CB World Informer December 1996 Issue, Midland 79-290 Review
The Midland 79-290 is the smallest sideband mobile available today. It measures only 2" high by 6.25" wide by 7" deep. The small size combined with the detachable face makes it possible to safely mount it permanently in many vehicles.
This is a new generation of CB radio designed and manufactured in Korea. Instead of producing a convertible 10 Meter amateur they have used the reverse philosophy. Producing a convertible FCC approved CB. Maybe the industry is trying to keep ahead of Uncle Charlie. It could just be a matter of time before Uncle Charlie wakes up and realizes that the 10 Meter loophole is being stretched beyond its limits with the Connex, SuperStar and Galaxy type 10 Meter only units. It's obvious that they are DX radios with their band switches disabled.
The Midland has some unique features for a legal SSB CB unit. It has dual watch capability. This option gives the operator the ability to select and monitor a second channel during normal operations. Also four programmable memory channels can be selected at a push of a button or scanned for activity if desired. The LCR button stands for last channel recall and returns the unit to the previous channel when depressed. This allows quick jumping between two channels. In addition a fine and coarse clarifier are provided for easy tuning while on the move.
Opening the unit and at a quick glance you realize that this isn't a copy of an earlier product. The only similarity between this radio and any other unit is in the transmitter final output. The final output stage uses two 2SC1969 transistors instead of the traditional single transistor. This is the same configuration used in the export and most 10 meter radios that have 30 - 40 watt PEP output.
The only difference is they employ the 2SC2312 transistors in the final stage. Three variable resistors are used to adjust the AM and SSB output of the transmitter. VR8 is the SSB ALC control, VR3 is the AM power adjustment and there is a VR for adjusting the AM modulation.
What's missing is the driver and final bias adjustments. I find that these adjustments are important in getting the cleanest signal on sideband. But I know that most factories don't do a fine adjustment on these controls anyway.
This Midland unit tuned up to 28 watts PEP and 8 watt dead key swinging up to 25 watts on AM. The audio on sideband had a slight warble that I was unable to correct with the normal schemes I've used in the past. The audio was clean on AM and when the sideband output was reduced to 12 watts PEP.
The stock mic supplied is adequate but nothing special. A good quality mic would improve the tone quality but wouldn't improve the warble. A warble is usually caused by poor voltage regulation at the PLL/VCO or in the clarifier circuit. As the output was turned up I notice the display lamps dimmed excessively possibly indicating a poor path for the 13.8 voltage supply. This could be the reason for the warbling transmission.
Frequency modifications are enabled by changing solder shorts on the PC board in the detachable face and are user selectable by way of the front panel. The five digit frequency display comes in handy once the expansion is made. No road map needed here. Once the deed is done there are three options to choose from.
The normal default is strait forty channels. The second option is expanded coverage of 240 channels from 25.615 MHz to 28.305 MHz. And the third option is 10 Meter coverage from 28.000 MHz to 29.700 MHz by 10 KHz steps totaling 170 channels.
To switch from 40 to 240 channels depress both the "DW"' and "9" buttons simultaneously while turning the power on. At first a "D" symbol will appear on the LCD display. Bands "A"' through "F" can be selected by depressing the "19" button. To return to the regular 40 channel mode just repeat the steps above.
To switch from 40 channels to 10 Meter coverage depress both the "LCR" and "Mic" buttons simultaneously while turning the power on. 28.000 MHz will be displayed on the LCD display. As before to return to 40 channels repeat the steps above.
It's not possible to switch directly from 240 channel mode to the 10 Meter mode or visa versa. The expanded modes can only be accessed from the 40 channel mode. This front panel selection of expansion is great if you don't want Uncle Charlie to catch you with extras or unauthorized out of band or ham band use.
Memory back-up is achieved with a rechargeable battery in the detachable face of the unit. Power must be applied to the radio for 120 hours to fully charge the battery. A fully charged battery will hold the memory for 240 hours. Also the face or control head must be removed from the radio to achieve 240 hour memory back-up. If memory power is lost the radio returns to the default 40 channel mode.
The S meter looked flashy but after close inspection I realized the segments jumped by two for readings above S9. I don't understand why they provided all the bars in the meter if they weren't going to make proper use of them. 'Me meter reacted the same in the RF mode too.
Unfortunately the receiver was the biggest disappointment in the radio. When attached to a base antenna I was almost unable to determine what channel some operators were on because they were bleeding over all forty channels.
