Q.  I have an RCI-2950 running off an I-max2000 .Would a Receiver amp increase my listening capability to any extent?? Thank you., W. Carey

A. At 27 MHz a receiver preamplifier won't do anything but increase the background noise right along with the signal, so you don't really get
anywhere. Preamps don't really help reception on frequencies below at least 50-100 MHz. A better antenna is the answer.

Choice of Co-Ax Cable Impedances for Radio Use
    These standards were set many decades ago. 50 ohms provided the most efficient match for transmission through coaxial cable (current-carrying capacity versus loss in the cable), while video reception (voltage rather than current) efficiencies were better at 75 ohms.
    And there's another reason: A basic, half-wavelength, dipole antenna has a 75 ohm feed point impedance in free space; it's a little lower in typical terrestrial installations. Similarly, TV antennas with their multiple elements are closer to 75 ohms, and 300 ohm dipoles are easily matched with 4:1 balun transformers (300:75 ohms).

Q. I leave my DC adaptor for my new receiver plugged into the wall all the time.  The DC adaptor is hot even when my receiver is not attached.  Is the adaptor drawing electricity even though there is no receiver attached?  Should I unplug DC adaptors from the wall when not in use?  I have lots of gadgets with DC adaptors.

A. Nearly all AC adaptors are simply transformers with rectifier/filter circuits. Since a transformer is a collection of wire windings, when they are plugged into the wall they draw current. The current is low, but with time, they can burn out. I unplug all mine when not using equipment for long periods of time or charging batteries.

 

A. Amps are calculated by dividing watts by volts. In this case you would divide 0.040 watts (40 milliwatts) by 18 volts, giving you 0.002 amps
(2 milliamps).

Q.  What causes a scanner to " go deaf?" I have had a  couple of vhf/uhf do this.
     Could barely hear my HT standing next to it.  Mark

A.    It literally could be any number of things.  Desense, AGC lockup, CTCSS or DCS lockup, heat related problem (amp component breakdown), etc.  One thing that concerns me if you have been exposing your scanner to transmit RF that could also cause a premature death. This is especially so if you have your receive antennas co-located with your
transmit antennas.
 

Q.    How do I tell if a frequency is AM, WFM, NFM? Thanks in advance, Scott Bailey.

A.    Your question is not easy to answer.  For instance, in the HF radio spectrum just about anything goes. Above 30 MHz certain pieces of the spectrum has their mode of choice (but there are always caveats here as well).  There are some loose rules that radio hobbyist follow. For instance here are the highlights of the VHF/UHF spectrum assignments.

Q.    I have an interesting question regarding the use of an old DirecPC dish. Can it be used for receiving satellite signals, either audio or video, and what other equipment would be needed? I have an old DPC dish on my roof (thanks to a cable modem!) and am trying to find a use for it. B. Vallone Racine, WI.

A.    I'm afraid there's little you can do with it. The device is specifically for receiving a service that is no longer in its receiving bandpass, and its internal components are strictly for that digital service, so it can't be used as-is for any other service. The dish and feed horn could be used for any other service in the suitable microwave frequency range (12 GHz and up), but not the receiver circuitry without considerable modification. I'll forward this to Larry Van Horn who
is more on the cutting edge of satellite reception to see if he can add anything.

Q.    My cell phone is several years old, and as I'm searching for a replacement, I can't find any reviews or even any mention as to how well they actually work!  Only lists of bells and whistles and how pretty someone thinks they are. Since a cell phone is essentially a transceiver,  has there ever been any interest at MT in reviewing such devices from an radio point of view? Does every cell phone really transmit and receive with the same efficiency as every other?  If MT had a once-or-twice-a-year issue with such reviews, it might broaden your reader base? (Maybe this is an old idea to you, but it was a new one to me) anyway,
T. Harris

A.    Yes, since there are just a few prime chip makers, most cell phones made now are peas in a pod with a few variances such as accessory ports (data, antenna, etc.) and functions. Choose one based upon what you need it to do, not whether or not you think this inside electronics are better in one than another.

