Ham Nation Pine Board Project discussion

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

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  1. KA7FTP

    KA7FTP Ham Member QRZ Page

    I've been licensed since the mid 70's. Ironically I've always existed in transceiver land. (HW16, HW9, 764PRO, KX3, etc) I've never had a rig that used an external TR switch. I asked the question out of concern with protection of the solid state front ends. For a receiver I will be using the KX3 or 764PRO. Since a knife switch does not ground the antenna on the receiver, which I assume is good?, I will need a fast acting TR switch.

  2. VE3LYX

    VE3LYX Ham Member QRZ Page

    Ok. I have two transceivers as well. (No 19 WS and TS830S KNWD). Much handier for sure. My SS rx's have a standby position. I always figured that was enuf. I run a lot of tube rigs in the shack where the knife switch is Although my two Solid State rxs are there as well.
  3. KE4OH

    KE4OH Ham Member QRZ Page

    T/R switch is pretty easy to do. Get a 4PDT 120v relay and a toggle switch. Decent relays are cheap on Amazon, BTW. Toggle switch energizes the relay.

    1 pole switches the antenna
    1 pole grounds the RX antenna connection
    1 pole mutes the RX (assuming your RX has muting terminals)
    1 pole turns on your VFO, if you're using one and don't want to key it
  4. KD8YQC

    KD8YQC Ham Member QRZ Page

    For the power supply, two 20mF@450v capacitors are listed for the power supply and to get them from tubesandmore. They only carry that specification in an expensive multisection capacitor (part numbers 010217 and 001506). They do have some that are close but not to those exact specs.
    My question is which substitution would be appropriate? More capacitance or more voltage?
    They have 20mF@500v (part numbers C-SA20-500 and C-ET20-500-JJ).
    They have 22mF@450v (part number C-ET22-450)
  5. KE0EFX

    KE0EFX Ham Member QRZ Page

    Bob Heil has since changed the cap specs and I don't know what he changed to. He simply stated that he changed them and the resistor after he saw how the power supply performed under load.
    I've already got the power supply built to the "original" schematic, so to speak, and I used the 22mF@450.
  6. VE3LYX

    VE3LYX Ham Member QRZ Page

    I didn't build it like him. It doesnt matter Anything from 20ufd to 100ufd will work as long as voltge is sufficent. (450vto500V approx) He is trying to kill hum. Each resistor cap you had helps big time as I am sureU already know. I would use a lot lower value resistors because otherwise voltage drops and the rig works good at 250 volts instead of 150v. Treat the schematic as a guide but worry not. In fact my resistors are under 200 ohms. I did put a bleeder resistor across the output as well. 480K ohms
  7. KE0EFX

    KE0EFX Ham Member QRZ Page

    I'm glad you said that. I was confused why Heil would want the voltage at around 150v as every pre-amp circuit schematic I had looked at all wanted 250-300 volts for the 12ax7 that he's using.
  8. VE3LYX

    VE3LYX Ham Member QRZ Page

    We are thinking along the same lines. It works fine anyway. The basic design of the whole rig is remarkably good. Mod percentage appears quite good although I dont have a real good way of checking. XYL on a Rx some ways away said it sounded good. I ran the Preamp, mod side from before the choke and the TX osc from after so the Audio mod section would have slightly more then the rf stage giving it a bit more room for modulation and a slight advantage. I have been led to believe that is good design but really I am only guessing. Anyway it works and I am happy.
  9. VA7EDU

    VA7EDU Ham Member

    I found finding things a bit hard but I found this part: C-SA20-500 that is the 20uF 500V cap for
    $12.95 each so a bit better. I found if I googled the part then looked for a reference to Antique Electronic Supply I found them. The other capacitor was C-ET47-500-JJ for $5.95 each. Always assuming I did get it right. In any as elsewhere noted I don't think the actual capacitance values are super important in the power supply. The 47uF may be as it's noted as especially good for music amps and I am guessing is in the pre-amp?
  10. VE3LYX

    VE3LYX Ham Member QRZ Page

    I had bought 40 100 uf 450 volts from "mrs wong". Best thing I have done in a long time. I use them freely. At that value I always use an input resisitor to limit current inrush but they are good . Cost less he $20 for the whole box. Normally I buy from The Tube Store here in Hamilton On. They handle Spraque etc as well as almost any tube in current production and their service is wonderful.

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