I could understand every word. The only way I could tell the channel they were on was when their audio sounded clear. I've never encountered this level of splatter in any radio before.
When checking the offending signals with a Tram D201 I found their signals to be between 10 to 20 dB and they were hardly noticeable on the adjacent channels. I also did some research and found that I wasn't the first to experience this problem with the 79-290.
Although the problem would be less severe in mobile operation, it would still be difficult to communicate with the low level signals splashing the receiver. It would be frustrating on interstate highways or in areas heavily populated with CBers. I've heard stories of drivers throwing radios out the window for less.
In summary I must say I'm impressed with the features and size of the radio. It has real potential to be a big player in the CB market. For that to happen they need to address some problems. I think the battery life is inadequate.
Six days of back-up isn't really enough, especially when the battery charge rate is so slow. It takes 3 days of uninterrupted 12 volt supply to the radio to fully charge the battery. Second all the segments of the meter display should be driven separately for proper resolution. Third the sideband warble must be resolved.
Finally the receiver must be improved or redesigned, the radio isn't useable in its present condition. One other feature that I'd like to see is 5 KHz steps in the expanded modes. I hope Midland bites the bullet and corrects the problems, I know I could sell many of these radios. Especially if the HR2510s are really history. ©CBWI
Cobra/Uniden SSB Chassis Mod UPDATE
This is a correction of the article in last months issue. The value for R131 was omitted. I've added arrows to the drawing for the three resistors that change value for quicker identification.
Reference shaded areas to the right.
|8.2K from the emitter of TR26 to 8 volts constant|
|R131 from 10K to 4.7K|
|R159 from I8K to 33K|
|R228 from 560W to 33K|
|C109 for 10µf|
You may wonder why CBs are locked on frequency. Back when sideband was first introduced to the CB community, The clarifiers would move both transmit and receive together. This was legal because the tolerance of the transmitters was +/- .005 %. This means the radio had a frequency range of +/- 1.3 KHz from center frequency.
The industry used this leeway for the clarifier. They also designed the circuits to be modifiable to increase this range substantially. Back in those days everyone wanted to go down 10 KHz to make use of the RC or "A" channels.
They used 3A, 7A, 11A, 15A, and 19A for sideband to get away from the congestion of channel 16 or what ever happened to be the local sideband channel. When the "A" channels were busy operators dropped 5 KHz to make use of other unused space between 15A and 16.
This activity upset the FCC and when they approved additional channels new stringent regulations were imposed including the one that mandates all transmitters must be locked on frequency. This made anything more than a two person conversation difficult.
Radios were off frequency and any third party sandbagger would go nuts turning the clarifier back and forth. Everyone wonders why the factories let radios out that are off frequency. By the letter of the law, they're not.
The new tolerance is +/- .002% giving them a leeway of just over +/- 500 Hz and still be considered on frequency. In production the radios are set before having time to reach full operating temperature. This is one reason for new radios being off frequency out of the box.
Uncle Charlie's actions made it necessary for most operators that wanted to use sideband to contact a technician and while at the shop they're usually told about extra channels and so on. The customer most often decides to get everything done at one time. Charlie's plans backfire again!
All sideband clarifiers can be unlocked and expanded to a degree. Some, like the Cobra 148GTL and 200OGTL will slide +5 KHz and -12 KHz without changing parts or adding chokes. Although it's nice to have capabilities to go anywhere, the more range a clarifier covers the more touchy it is to use.
President Jackson Unlocked Clarifier Mod.
Surprisingly there are still Jacksons in use with the fine clarifier unmodified. From the factory the fine clarifier only changes the receive frequency while the coarse control changes both transmit and receive. With this scheme it's almost impossible to find center slot. The solution is to unlock the transmitter so the fine changes both transmit and receive.
|The following is a simple, effective way to unlock and increase the range of the clarifier:|
|L14 Controls AM/FM||= 15.5100 MHz|
|L15 Controls USB||= 15.5125 MHz|
|L16 Controls LSB||= 15.5075 MHz |
Cobra 148GTL & Uniden Grant XL Unlocked Clarifier Mod
Many of you already know that the 148 GTL and Grant XL are the same radio. The same board was used in the Cobra 2000 GTL. These chassis are remarkably stable after the clarifiers are opened and expanded. Although they do drift until warm, it's not much compared to the DX radios that have the same clarifier capabilities.
|The following will unlock and keep the standard clarifier range:|
|The following instructions will expand the clarifier range after it is unlocked: |
|L23 controls AM ||= 34.7650 MHz|
|L22 controls LSB||= 34.7635 MHz|
|L59 controls USB||= 34.7665 MHz|
|The Cobra 200OGTL is the same as above including the following steps:|
The dual controls on the 2000 are easy to deal with for the fun range of the clarifier. All that's needed to drop 5 KHz or 10 KHz is to get close with the coarse and trim in with the fine control. The single controls are more difficult but the schemes listed above make them fairly easy to tune at the center slot position.