Q.    I am replacing a vintage VW bug.  Down through the years I have been very spoiled because this vehicle allowed me, to install a variety of mobile telephones,  scanners, CB and amateur transceivers and still have legroom for driver and front seat passenger. I know that room for communication equipment is a problem for public safety agencies the world over, but then they just buy bigger vehicles in which to install the gear that they need. Most of the vehicles that I have recently reviewed all seem to have a center console and provide little room for equipment installation. The Ford Ranger and the Toyota Hybrid are two exceptions that I have found and I know there must be more. 
         Bob, have you seen any survey for the current automotive market that focuses on floor and dash free areas? I am sure that I am not the first communication buff that has faced this problem.  This might turn into an annual MT feature.  "Bob Grove's Top Radio Friendly Automobiles of 2003" or the like. Any ideas?  G. Currivan

A.    Yes, the idea of compact consoles has really caught up with the automotive market; I have a Ford Explorer, and finding a spot for radios in there is a problem, too. I hate to drill holes in the dash, but that's about the only think left. Some folks make instrument clusters and put them in a box between the passenger and driver seats, and some mount them overhead, but it's a problem. No, I'm sure no one has done a study of vehicles to see what's available on the current market that's radio friendly! I'll send this on to our editor, Rachel Baughn, in case she's interested in suggesting the topic to one of our writers.

Q.    I need some advice. I am looking for an excellent portable scanner for fire  purposes. I will be scanning 46 MHz as well as 154 and UHF fire channels. What would you recommend. Money isn't the issue-hearing LOW band is!!  Billy

A.    All scanners have virtually identical sensitivity now days. The problem with the 46 MHz low band reception in scanners is the small, non-resonant antenna that comes with the radios. There are several considerations: 

(1) Plan on using a good, multiband, rooftop antenna for your reception. This would be the ANT-7 ScanTenna (nothing beats it) for a rooftop mount.

(2) For the car, you need something better than the conventional small whip. I'd recommend the AOR MA-500 mag-mount whip for mobile applications; it is our catalog #ANT-12. 

(3) So far as a whip to put on your hand-held to replace the original, I'd recommend the ANT-19 Austin Condor; that's our leading replacement rubber duckie for folks who want a better whip than what came with their radios. But it won't work nearly as well as the other two above.


Q.     I purchased a BC780 from you recently.  I paid you $349.95 plus shipping.  In several magazines including your Monitoring Times I have seen it advertised for less.  What is your policy for price  protection?  Should I expect you to match the lower price.  I saw it at  this lower price within a few day of the purchase. G. Warren

A.    No matter when and where you buy any product, you will find it selling, sooner or later, lower somewhere else. A company bases its resale price on many factors, including shipping charges and after-market support. We have many "bargain basement" competitors who are not full-time, respected dealers. They place ads, take orders, and when enough orders are on hand for them to make a purchase so they can take a discount, they finally order the products for their customers. These and other predatory-pricing dealers often have no after-market support, and if a customer is dissatisfied, they charge a substantial restocking fee. We have been in business for a quarter century, with our customers
returning because of trust and satisfaction with our service. We hope you will join that growing group. You do, of course, have the option of returning any Grove product within 15 days for a full refund less shipping, assuming the product and its packaging are in as-new condition.

A.M. Reception

 Q.   What would be a good radio for A.M. reception? R. Morey

 A.   The GE Super Radio is an excellent choice, but you may also need an accessory antenna, the Super Radio allows you attach an external antenna like a long wire or dipole via coaxial cable, but you can also get a Select-A-Tenna http://www.grove-ent.com/ANT21.html which gives enormous signal improvement just setting alongside your radio. It is a 12" loop antenna which can be frequency-adjusted for optimum reception on the station of your choice, then "focuses" that signal on the radio's internal ferrite-loop antenna without physical connection. If desired, you can also remote-locate the Select-A-Tenna and connect it to the Super Radio by coax cable.

Frequency Range

Q.    If there's nothing to hear above 960 MHz, why do so many newer scanners and wide-coverage receivers go up to 2000 MHz and higher?

