Electro-Voice RE27 N/D Microphone for Ham Radio

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Category: Ham Radio

Created: Saturday, 10 July 2021 12:39

Last Updated: Monday, 13 June 2022 10:01

Written by Rick Swenton

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This article intended to be more of a philosophical discussion than a technical review.  When you are dealing with Ham Radio transmitters and receivers, your choice of microphone can be based on science or opinion or both.  There's no real right or wrong answer.  It's kind of like asking someone how to adjust bass and treble controls on a music system. Let's start with some technical background.

The Electro-Voice RE27 N/D is a professional grade studio/broadcast microphone. Some of its features include a powerful neodymium magnet and a reinforced diaphragm dome.  This offers increased sensitivity (up to 6-dB more output), undistorted output at high sound pressure levels and an extended high-frequency response.  The mic has a 5 kHz presence rise.  This gives the sound extra clarity.  Some people say you can just do that with an equalizer.  Sure, you can.  But there's something to be said about having that already present in the mic signal.  It is a large diaphragm cardioid dynamic mic.  It's sound fidelity rivals the best condenser mics.  Unlike condenser mics, the RE27 does not suffer distortion from close-talking nor does it suffer from the "proximity effect."  The proximity effect is a change in the sound caused by the closeness of the person's voice to the mic.  The proximity effect will cause a bassier sounding voice if the person close-talks the mic. Some radio personalities use this effect as a feature sound in their shows. This effect is commonly heard on some evening shows where the host does "pillow talk" by close-talking the mic. The RE27 maintains consistent quality independent of distance between the person and the mic.  Also unlike condenser mics, the RE27 has better off-axis sensitivity.  It has a hum-bucking coil.  This helps filter electromagnetic interference and can be especially helpful in transmitting environments.

The RE27 has three with switches near the base of the mic to control frequency response.  With all switches off (switched up towards the head) the response is set to flat from 80-2,000 Hz with a 6-dB rise in response from 2,000-16,000 Hz. With one filter switch in the “roll-off” position (down), low-frequency response tilts down 6 dB from 250 to 100 Hz. A second filter switch, when in the “roll-off” position (down), creates a gentle roll-off of 12 dB from 1,000 to 100 Hz. The third filter switch, when in the “roll-off” position (down) reduces the high-frequency rise by 3 dB.

The mic has a built-in blast and wind filter and a built-in shock mount.  It is unclear how effective these are.  I suspect they are better than nothing but not perfect.  I have seen applications that have external pop filters but have never seen foam wind screens on this mic.  My own application uses the Electro-Voice 309A shock mount suspension.  The mic has a balanced 150 ohm output through a standard XLR connector,

This mic is expensive.  It lists for $499 almost everywhere.  Used ones are typically found between $400 and $450.  It comes with a carrying case and a stand clamp.  The mic is large and heavy,  It weighs a little over 3 pounds. The 309A shock mount suspension adds another $99.  I have seen professional studios with and without the shock mount so it is unclear if it is really necessary. The shock mount adds another 7.5 inches to the distance between the mic clamp and the stand threads. That means the shock mount would either raise the mic 7.5 inches above the top of your desk stand or lower the mic 7.5 inches below the bottom of your dropdown boom mount. Also keep in mind that the shock mount will add to the already heavy weight of the mic,  I had to increase the spring tension on my dropdown boom.

If you use the provided mic clamp, you should know that it clamps to the rear of the mic. This means that the mic will be front-heavy on the stand. Most of the body of the mic has acoustic screens so you can't use a shock mount that clamps to the body of the mic without blocking the ports.  The rear body area has a small portion of solid space but the mic will still be front-heavy. The 309A shock mount allows the mass of the mic to be centered and balanced on the stand mounting point.

Click Here for the RE27 N/D Mic Data Sheet

Click Here for the 309A Shock Mount Data Sheet

Now, on to the philosophical discussion.  Many of my opinions are formed by two great veteran ham radio operators.  One is Clark, N1BCG, who is a long-time broadcast engineer and Ham Radio AM expert. The other is Rob, W1AEX, who is a long-time Ham Radio AM expert, SDR expert, and online resource. Both have been invaluable consultants and trusted advisors.