A dual potentiometer can be added to most radios. The only limiting factor is the space available in the front panel. Radios with the controls mounted flush to a circuit board behind them would take more work than it would be worth.
The following is a schematic for a fine/coarse clarifier control:
|These could be two separate controls Fine Coarse but one dual potentiometer would be best. The 2K resistor can be larger or smaller depending on the range you prefer from your fine control. Decrease the value to increase the fine range and increase the value to decrease the fine range. |
Cobra 142GTL & Uniden Washington Clarifier Mod
This chassis requires the addition of a 5.6ph choke in series with the varactor diode D20 to get any additional slide range from this clarifier. The use of a super diode would give the radio a swing of more than 10 Khz but they seem to be unavailable for now. Adding the choke will give you more than 5 Khz down and 2 Khz up.
|The following instructions will open and increase the clarifier range: |
The center slot is now at 3 O'clock and 5 KHz down is approximately in the 9 O'clock position. Radios will vary due to the tolerances of all the parts in the circuit and the characteristics of the crystal in the circuit.
If the 142 has been channeled up then the crystal has been changed from an 11.1125 MHz to a 11.3258 MHz part. Depending on the manufacturer of the crystal the radio may slide more or less than the factory unit. Also the center slot position of 3 O'clock may not be able to be obtained. ©CBWI
Uniden Grant Clarifier Mod
This one is similar to the Washington chassis but already has the 11.3258 MHz crystal in the circuit. The 5.6µh choke is needed for the extra range and a super diode in place of the stock varactor diode would give the best range.
|The following instructions will open and increase the clarifier range:|
There are other radios that use these chassis and the mods. would be the same. You'll just have to determine which chassis are the same by looking for commonalties for yourself. ©CBWI
Uniden PC 122, PRO 640 & PRO 810 Clarifier Mod
These radios use a lower cost chassis and you can just squeak 5 KHz down from them using a 5.6 µh chock in series with the varactor diode D23.
|The following instructions will open and increase the clarifier range:|
The President AR144 and Cobra 146GTL have similar circuits and the above instructions are adaptable to them. ©CBWI
Review Of The NorthStar DX880HL
The new NorthStar line of radios are copies of the Galaxy line. These radios are said to perform as well or better than the Galaxy units. The one reviewed was made in China. In the past I've seen good and bad quality from China. Uniden has a factory in China and their products are well made. Some other manufacturers have plants in China and the quality leaves a lot to be desired. We'll just have to put it through its paces and lift the covers for a peek inside.
Thumbing through the Users Manual I noticed that the frequency stability is claimed to be .001%. If this is true this radio is far better than the Galaxy counterpart. The Galaxy SSB chassis drift more than any other that I'm aware of. A claim of 361 channels also surprised me, the radio only covers 28.315 MHz to 28.755 MHz out of the box and this is only 45 channels with 1OKhz spacing, a bold claim under the circumstances. 'Me manual does have information covering all the features of the unit.
It also has sections on mounting, antenna & tuning, tips for antenna adjustment, receiving SSB signals, microphone schematic & wiring, one year warranty information and an 800 number for help & service.
The manual is better than most. The tips for antenna adjustment had useful information that could be used as a check list for debugging a problem installation. The section on receiving SSB signals is quite good and would be useful for first time sidebanders or operators that have had problems tuning in on sideband. Me microphone instructions are filled- with complete details geared for someone who has never wired a mic before.
Removing the radio from the bag I was impressed with the deep black finish on the face. It was reminiscent of the AR-3500 by Clear Channel Corp. The six little push button switches have a more solid feet to them than the Galaxy. Also the switches and controls have a quality feel to them.
I decide to apply power to the unit before I opened it because the specification on frequency stability was intriguing me. Could they make this radio that stable. This would mean that the radio would only drift +/- 288 Hz in the worst case. Well, I turned it on and immediately checked the frequency.
