How to Use a Freq Counter for Readout on Analog Radio

Discussion in 'General Technical Questions and Answers' started by KI5GKD, Dec 27, 2019.

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  1. KI5GKD

    KI5GKD Ham Member QRZ Page

    Hi,

    I have a very good running Kenwood TS-450SE that is quickly growing to be my favorite but I do miss the digital readout. I have a couple of Freq Counters (HP 5315A and Leader LDC 822) and I am thinking there must be some way of hooking one of them into the radio to display frequency that will not upset the circuit.

    73,
     
  2. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    You need to find a way to tap off the VFO, and then add or subtract that frequency to get the "real" transmitted frequency. Every rig will be different
     
    WB5YUZ likes this.
  3. KM3F

    KM3F Ham Member QRZ Page

    Frequency displays are normally from the VFO and mixed with a fixed frequency to arrive at the output frequency.
    The dial is not a direct readout, for example on SSB or CW when there is no output, not keyed up when keyed up and talking.
    Only time is on AM, FM or key down on CW.
    You would have to sample the VFO and build a stable Oscillator and mixer to feed the counter and calibrate the frequency to match the out put of the transmitter.

    Not quite the same but imagine using a Transverter driven by a radio to some VHF or UHF band.
    The radio has to be set on frequency and be stable, the Transverter has to be set on frequency and be stable and the output of the station has to be measured with an accurate and stable counter.
    This is if one cares!
    I have to do this using a Kenwood TS 2000, Transverter and a dedicated counter for the 222 band and all mode use as well as FM repeater use where split frequency and PL tones are used.
    On the Kenwood there is a menu to set the dial display for direct frequency read out but the whole system has to be calibrated or it would be way off..
    How the display is set, the menu allows 'keying in' the Transverter output frequency (after the system has been hot calibrated). Since the Transverter is driven from the 10m band the display is changed to follow 10m VFO changes but displays it in 222 band frequency movement. The frequency begins at 28.200 up. All that is changed is to 220. 200 and it follows perfectly right up the band and outside to get to 225.000.
    The radio has to tune up into the 30 MHz range to >>hear<< the repeaters but transmits down in band because all repeaters have a 'negative' 1.6 MHz split inputs.
    .
    You would not do this much but build a stable oscillator and calibrate all systems to be accurate.
    If you don't be accurate you will be hounded for being off frequency just relying on the counter.
    Then there would be no use in having the setup.
    A lot of wind! but trying to illustrate what you need to be a where of.
    Good luck.
     
  4. WA7PRC

    WA7PRC Ham Member QRZ Page

    Um... the TS-450S already has a digital frequency display. If you want accuracy, you would do something to the non-stabilized 20 MHz reference oscillator. It can be replaced w/ the discontinued (and pricey) SO-2 TCXO, or one of several other aftermarket choices.

    I bought an interface PCB kit (http://www.ebay.com/itm/123992844811) that drops in place of the SO-2 and is intended to use an external 10 MHz reference:
    [​IMG]
    Some UK hams developed it to use a TS450/690/850/870/950 w/ a GPS disciplined oscillator as a 28 MHz IF at ╬╝wave frequencies. I found a Rubidium source for cheep. :)

    Another fellow adapted a VCTXO. IMO, the niftiest idea (from Damon @KF5CQW) was to affix a PTC thermistor to the rig's reference oscillator crystal, to stabilize the crystal temperature at slightly above ambient. That makes it sort-of a "poor man's OCXO". Or, you could just keep adjusting the rig's drifty crystal oscillator. :)
     
    W7UUU and K7TRF like this.
  5. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Yeah, something is not adding up.

    I don't recall a rig from Kenwood with the designation TS-450SE. There's the TS-450S that already has a digital frequency display as Bryan posted above. If you're struggling with display accuracy then the TCXO option he presented is a good way to go.

    Are you thinking of a Kenwood TS-520SE? That's a rig Kenwood produced that lacks a digital frequency readout though it does support Kenwood's DG-5 display unit. There are also aftermarket digital display units available for that rig like this: https://www.ebay.com/itm/Kenwood-TS...ounter-Display-HF-SSB-HAM-Radio-/202352612193

    You can run a standard frequency counter on the TS-520SE's DG-5 output but as posted above it won't directly display operating frequency and you'll have to do some math which varies by band to determine operating frequency from the displayed counter frequency. That process is described here: http://www.radioboatanchor.com/blog/add-a-digital-display-to-your-kenwood-ts-520s-transceiver

    So what rig are you talking about?
     
