, - Contains tank circuit so maybe only a single frequency output. Can be used in phased array RADAR.

Power Dividers

These were Wilkinson type (1/4 wave lines) (Wiki) and were narrow band. The main frequency range was 2.2 - 2.3 GHz to support the then new unified S-band telemetry (Wiki, NASA: Apollo Unified S-Band Tech Conf NASA SP-87.pdf 1965). There were a number of designs with 2, 4 or 8 outputs and with various connectors like SMA, TNC, Type-N.

There is a resistor across the output ports that's located a quarter wave from the "Y" junction. If a signal is fed into OUT1 and IN is terminated with 50 Ohms then the resistor is across a half wave path and so OUT2 sees isolation. For a signal fed into IN the resistor is at the same potential on the OUT1 and OUT2 paths and so contributes no loss, i.e. the insertion loss would be a fraction of a dB higher than 3 dB.


M3201 Power Divider 500 to 1000 MHz	M5202 Power Divider 2.2 to 2.3 GHz (S-band telemetry)

Circulators (Wiki) & Isolators (Wiki)

At some point the design and manufacture of circulators and isolators was brought in house. Prior to that an outside captive company made the circulators and isolators used in the Tunnel Diode Amplifiers. The electrical specs are very tightly coupled. For example if you tune the unit for very good return loss at some frequency the isolation will be very good at that frequency and to a lesser extent so will the insertion loss.

Note: A circulator has 3 connectors and an isolator has 2 connectors and a built-in termination.

Sources

Don't remember much about these. Found unit on eBay.
Marked VCXO Amplifier
Model: S2704
Serial: 0297
QA Stamp date: 6-26-84
Connectors (left to right): RF OUT (SMAf), -12V, Gnd, +15V, V_T (SMAf)
TRW (Aertech, FEI
Micorwave) Source S2704

Polar Frequency Discriminators (aka Instantaneous Frequency Monitor)

Aertech PD4018 Polar Frequency Discriminators PFD
Instantaneous Frequency Monitor IFM

2 to 4 GHz input at bottom center.
Output DC coupled signals on the 4 detectors.
If all the detectors have zero to positive outputs (or zero to negative outputs) then the X pair and the Y pair will go into differential inputs so that the combined X (and combined Y) channels will be bipolar. That way when fed into the X and Y inputs to an oscilloscope you will see a circle when a sweep from 2 to 4 GHz is the input. The radius of the circle is the power and the angle of the spot is the frequency. In the actual system the differential amps would feed very fast A/D converters.

These were strip-line components that typically had four microwave detectors as the outputs. A number of them could be cascaded where the delay line length causes them to work like a gas meter so each added unit provided finer resolution. They worked great on pulsed signals, but had a problem with CW signals.
Bill Rocko (spelling?) developed the product line. He also was expert in making scale models where the dielectric constant also needs to be scaled.

3015776

Indicating fluctuations in frequency and amplitude,

Feb 9, 1957 - used with phonograph records
3061780

Polar displayer,

Jr Chester B Watts,

Alford Andrew,

Mar 19, 1956

3083336 Direct reading, 360 degree phase meter, Poirier Jules Hubert, Ryan Aeronautical Co, Jul 12, 1960,
3135917 Frequency sensitive wave analyzer including frequency sensing phase shifting means, Ethridge C Best, Martin R Richmond, Sanders Associates Inc, Sep 11, 1961
3395346

Phase and instantaneous frequency discriminator,

Kincheloe William R, Wilkens Mark W, Research Corp, Mar 24, 1965,
3517309 Microwave signal processing apparatus, Carl W Gerst, A NAREN MICROWAVE Inc, 1970-06-23 - This is the basic idea, 4 channels drive a scope.

Calls:
3423688 Hybrid-coupled amplifier, Harold Seidel, Bell Labs, 1969-01-21
3444475 Broadband hybrid-coupled circuit, Harold Seidel, Bell Labs, 1969-05-13

3518541 Digital Phase Measuring Set, Jun 1970
3568067 Frequency Discriminator with Output Indicitive of Difference Between Input and Local Reference Signals, Collins, Mar 1971
3956706

Miniaturized millimeter wave instantaneous frequency discriminator,

David L. Saul, US Navy, May 11, 1976
4144491 Frequency measuring apparatus, Raytheon, Mar 13, 1979
4414505 Microwave instantaneous frequency measurement apparatus, Nov 8, 1983

Digital Correlator

Mixers

Bob Mouw was the first person to make a double balanced mixer that worked at microwave frequencies. Prior to his invention double balanced mixers were made using a couple of ferrite balun transformers and a "ring" connected diode quad. Their upper frequency limit was around 2 GHz. Bob took the classical circuit and made a "dual" that used a "star" diode quad and hybrid coaxial transmission line transformers. I helped do the mathematical analysis for this mixer. You can consider the diodes as switches that are turned on and off by the Local Oscillator. The two states either pass the input signal or invert the input signal. Doing an FFT on the waveform gives all the frequency domain outputs of a mixer, less those that are cancelled due to the mixer balance.

