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Ham Nation Pine Board Project discussion

Discussion in 'Homebrew and Kit Projects' started by KD8YQC, Mar 25, 2017.

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  1. KE4OH

    KE4OH Ham Member QRZ Page

    Lots of things unique about Mr. Rice's VFO that Millen produced. Not the least of which is the mechanical design. I've had mine since my novice days in the late 70s. I recapped it last year. I was sad to do it because the factory wiring and soldering were absolutely beautiful. I gave it my very best and I think I did a credible repair. But the original constructors did a marvelous job.

    Mine still has the original "curtain burner" power cord with resistance built in to power the series-string tube heaters. That thing gives me the willies! That is the only reason I don't use this VFO very often. It is slated for replacement soon. I have a nice metal box that will house a cement replacement resistor and will route the 3 wires to the VFO - Hot, hot with series resistance, and neutral.

    That old VFO works very well, indeed.

    Sorry, I seem to have hijacked this thread!! I will mute now ...
  2. K9JWP

    K9JWP XML Subscriber QRZ Page

    I have little experience using the AM mode and none with VFO's, TxRx switches, etc. I have one HF rig and do not want to use it for my receiver when I transmit using the pine board. I am hoping to use a Grundig shortwave receiver instead and believe I need to use some configuration of a TxRx relay.

    1. Will grounding the Grundig antenna during transmit suffice?
    2. What will happen if I open circuit the pine board transmitter antenna port when receiving; should I ground the transmitter output through 50 ohms?

    Thank you in advance for any advice - Jim
  3. K9JWP

    K9JWP XML Subscriber QRZ Page

    I have completed the transmitter. Using an o-scope and 50 ohm dummy load, I have verified frequency output using the 7290 and 3885 kHz crystals. I can observe microphone modulation on the scope and can receive the signal on my shortwave receiver.

    Using the MFJ-813 QRP wattmeter, I measured approximately 0.25-0.30 watts, un-modulated carrier. Using the o-scope, I measured 11.4 volts peak-to-peak using the 50 ohm dummy load. The voltage measurement seems to support the MFJ.

    I am attempting to verify correct operation of the transmitter. Can anyone tell me if the 0.30 watts un-modulated carrier is indicative of the 1-2 watts (PEP?) I believe was stated by Bob Heil on Ham Nation?
  4. K9EID

    K9EID Ham Member QRZ Page

  5. K9EID

    K9EID Ham Member QRZ Page

    Certainly not a problem. Nice of you to stop by the Pine Board Project and only hope you have been following it
    on the Wednesday night Ham Nation shwos. If you woudl like to gt up to speed quickly, please visit
    all the way to the bottom where the entire PBP is posted - all of the great drwaings, schematics and the the videos of just
    the segments so you do not have to page through the entire hour. All here for you. Hope you get your Millen VFO
    working. Millen did some very incredible things back in the 30's through the 40's. Stay in touch
  6. K9EID

    K9EID Ham Member QRZ Page

  7. K9EID

    K9EID Ham Member QRZ Page

    Hi Jim
    Thank you for your note here. PEP is figured by multiplying your carrier by four. One watt is 4 watts PEP of AM.
    If you have 150 volts on the plates of the 6V6 and 6AG7 you should be seeing right at one watt. What is your final
    coil? Perhaps that and the tuning condenser are not perfect. You should see more, Jim. I have a very easy 'mod'
    coming in the next couple of shows that will give of +300 - 320 Volts and puts the outptu to 4 or 5 watts. I am seeing
    right at 1 watt of carrier with 150 volts on the plates. Several that have their transmitters working are seeing the
    1 watt output with the 150 volts of B+. Stay at it. Stay in touch, Jim...... thanks, Bob
  8. K9EID

    K9EID Ham Member QRZ Page

  9. K9EID

    K9EID Ham Member QRZ Page

    Jim, II am workign on the antenna switching for the Pin Board trnasmitter and will have it ready net two shows.
    Hopefully could do something this Wednesday but we will have to see about the Houston disaster relief but will
    certainly do it the following week.

    You are correct that you would ground the antenna input to the Grundig. I will suggest to build an antenna switching
    relay that will turn on the B+, switch the antenna from receive to transmit and mute the receiver. The Grundig
    should work well, Jim.
  10. K9JWP

    K9JWP XML Subscriber QRZ Page

    I will be patient and wait to see your RxTx relay solution.

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