A.    It's true that in our entire history, I don't remember a single logging being reported above 960 MHz. At those frequencies range is very limited, almost all communications are by data and voices have been digitized. There is a ham band near 1300 MHz that has clear speech and may be heard in large cities; the declining 1500 MHz INMARSAT downlinks still have some clear speech; the GOES weather satellite sends imaging at 1690 MHz; and some backbone repeater links for federal government agencies around 1700 MHz ("L Band") may still have some use (although we've never heard of any. 
      With such limited practicality, why are these ranges included on scanners? Marketing. If you see two scanners side by side of virtually identical performance, and one goes higher in frequency, which one would you buy? From a practical standpoint, if manufacturers would limit their upper frequency range to 960 MHz and improve selectivity and dynamic range, performance would improve and prices should drop.

Antennas

There are several factors that weigh in so far as the distance an antenna can hear, including:  

Height of the antenna; Presence of obstructions; Length and losses of the transmission line; Gain of the antenna; Direction in which a gain antenna is pointing; Frequency of the signal; Sensitivity of the receiver; Presence of interference Power of the transmitted signal; Bandwidth of the signal Solar effects (day/night, sunspots, flares); Weather and humidity; Electrical storm presence.  

That said, under normal circumstances, and using the non-directional AX12B with good coax, good locations and a good receiver, the following could be expected: (1) HF reception (under 30 MHz): Thousands of miles for broadcasters, two-way communicators. (2) VHF (30-300 MHz): Up to 100 miles for broadcasters and two-way communications. (3) UHF (300-500 MHz): Up to 75 miles. (4) Microwave (800-2000 MHz): 25-50 miles.  

Naturally, these are only approximations due to the numbers of variables pointed out above, but should give you an average expectation. Naturally, if you're looking for a simple, low-power device like a bug or cell phone, we're talking feet, not miles.  

RG-6/U is outdoor video cable, rated at 72 ohm impedance. It is intended for weak-signal reception (although it will easily take over 100 watts of RF for transmitting) and is much smaller than RG-8/U. However, it is 100% shielded and utilizes low-loss dielectric insulation, and it's intended for frequencies up through UHF. RG-8/U is made for 50 ohm systems, primarily for transmitting (that's why it has a larger center conductor) and is copper-braided shield. If you get the foam-dielectric, it has low loss, whereas the older, polyethylene insulation can be lossy. It is considerably more expensive than the RG-6/U, and connectors are more expensive, too. The actual line-loss characteristics of the RG-6/U and the RG-8/U are virtually identical. While the impedance is nearly 50% higher in the RG-6/U, the actual signal loss due to this mismatch is inconsequential. The smaller-diameter RG8/X or RG-8/M (smaller diameter than RG-8/U) works quite well. The reason Grove Enterprises recommends RG-6/U over RG-8/U in all our VHF/UHF scanner applications is that it is less expensive, smaller diameter, less rigid, no more lossy, and offers cheaper connectors and adaptors than the RG-8/U.  

A. The H900 is a superior active antenna and capable of performance at least equal to a 100 foot wire dipole, so if you're not hearing anything at shortwave, something is amiss. We occasionally get inquiries like this, and it almost always turns out to be an oversight in the installation. Sure it could be a rare defect, but take a look at these suggestions first:
(1) Measure the voltage at the antenna jack where the probe cable plugs in and make sure the voltage and the polarity are correct;
(2) If you are using adaptors, make sure they are correctly installed and making physical contact along the path.
(3) With an ohmmeter, be sure there are no shorts and that there is continuity in the cables. I live in South East Michigan about 40 miles west of Detroit, in fairly open country with no antenna restrictions other than me not risking my neck. I'm running a Grove Sky Wire about 20 feet off the ground in a straight, N-S direction, fed through about 100 feet of RG-58/U and a Grove TUN 4 inside my basement. I know that SW signals are directional and I want to receive short wave stations from around the globe. Sometimes reception is not at it's best.

A. Currently, reception is spotty since we have just passed the low ebb of the sunspot cycle. If all of your receivers experience the same poor reception, it has to be either the signal propagation or your antenna system. First I'd recommend you carefully inspect the entire antenna system--solder joints, coax connectors and adaptors, the coax itself (dogs and squirrels eat mine!). You might try measuring the resistance to the antenna this way: Disconnect the connector from your receiver and put an ohmmeter (high ohms) across the shell and center pin; you should see no reading (maybe very high resistance--many thousands of ohms--which would be OK, but could indicate moisture intrusion).  Next, clip a wired pair of alligators across the antenna center connector and make the same measurement as before at the receiver connector, but this time on low ohms. You should see the dead short--no more than a few ohms.