It is my belief that you should strive to have the finest possible audio quality to send to your transmitter. The problem arises when different transmitters and receivers have different capabilities.  Modern transceivers from companies like Kenwood, Icom and Yaesu deliberately restrict their transmit bandwidths.  Sometimes, this limit could be as low as 2.4 kHz and even lower for SSB.  This creates courteous "good-neighbor" signals on the band. They are spectrum efficient and generally non-interfering if the audio is adjusted properly.  Some hams use ancient relics for receivers and transmitters,  There is a lot of equipment still being used today that was originally placed in service during World War II.  Much of this unmodified equipment will not have high fidelity receivers or will not be capable of full fidelity transmit.  Most of these users will not be able to tell the difference between your RE27 mic and almost any good basic mic.  Even the factory hand mic on the Icom IC-7300 sounds great to most people.  Why would you spend the money on a mic like the RE27 if most people won't notice?

Stated again, it is my belief that you should strive to have the finest possible audio quality to send to your transmitter.  My main transceiver is the Apache Labs ANAN-7000DLE MKII.  It is a software defined transceiver.  As such, all of its operating parameters are controlled by software.  With this radio I can open up the transmit bandwidth to accept the rich fidelity of the RE27.  The transmitter will still be able to be a "good neighbor" on the bands by not exceeding the set bandwidth. I will still have the same problem at the other end.  The other folks still have inconsistent receive fidelity.  At least I know at my end it is the best it can be.  The real joy comes when you and the other person both have the ability to run high fidelity audio.  This type of audio is not suited for weak signal work or seeking distant contacts.  It is meant for enjoyable conversation. Sure, the signal is wider than AM on some modern radios like the ICOM 7300, but with the SDR, the signal is tight and does not splatter adjacent users.

Is the RE-27 possibly the finest microphone ever made? Possibly. Do you need it? Probably not.  If you get it, will your world be changed?  Probably not.

Many users compared this mic with the Heil PR-40, the Audio Technica AT-2020, the Behringer B-1, and the Behringer XM8500 Ultravoice,   Various tests results did not reveal a clear winner.  That's probably because of human perception. The other mics suffer from proximity effect.  Radio listeners might not notice this unless the person transmitting is constantly changing his distance from the mic.  Many people are fond of the Behringer XM8500.  The Behringer XM8500 Ultravoice goes for about $20. Music vocalists say the XM8500 sounds as good as the industry standard Sure SM58 which goes for about $100. If you want a great dynamic mic that won't break the bank, the Behringer XM8500 is an excellent choice.  Another popular mic is the MXLBCD-1 manufactured by MXL, a division of Marshall Electronics, located in California. This is a dynamic broadcast mic.  It comes with a windscreen and internal shock mount. It retails for about $150 but I saw it on Amazon for $120 so look around.

Don't get the Electro-Voice RE27 unless you have a transmitter that is capable of showcasing its fidelity. If you get the Electro-Voice RE27,don't be disappointed if goes unnoticed on the air. You can't go wrong with the RE27 as a very high quality, best-in-class mic. That doesn't mean it will be right for you or your equipment.

Is the RE27 is worth the cost for Ham Radio use? Perhaps the answer is subjective. Is it worth it to you?

ANAN-7000 Band Change cable for ALS-1306

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Category: Ham Radio

Created: Thursday, 12 November 2020 17:07

Last Updated: Wednesday, 21 July 2021 16:25

Written by Rick Swenton

Hits: 1110

Please check the article "Last Updated" date above.  I have been periodically updating this article with supplementary information.  The main content is stable.

The ANAN-7000 can control the band switching of the ALS-1306 using its Open Collector (OC) Pins using a binary format. You can make your own data cable to connect the ANAN to the amplifier.  It will be a 5 conductor cable with a DE-9 connectors.

For many popular name brand transceivers you can purchase interconnect cables already made.  They can be costly and range from $30 to $90.  The Yaesu interface sends binary ABCD data.  The Kenwood interface uses serial RS232 data.  The Icom interface uses voltage levels.  The ANAN can perform band changing using ABCD binary over its OC Outputs.