A half hour later I rechecked the frequency and found that the radio drifted approximately - 870 Hz. This is about .003% or three times the specification. I believe this is a little less than the Galaxy. They seem to drift I KHz to 1.3 KHz cold to warm. Keep in mind the winter mobile operation will be worse. The tests were done at room temperature. It would be desirable to see the radio improved in this area to match the specification claim.
Below is a diagram indicating the location of the controls.
If you're familiar with the Galaxy DX88 you can see that the control function and placement are identical between the two units. Before removing the screws I notice there were no Warranty Void labels! On the inside the story is the same, component and board placement are the same in both radios. The conversion is the same for the two.
Quality of workmanship is better in the NorthStar. They even replaced the nylon screw holding the frequency counter module. These screws are usually stripped from the factory and eventually snap off within a year of operation leaving the frequency counter floating around in the chassis.
Tune-up is the same a the Galaxy with the same results. Sideband output was 35 watts PEP while AM was 10 watt dead key swinging to 30 watts fully modulated and I watt dead key swinging up to 15 watts with the power in the low position.
Low power is great for driving and amplifier, but the sideband power would have to be reduced internally as the low power switch doesn't effect sideband in these units. The audio was clear in all modes and the receive is as sensitive as the other unit. 'Me receive audio was crisp, clear and without that annoying high pitch static found in the newer DX radios.
On the air tests went well, the adjacent channel rejection is comparable to the DX88. The echo is also unchanged with the same amount of control and clarity.
|My wish list for this radio is as follows:|
I f this radio had these additional features I think it would be the perfect all mode mobile radio.
|What I like about the NorthStar DX88OHL:|
If this is the type radio you're looking for I would recommend this version over the Galaxy. The warranty is worth the difference in price and it's a good feeling to be able to contact someone if you have a problem. With other radios you may go through an owners' manual from cover to cover and not find so much as an address for the company that supplied the product.
This doesn't exactly give you a warm comfortable feeling. This to me is the best reason to consider NorthStar. NorthStar is a product of Wireless Marketing Corporation, 3701 N. Algonquin Rd. #750, Rolling Meadows, IL 60008. If wireless marketing sounds familiar, that's because they're the people that bring us the Cherokee radio line. ©CBWI
Big Bust At Consumer Electronic Show
I don't have many details yet but there was a major bust of manufacturers and distributors of export equipment. 'Me owner of RCI and the owner of CTE international along with some distributors were rounded up on charges of fraudulent customs records.
This seems to be a continuation of an investigation that's been going on for about a year or more. Last year one of the major CB distributors was busted, their illegal inventory was confiscated, the owner was thrown in jail and a Grand Jury was called.
It was rumored then the owner was going to jail time, but now the rumor is that he will have to pay a hefty fine in the order of 1 million. Both the owners of RCI and CTE are still in jail. They are being held without bail because they aren't US citizens and as the story goes, the government is afraid they will flee the country. The others are being held on $250,000.00 bail each.
My gut feeling is that this isn't the end of this. I know of one manufacturer that was about to bring a new product into the country. This news has halted that deal and fast! It's equipment that comes into the country that's illegal in the box, e.g., non FCC approved CB radios and linear amplifiers.
If they're found guilty there will be big fines and jail time at stake here. This could impact our hobby immensely. A source told me that this has the potential of putting RCI out of business in the US. I'll keep you informed as the news comes in. ©CBWI
Bob's CB Has Opened
I thank everyone for their patients during this time of relocating. I'm sorry the newsletter has been so late. Reopening the store has taken many hours of work and it's set my schedule on its ear. I know many of you will be interested in a price list or catalog but it will be a while before time permits me to get it together.
I will include prices of new and popular products in the newsletter as space permits. The chipswitches are on order and I expect them in soon and Wilsons are in stock! Below is a small list of products you may be interested in http://www.bobscb.com/
|Chipswitch $49.95||Astatic EchoMax 2000 $139.95|
|Chipswitch Socket $11.95||Astatic 1104 Base Mic $69.95|
|NorthStar DX330HL $229.95||Mongoose AM Mobile $149.95|
|NorthStar DX440HL $269.95||Antron 305 Base Antenna $89.95|
|NorthStar DX880HL $399.95||Solarcon A-99 $59.95|
|Uniden PCI22 Chan. Kit $19.95||GPKI Ground Plane Kit $39.95|
NOTE: At the time of reprint some of the items are no longer available also the prices may have changed. Check Bob's CB web site. BobsCB.com