Q. Would you recommend re-orienting my current antenna, installing two Sky Wires, one N-S and one E-W, or running a newer antenna, such as the PAR 'End Fedz', your stock # ANT08? If so, what should be the orientation, or does it matter?

A. The PAR antenna is excellent, albeit more expensive than the Skywire which is a fine antenna. Whichever you choose, you could put it up at right angles to the first antenna (they can even cross without mutual interference). You could then use an antenna switch like the ones we carry to select the best antenna for a particular angle of arrival, or simply unscrew one antenna cable and attach the other. Even easier, you could erect a vertical antenna hung from a tree limb like our very popular FlexTenna model HVU; that's what I use, and it doesn't have to be rotated!

Q. I have a Scantenna on my roof supplied with 125 feet of Belden 9913 RG8/U coax but I would like to add a second antenna to boost my reception and thought that your Grove Omni-II VHF-UHF Receiving Antenna would be a good choice. I know there would only be a 3dB gain at most but if it does not work well enough I could always reverse the splitter and switch between the two antennas.  Does this sound like a good idea?  If not is there a better antenna to try or use for this?

A.  It's true that the best you would get would be 3 dB improvement on some frequencies, but there are really two problems here: (1) Since the Scantenna is a better antenna than the OMNI, there would rarely be even that much improvement, and (2) the signal degradation in other directions would mean you should rotate the array. So: I'd recommend a beam antenna, especially if most of the traffic is from one general direction--either the Scanner Beam or the Create. Both would provide better reception. But first, before you do anything else, I'd recommend you try a preamplifier to overcome the losses in the long transmission line. Although it would be best to put it up at the antenna, even mounted at the scanner end would be an improvement. If not, you can always send it back within 15 days as new for a refund except shipping.

Q. I live in central Florida near the gulf where reception of he AM band is terrible. I use a Kenwood R-2000 and a Sangean "Super 909 Radio" I have also the big Super GE Portable and other portables, including 400 PE Yacht boy.  I use a long wire antenna, about 150 feet long, with a   coax cable lead.  I have a lot of electrical interference in our house  when I tried an inside antenna amplifier, but the outside antenna is  relatively interference free. I considered buying the Icom R-75 from  your organization until I read the sleep time, beeps before the radio turns off, a very bad option for people like me who like to listen to the radio while going to sleep.  Question: 1. What is the best radio, old or new, for AM dxing? (preferably under $600)  2. Is there anything else I could do to improve my outside antenna, other than making it longer?  Sincerely,  J. Rakes

A. I was going to recommend the R75, but if the beep is intolerable and undefeatable (I don't know), then I guess you can try something else. The problem with other radios is, of course, they generally have a permanent attenuator in the MW band. To avoid interference, and outside antenna is mandatory. However, 150 feet is hardly necessary with today's sensitive receivers; I'd say that 25-65 feet would be plenty. I use the 24-foot Grove HVU Flex-Tenna hanging from a tree limb and get terrific reception. You could do the same with a simple wire hanging down, connected to the center conductor of the coax with the shield left unconnected at the antenna (but connected, of course, to the receiver). I recommend vertical because AM broadcast signals are often vertically polarized because of car antennas, and they are omni-directional as well, allowing reception 360 degrees.

Q. Is there such a thing as an outdoor spray paint type that would work on aluminum antenna elements (i.e. the Scantenna), without attenuating the signal? If so, would the same paint spec apply to transmitting antennas as receiving?
i.e. outdoor micro-FM antennas. Many thanks, K. Geurs

A. It's the pigment that causes the problem; unless you know it's a non-conductive material, you're better off with a clear acrylic.