Above is the layout of the DE-9 connector on the ANAN-7000.

From the ALS-1306 schematic the following control information can be sent into the DE-9 connector on the rear of the amplifier marked RADIO INTERFACE.  The control signal is binary. The logic level is TTL – 5v. 

The ANAN does not have an output dedicated for band control of an amplifier.  However it does have 6 Open Collector (OC) outputs that can be programmed on a per-band basis.  You can assign OC0, OC1, OC2 and OC3 to represent the ABCD binary signal to send to the ALS-1306.  Open Collector means the output can pull a signal to ground (sink) when active but floats when inactive (no voltage coming from it.) The output devices are actually FETs rated at 25v 800ma.  The band switch control voltage in the ALS-1306 is TTL, 5 volts and is well within the ANAN FET limits.

Since the ALS-1306 Band Switching input is 5+ TTL the ANAN will allow the amplifier’s input pins to float up to 5 volts and can pull them down to zero volts.  This means the ANAN and the ALS-1306 can be directly connected between their DE-9 connectors.

For reference here is the ALS-1306 DE-9 pin definitions

* If JP1 is not in place inside the amplifier the ground connection on Pin 6 is really a 10 ohm 1W resistor in parallel with two 2.7v back-to-back Zener diodes.

When Ground is not a Ground

Here's the problem with the ground connection on pin 6 of the DE-9 connector on the amplifier.  Pin 6 does not actually go to ground as the RGND label suggests.  It goes to ground through a 10 ohm 1W resistor in parallel with two 2.7v back-to-back Zener diodes.  Pin 9 on the RJ1-B connector goes to the Control Board CB2 pin 9 of RJ1-A.  There is is called GND.  But it's only really ground if JP1 is installed.

On my ALS-1306 JP1 was not installed as shipped.

Now consider this: 

if 

• you leave JP1 removed and
• you connect and use Pin 6 on the ALS-1306 DE-9 as your ground and
• you connect that to the ANAN ground on pin 1 of the ANAN DE-9

then

• you will essentially fully ground the amplifier Pin-6 anyway but through the interconnecting coax cable braid and the power cord ground wires!

endif

So here's the thing.  If you want to use Pin 6 on the DE-9 as a ground you should install JP1 in the amplifier.  You could also do as I did and use the DE-9 shell as the ground on the amplifier side of the cable.  Since Ameritron never told me what JP1 and the 10 ohm resistor was for I decided not to use it and not to connect anything to it.

I just bothers me because 10 ohms is close to ground but it's not really ground.  What are those 2.7v zener diodes for?  Do they expect a +- 2.7v signal on this "ground" line?  How does the amplifier respond to that?

Consulting with MFJ/Ameritron

According to Mark at Ameritron, JP1 is involved with the ICOM Band Control interface.  The amplifier is shipped with JP1 removed.  ICOM controls the band change using discrete voltage levels that are closely spaced.  There is some kind of ground reference problem between the amplifier and some ICOM transceivers so they needed to raise the ground potential by a small amount.  If you want a "real" ground on pin 6 of the DE-9 connector then install JP1.  It probably will work fine without JP1 because of the common ground provided by the shield of the coax and any ground wires you attached to the amplifier and transceiver.  If you installed JP1 and later desire to use an ICOM interface for band changing you may have to remove JP1.

Wiring the Interconnect Cable for the ANAN-7000

You need a DE-9 male connector for the ANAN end. If your a ANAN is an older model you will need a DB-25 male connector.

You need a DE-9 female connector for the ALS-1306 end.

You need a 5 conductor cable.  It’s a good idea to use a shielded cable.  I did not use one and have not experienced any problems.  I will probably make a new one with a shielded cable in the future. Connect the shield to ground at only one end of the cable.

Wire your cable according to the following chart.

 * If you use a shielded cable connect the shield and the ground wire from the ANAN Pin 1 to the DE-9 shell at the ALS-1306 end. Alternatively you can install JP1 on Control Board CB2.

