yeasu ft 857d and ft 757gx can i use heath sb201 amp that has harback installed

Discussion in 'Amateur Radio Amplifiers' started by N8YUY, Aug 21, 2012.

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  1. N8YUY

    N8YUY Ham Member QRZ Page

    i have a new yeasu ft 857d and an older ft 757gx i needed some power and ran across a heathkit sb 201 and found it had the harback installed in late 2011 , my question is what do i need to use it with both radio's , separtely of course, thanks
     
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    It had which Harbach modification installed?
     
  3. 6Y5HN

    6Y5HN Ham Member QRZ Page

    It just needs the Harbach soft key mod (I am using a 757gxII with my 201 - works great). Connect an rca jumper from PTT on the 757 to he ant relay on amp. (after the harbach soft key mod is installed).
     
  4. N8YUY

    N8YUY Ham Member QRZ Page

    harbach softmod


    it has the harbach softmod, so the cable needs a phono plug on each end, i looked at the manual from heath and it said to use a phono to pl connector, evidently it was for an older rig. you made it so much simpler , i found plenty of sites telling me what i need as far as mods but not the cables or where to place them. as i stated before i also have a ft 857d and i see a linear cable on ebay around $25.00 i should order this as well if i am to use both rigs ?
     
  5. 6Y5HN

    6Y5HN Ham Member QRZ Page

    I am sorry I do not know much about the 857D but I imagine the manual should tell you where to pick up the transmit request on the CAT plug. A ham friend of mine uses the 857D CAT connection cable to plug into a "box" then came out with a phono to phono connection from the box to his SB220. (The 'box' was in place of the Harbach soft key mod which obviously does something similar as the Harbach board).
    Ultimately you have to have a phono plug on one end to utilize the antenna relay on the back of the 201. If a commercial cable is not available you will have to splice in a phone plug somewhere on the CAT cable end once you know which 2 wires carries the transmit information.
    Hope you get it sorted.
     
  6. W1QJ

    W1QJ Ham Member QRZ Page

    Harbach makes a "soft key" and a "soft start" Which do you have? BE SURE!
     
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page


    Exactly. That's why I asked which Harbach mod? Harbach offers several mods for this amp and only one has anything to do with keying it.

    When I work on these I don't even use the "Harbach mod," I just change the T-R relay to a 12Vdc low current relay, rectify the filament voltage to power it, and bring the wiring to the original keying jack. Costs $7.50 and the "mod" takes all of five minutes. Yes, I add a kickback diode across the relay coil: That costs five cents.:eek:

    I don't think the "soft start" mod is worth anything. My old original SB-200 which I built in the mid-70s never had this and still works fine, and never damaged the on/off switch. Seems the power transformer saturates before the switch rating is exceeded, so a switch failure is pretty rare.
     
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