Q. I live in SW Florida (Gulf side) and need your suggestions for an antenna for my ICOM R75 and Uniden 898t.  I did my home work on both units and now am working on the right antenna.  I live in a condo (first floor) which is made of stucco and concrete (hurricane safe) with a screened lanai.  I can mount antennas on the lanai (L15XW8XH12) and can "sneak" mount a wire antenna outside of the lanai, however, I would like to avoid doing this since we are lightning capital of the world.  I mainly listen to both units at night (9MEST to 1AM). ICOM:  I've been using a Slinky antenna (mounted inside) for the past month with ok results (I have nothing to compare it to).   I thought about hanging it outside on the lanai and run Heliax coax with a balun to the bedroom.

 I have considered a long wire on the lanai with a balun (ADP35) and Heliax feed line, the Par ANT08, and other antennas.  I read somewhere that you can take a long wire (75 ft for example) and run it along the outer edges of  the bedroom or lanai ceiling (outer diameter of the ceiling) as a big loop.  Uniden:  I have the stock whip antenna with ok results.  I clipped the slinky antenna and did not notice much improvement.  I considered a discone mounted on the lanai, yagi, and others found at various websites. AM/FM:  I use a C Crane Reflect Antenna mounted on the lanai for FM and a large (21X17) loop antenna for AM (Ultimate Am Antenna created by Carver and sold on Ebay by Jeff as a kit).  Both provide excellent results. Selecting an antenna seems to be more involved than selecting a receiver.  Any suggestion will be appreciated for the ICOM and Uniden.    Jim

A. Yes, antenna choice is very important. For shortwave (the ICOM) try to get 20-40 feet outside the building as far from the building as possible, high as practical, and away from electrical lines. Be sure to feed it with coaxial cable (any kind except RG-174/U); the heliax is a waste of money at shortwave. If cost is not a strong consideration, but size of the antenna is, then get the Skymatch H800 from the Grove catalog; it's terrific for shortwave reception;  http://www.grove-ent.com/ANT15.html  For the scanner, our OMNI-II is great for overall local reception, is unobtrusive outdoors, and will outperform the whip you're using; feed it with inexpensive RG-6/U as the ad suggests:  http://www.grove-ent.com/ANT5.html

Q. This is Ken Harland with Sea Tow Sebastian.  I have two of your scanner beam antennas that I use solely for marine vhf communications.  I would like to know if these antennas can be optimized for 150-160MHz.  My station license allows for 50 watt transmission capabilities but I prefer to use a standard marine radio that is 25 watts because it has a wireless mic along with other helpful features.  I've looked at various amps and can't seem to find a reasonable or cost effective solution to increase my signal strength, consequently have been looking at higher gain antennas and see that other directional models with higher gain simply have less elements than the Grove Scanner.  I realize their spacing and size is critical, but also understand that the Grove Scanner is a wide band antenna, thus could probably be simplified and optimized at the same time.  Any assistance you can provide would be greatly appreciated. regards, Ken

A. Since I'm the original designer of the Scanner Beam, I've had a lot of experience experimenting with it. For the 160 MHz marine radio band, you can first saw off the longest (rearmost) element since it's for low band.  Next, you can also saw off the smallest forward elements since they are for 800 MHz UHF. The main problem is the balun transformer which may or may not be good enough for handling 25 or so watts of transmit power; that balun is simply a TV receiving unit. I'm going to go to the basement workshop and try an experiment to see how much power it will take before saturating--and maybe cooking--the little toroid transformer in the balun.

Q. I've got an interest in one of your WINRADIO receiver cards (probably the WR-3150) but let me tell you what I'm trying to do and ask for your help. I'm outfitting a 43' sailboat for indefinite blue water cruising (private use only - no government association). Among all the other goodies and widgets I'm putting aboard (w/ luck, there'll even be a little room for food) I'd love to have DF gear so I have the option of electronic navigation as well as visual, GPS etc, for all those really remote islands that might only have an AM radio station and an airfield beacon.  So, I'm looking at a receiver frequency range of 500K to say 300M to cover just about any transmitter I might reasonably expect to encounter. I'm going to be running a very capable windows computer w/ XP and I'd prefer to have the DF capability integrated into it rather than a stand-alone machine. It appears the 3150 would have the freq range I'd want, but my problem will be the antenna if I want to DF as well as "just" receive.  There will be a gimbaled radar platform 1/2 way up the mast where something could be mounted hanging down.  There are stainless "long wires" (that hold up the mast) bow, stern and sides w/ the stern doubling as the SSB HF antenna. Along the sides of the deck, there are stainless lifeline stations about 30" tall that could be electrically isolated and possibly tied into some kind of antenna configuration. Well, that's the big picture - any creative ideas? Appreciate the help, L Winkler  