What is the purpose of the connection called OCRef on the Anan DE-9 Pin 2?

OCRef on the ANAN is only needed if you will be driving inductive loads (like relays) with the ANAN Open Collector outputs. Whenever you energize a coil and then de-energize it, the energy stored in the coil will try to be dumped back out of the coil in the opposite polarity of the original voltage.  This voltage can be quite high and can damage a transistor that may have been driving the coil.  It is customary to put a diode in parallel with the coil with the cathode on the power supply + side and the anode on the low side of the coil that goes to the driver transistor.  The diode is called a snubber diode or flyback diode.  It absorbs that back-EMF from the coil. In the case of the ANAN these diodes are already inside the transceiver.  But the ANAN does not know what you will be connecting the transistors to and what the load voltage will be.  If you were going to drive relays that had a 12v power supply then you would connect the OCRef pin to the +12v power at the other end. That would connect all of the cathodes of the ANAN diodes to +12v.  That means that you can't mix the Open Collector outputs with relays that are not run from the same power supply. Since the ALS-1306 has a transistor buffer input with about a 4k input impedance and internally operating at +5v there is no need to worry about these diodes or protecting the open collector output driver on the ANAN.  You can safely connect the ANAN Open Collector pins directly to the ALS-1306 ABCD pins.

Programming Thetis OC Control

Next you will program the ABCD binary data into the Thetis OC Control screen. Keep in mind that the ANAN OC outputs are active low (negative logic).  That means that we need to invert the ANAN signal to achieve the desired binary value.

* There is no band definition for 60m because there is a 200w power limit on that band.
   The ALS-1306 does not have a 60m band position.

** These columns are the  Inverted Binary value flipped horizontally with X = 1 and no check = 0 

Electronic Signals OC-0 through OC-3 become Thetis values for OC-1 through OC-4 respectively

You program the OC Pins by band.  Keep in mind that the Inverted DCBA signal is applied to OC Receive Pins 1-2-3-4 as ABCD.  A binary 1 is a check and a binary 0 is no check.  This can be REALLY CONFUSING.  The wiring diagrams call the signals OC-0, OC-1, OC-2 and OC-3 but Thetis starts numbering them with 1.  (No OC-0)

If you don’t want to rack your brain about this just wire the cable according to my chart and program Thetis according to the screen shot.

Here is a screen shot of the completed programming.

There are many ways to configure the radio programming which may require a different wiring order on the pins.  Because of my digital and programming experience my thought process always has the least significant bit on the lowest signal ID.  That means when I control the binary data with the OC pins I want to have the least significant bit (A) on OC-1 and the most significant bit (D) on OC-4.  When you represent a binary number numerically on paper you show it with the least significant bit last as in DCBA.  That's why I flip the DCBA horizontally to make it ABCD so that A lines up with OC-1, B lines up with OC-2, C lines up with OC-3 and D lines up with OC-4.

Another point or contention is using the term BCD (Binary Coded Decimal) to define the control signal.  Technically this is not a BCD format signal.  BCD is not the same as Hexadecimal.  BCD is a way of counting in binary from 0 to 9. Nine in binary is 1001.  The next binary number is 1010. BCD numbers stop at 9.  You can see the bits to set the 6 meter band are binary 10 and that value is undefined in BCD.  1111 is also undefined in BCD. So even though Yeasu and Elecraft call this a BCD signal it really is not.  It's a 4-bit binary control.

If you want you can use OC-5, 6 and 7 for control of other things per band as long as you leave OC-1, 2, 3 and 4 as they are.

Plug in the cable and set the amplifier band switch to REM for Remote.  When you change the band on the ANAN the amplifier will follow and change to that band.

I believe this cable will work on the ALS-606 amplifier.

I believe this will work on older models such as the ANAN-200D by using a DB-25 connector instead of the DE-9 and wiring the DB-25 pins as follows.

* If you use a shielded cable connect the shield and the ground wire from the ANAN pin 25 to the DE-9 shell at the ALS-1306 end.  Alternatively you can install JP1 on Control Board CB2.

Good luck and happy band changing!