Very frustrated with my HT / rooftop antenna. Any hints?

Discussion in 'General Technical Questions and Answers' started by KM6KCM, Jun 26, 2017.

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  1. WB4SPT

    WB4SPT Ham Member QRZ Page

    I'm generally a pro-Kenwood guy, at least for HF. So, I'm looking at the TH-D72A "specs". Sens and Select. are speced, IM is not even speced. The 92 page "in-depth" manual doesn't seem to cover any specs, only features. Coming from the commercial radio sector, my handhelds are speced at 80dB for IM. I don't expect over 70dB in a mid level ham radio, but not even a spec published? Shame on us. supply and demand.
    AI3V likes this.
  2. KM6KCM

    KM6KCM Ham Member QRZ Page

    Well, I can say that it's a significant step up from the Baofeng I had been using, and it's full-duplex for satellite work. ;-)
  3. KD4UPL

    KD4UPL Ham Member QRZ Page

    Have you used a meter to measure the SWR on your antenna? I would think that would be a good first step. You did a great job troubleshooting the programming problems. I almost always program my radios with the keypad, I feel it's very important for a ham radio operator to be able to actually operate the radio. This includes being able to program it in the field when a computer is not available.
    W4JFA likes this.
  4. N8EKT

    N8EKT Ham Member QRZ Page

    HTs were never designed for base use so they don't have the front end for it

    Today's radios are pretty much just police scanners that transmit so while interference sources have grown by a factor of ten, the radio front ends have gotten worse instead of better

    Your best solution would be to pick up a radio built in the 80s

    you can pick up a vintage Kenwood, ICOM, or Yaesu 25 watt mobile for under $100 these days and their front ends were FAR superior to anything on the market today

    You just have to find one that has PL code capabilty
  5. K9STH

    K9STH Ham Member QRZ Page


    Unfortunately, you are the victim of what is paramount among newcomers, to amateur radio, these days. Your first radio was a portable / handheld unit. Yes, they are inexpensive and they do cover at least 2-bands. Unfortunately, with the antennas that come with the units the range is pretty limited and, when a better antenna is attached, all sorts of receiving problems start. Of course, this is due to the "DC to daylight" frequency coverage of the receivers which means, basically, no filtering, no intermodulation rejection, and so forth.

    Handheld / portable units do have a place in amateur radio. However, NOT as the first unit for a newcomer. A much better choice is a mobile unit with an AC power supply for use at a fixed location. The mobile can be used in one's vehicle very easily and taken into the residence when desired. There are a LOT of used 2-meter and 2-meter / 70 cm band mobiles around often priced well under $100. I would definitely look for one. Of course, purchase it in person and make sure that it definitely works before laying out any money.

    Way too many newcomers start out with a portable / handheld unit and soon, because of all the problems plus, generally, only being able to hit a very few repeaters, they put the unit in a drawer and forget about amateur radio.

    I have had portable / handheld 2-meter FM units since the mid 1960s including, when I owned the Motorola reconditioned equipment center for the south-central United States, the latest, and greatest, Motorola units. But, those units were never my primary VHF / UHF FM unit. I have always had mobile and base station equipment that I use like over 99% of the time.

    Of course, I have equipment for operation from 160-meters through the 70 cm band including the 222 MHz band for modes including AM, SSB, CW, FM, and ATV. These days, the primary use that I have for any of my handheld units is to access the K5RWK repeater that is located less than a mile from my house. I have to be careful not to transmit on the input frequency when I am using my Bird 6154 dummy-load / wattmeter. There is enough leakage through equipment cabinets to hit that repeater even when running less than a watt output!

    Glen, K9STH
    N2EY likes this.
  6. AI3V

    AI3V Ham Member QRZ Page

    Substituting a DC to daylight mobile rig, for a DC to daylight ht rig is unlikely to make much of an improvement.

    And a blanket statement that no ht's have filters in the front end would also be incorrect.

    Look at something like the Moto ht1000, it has a varactor tuned preselector, fed from the vco line.

    Such a ht can be used next to the 100 watt Moto mobile repeater mounted in the trunk of the State patrol car.

    Of course a ht1000 costs about the same as 50 or so baofengs... :)

  7. K9STH

    K9STH Ham Member QRZ Page


    Fortunately, not all mobile units have the DC to daylight receivers, especially the older ones. Also, even those mobile units with the wide receivers do seem to have less problems than the handheld units.

    Now, I do not see the need for such wide frequency coverage for the equipment. Of course, I also was never one for using scanners, etc., to listen to frequencies outside of the amateur radio bands. Being that I have been employed, in one capacity or another, in the commercial two-way radio industry since I was a junior in college in 1965, I got my "fill" of such communications at work and definitely did not need to hear more when I was not working!

    When the Japanese started exporting amateur radio 2-meter and 70 cm FM transceivers into this country, there were a lot of designs that were very prone to having intermod. One thing that helped was to add a receiver "front end" from a Motorola Motrac / Mocom 70 between the antenna relay and the actual receiver circuitry. These Motorola units consisted of 5-loaded cavities and definitely helped improve the receiver performance. The front ends did reduce the sensitivity of the receiver a couple of dB. But, the elimination of all the intermod was well worth the slight loss in sensitivity.

    Although Motorola "front ends" are no where as near plentiful as in the "goode olde dayes", adding cavities, stubs, and so forth, can definitely improve the receiver performance. Of course, purchasing even used commercial cavities can be expensive. However, it is fairly easy to construct cavities and the cost of materials is very low.

    Glen, K9STH
  8. KA9JLM

    KA9JLM Ham Member QRZ Page

    You are not cool, Unless your radio has FM broadcast radio and a flashlight built in. :rolleyes:

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