A. The main problem you are encountering is not the availability of systems that will do the job, but that there are different types of RDF antennas for different parts of the spectrum. For example, while a loop can be used successfully at low frequencies (not much higher than the AM broadcast band for dependability), An Adcock array is best at HF (up to about 30 MHz), and a pseudo-Doppler array at VHF/UHF. Thus, you could conceivably use the same receiver, but you'd have to be switching arrays. There are some low-cost receivers for marine use that cover the 200-400 kHz beacon band and AM broadcast band; these have the ferrite-rod antenna already mounted on top of the receivers; they work reasonably well for dead-heading. HF is a bit more difficult, since an Adcock is quite large (mine, for 7-30 MHz, is 5' wide with two 8' vertical elements, one on each end of the boom) and it has to be rotated. You can rotate it electronically with a goniometer, but such systems are hard to find. At VHF, you can use most any Doppler RDF which electronically rotates the antenna; I've used the Ramsey DDF-1 with great success, but it's limited to about a 2:1 frequency range. There are more exotic systems available that do everything but the wash and cook dinner, but they get into the bucks! For example, see our WiNRADiO WD3000 which uses that SR3150 receiver.

Q. I thought RG6-U coax was not as good nor compatible to use as antenna cable for scanners.  Is it also a good choice for transmitters in the 158.00MHz range? Thank you, Jim

A. This common misconception originated in the early days of scanner listening. Many misguided folks use long lengths of lossy RG-58/U coax for scanner reception (and VHF transmission) just because it has a 50 ohm impedance, convinced that coax of any other impedance simply won't work. The fact is that while a proper impedance match is desirable to avoid resistive losses through the inner dielectric (insulation) from high voltages which develop during a mismatch, very few antenna systems exactly match 50 ohms anyway, especially over wide frequency excursions. Although RG-6/U is 70 ohms, not 50 ohms, its low-loss characters tics more than make up for any theoretical impedance mismatch. If you substitute 100 feet of RG-6/U for RG-58/U in scanner monitoring above 30 MHz, I can guarantee you better reception, and the higher in frequency, the more the improvement. I use RG-6/U exclusively for my VHF/UHF monitoring, and use RG-58/U only for shortwave where its losses are not that severe.  Coaxial cable, by its very construction, is virtually immune to outside electrical interference. The best shielded coax is always the better choice, and RG-6/U is very well shielded. It also has less loss in its dielectric (inner insulation) than competitive cable types. So that's the long answer which could have been shorter--"Yes!" Coax can be run underground, through water, alongside power cables, near satellite dishes and other electronics equipment without picking up interference. Try to keep it as short as possible, however, to avoid resistive losses from the longer lengths.

Q. I installed it so that it runs east-west. I would like to improve its range and am wondering if I should purchase another PAR antenna and run it north-south. A. Yes; it is presently rejecting signals from east and west since those are off the ends. A second antenna at a right angle to the first will solve that. Q. If it would work, can I connect the 2 antennas together so that there is just a single connection to my radio? (My radio is a Grundig Satellit 800 that was purchased from you several years ago as a holiday gift for me.) A. No; it's likely that the phasing of the arrival of the signal on two antennas at two different times due to their separation could cause destructive interference on some frequencies. But you can certainly try it first and carefully tune around, comparing signal strengths with and without the tie. Q. Would having the 2 antennas cause signal overload? A. No more than one would, even if they are connected together. Q. Do you have a suggestion for a better/alternate method for increasing reception? A.. Mounting it vertically would give omni directional response. Q. Finally, as expected, I do get a lot of background static/noise on some stations. Is there something you recommend to boost the signal and reduce this noise? A. Nope, not without a beam which restricts noise from anywhere but the narrow path at the front.