The ides is to make the dual circuit of the ring double balanced mixer.

The mixer equation is:
IF = +/- m * RF +/- n * LO
given a desired RF frequency and an LO frequency there are many IF frequencies generated.
Orin Gobby (spelling?) was a expert when it came to receiver design. Choosing the LO frequency to minimize spurious signals is as much an art as a science. You can make a plot of LO, RF and IF frequencies all normalized and they choose the LO and IF frequencies in order to get the desired spur free frequency range.

Semiconductor mixer performance has a limit to how large a signal can be handled. WJ wrote some app notes trying to get at the cause. The answer can be found on my microwave diodes web page.

"Broadband Double Balanced Mixer/Modulators" by R. B. Mouw and S. M. Fukuchi,
published in the Microwave Journal, pages 133-134, March 1969.
Steve Fukuchi worked with bob on the mixer line.

R. B. Mouw et al, "Broadband Double Balanced Mixer/Modulators", Mar. 1969, Microwave Journal, Part I, 4 pages.
R. B. Mouw et al, "Broadband Double Balanced Mixer/Modulators", Microwave Journal, 6 pages, Part II.

3512090 (Google) 5 /1970 HYBRID JUNCTIONS AND MIXERS AND MODULATORS CONSTRUCTED THEREFROM, Mouw Robert B
    Issued/ Filed: May 12, 1970 / Oct. 18, 1967 455/326; 333/24R; 455/331 - Is the first version of the Mouw mixer pattern
    Note: the coax lines have had their center conductor heated and pulled out and replaced with a new centerconductor of smaller diameter
     (i.e. the 50 Ohm line is transformed into a higher impedance line).

3818385

(Google) Hybrid junction and mixer or modulator, R.B. Mouw, Aertech,

Jun 18, 1974, 333/26, 333/243, 455/326, 333/238, 333/35

3512090 5 /1970
HYBRID JUNCTIONS AND MIXERS AND MODULATORS CONSTRUCTED
THEREFROM

The diodes shown on the first page are in glass packages. Later there were much more advanced versions built. These typically were made in octave bandwidths.

3818385 06/18/1974 HYBRID JUNCTION AND MIXER OR MODULATOR 333/26; 333/35; 333/238; 333/243; 455/326

Mouw-"Broad Band Hybrid Junction & Application to the Star Modulator" Nov. 68, IEEE-Transactions on Microwave Theory & Tech. Vol. MTT-16, No. 11.
"Compensated-Balun;" Oltman, March 66; IEEE-Transactions on Microwave Theory & Techniques pp. 112-119.

3638126 01/25/1972 HIGH-FREQUENCY CONVERTER - Bob later worked for Spacek Labs on millimeter components.

Crystal Detector

Came across another Robert B. Mouw patent for this detector. Unlike pretty much all the other detectors made at Aertech, this on uses a classical crystal (similar to the 1N21 but in a much smaller package). This probably was to offer an alternate to the common HP 423 type detector in the same form factor for general lab use, i.e. Type-Nm input and BNCf output.

This may or may not be related to the Tunnel Diode I-V test system developed at Aertech. It used a transmission line in parallel with the normal I-V circuitry.

3693103 Wideband detector for use in coaxial transmission lines, Robert B Mouw, Aertech, 1972-09-19, 324/95; 333/125; 333/206 -

Calls:
2454062 High-frequency conductor having a low impedance movable electrical contact device, UK,
3038086 Radio frequency logic circuits, RCA - have parallel paths
3350655 Electrical crystal unit for use at microwave frequencies, Theodore S Saad, GTE Sylvania, 1967-10-31, -
3559109 Microwave switch, Alcatel, 1971-01-26, - parallel paths
3638141 Compact, high-power, high-efficiency silicon avalanche diode l-band oscillator, RCA, - parallel paths

What was the model number, D12? Let me know.

Aertech Industries

Background

Big Picture

Company Names

Locations & Dates

Products

Tunnel Diode Based

Tunnel Diode Amplifiers

T5530 Unified S-band Tunnel Diode Amplifier

J3

J4

Circulator

Tunnel Diode Detectors

Detector p/n Prefix Letters

Transistor Amplifiers

UHF

L (1435 - 1540 MHz) & S (2200 - 2300 MHz) Band Telemetry

Wide Band

Detector Log Video Amplifiers (DLVA)

Semiconductors

Diodes

Testing Tunnel Diodes

I-V

Capacitance

Calculating Cutoff Frequency

Module Products

Limiters

Switches

Schottky Diode Detectors

Limiter-Detectors

Comb Generator