  6. KI5GKD

    KI5GKD Ham Member QRZ Page

    Oops! That is what I get for creating a post when I should have been sleeping! I can't edit the original post but the radio in question is a Kenwood TS-520SE!
     
  7. KI5GKD

    KI5GKD Ham Member QRZ Page

    K7TRF - Thanks for the link to the radioboatanchor page, I can use that procedure to check mine. I have ordered a bare board and other parts to build one of the emulators on http://www.kv6o.com/wordpress/projects/kenwood-dg5-emulator/ . In the mean time I can use a freq counter to check mine. The only reason this has concerned me is that after "calibrating" the vernier with the built-in marker I find that more often than not I am half way between "marks" when in a QSO. I find it hard to believe that everybody else has a VFO that is "off" so it must be me.
     
    KD2ACO likes this.
  8. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    GKD:

    You are NOT required, by any regulations, etc., to transmit on any specific frequency. The only requirement is that your signal is confined within the frequency segment allowed to your license class. Frankly, the operator who calls CQ "sets" the frequency and, no matter what the frequency readout shows, anyone who calls on a different frequency is the one who is "off frequency".

    That is, the frequency, in the kHz position, does NOT have to end in 0.0 or 5.0. A lot of newcomers, because they have come from operation using FM on the 2-meter or 70 cm band, believe that such is a requirement. The truth be known, when operating using FM, the transmitting frequency doesn't have to be all that close unlike when operating using SSB. Quite often, the transmitting frequency will be as much as 2, even 3, kHz away from what is shown on the unit. This doesn't really affect the reception because of the wide bandwidth of the receiver.

    Also, many digital readouts are not all that accurate. The reference oscillator can, and usually does, drift and that causes the actual frequency to be different from what the readout shows. I have heard various operators stating on the "exact" frequency on which they are transmitting down to at least the nearest 10 Hz, sometimes even to the nearest Hz. However, when checking the actual frequency using something like a well calibrated service monitor, what the operator is "claiming" to be the frequency can be at least a kHz, even more, away from the the well calibrated instrument is showing.

    There are still a goodly number of units with analog dials still being used by amateur radio operators. Depending on the unit, the dial accuracy can be as close as 1 kHz (i.e. Collins S-Line, Heath SB-Line) or less accurate (i.e. Heath HW-100 / HW-101).

    Although I do have equipment that came with digital readouts, what I use most of the time is my Collins 75S-3A receiver and 32S-3 transmitter. On SSB, I control the transmitter frequency using the receiver. This equipment has an analog dial. However, I have added a digital readout to the 75S-3A that is accurate to, at least, the nearest 10 Hz and I do keep the reference oscillator calibrated to WWV. When calling CQ, I look for an opening that will not cause interference to nearby QSOs and do not worry that the frequency does not end in 0.0 or 5.0 kHz. Often, the frequency can end in something like 14.187.350 MHz. If someone calls me and tells me that I am "off frequency", I use the occasion as a "teaching moment" to inform that person about how things really work in the amateur radio realm!

    Basically, don't worry about what the frequency dial shows. So long as your transmitted signal is within the frequency segment allowed to your license class, your operation is completely legal and you definitely do NOT have to transmit on a frequency ending in 0.0 or 5.0 kHz!

    Glen, K9STH
     
    KK4NSF, WB5YUZ, WA7PRC and 2 others like this.
  9. KV6O

    KV6O Ham Member QRZ Page

    I designed and built a DG-5 emulator, based on the Arduino platform - https://www.kv6o.com/wordpress/projects/kenwood-dg5-emulator/

    I sell the PCB if you want to build one, I've sold several hundred worldwide over the past few years. It's not a kit - but there is a BOM and nothing is too difficult to source.



    There's a LCD version, an LED version (true to the DG-5), and a Nixie tube version!
     
    WA7PRC, W6KCS, KD2ACO and 1 other person like this.
  10. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    That readout is nifty! I want a Nixie one just because. :p

    The calibrator adjustment is easy to verify and calibrate by zero beating it to WWV as outlined in section 6.12 of the user manual.
     

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