Command Technologies HF-2500 10m Mod needed "Need HELP"

Discussion in 'General Technical Questions and Answers' started by N2YCK, Jul 21, 2021.

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  1. N2YCK

    N2YCK Ham Member QRZ Page

    Hello, I'm N2YCK from Watts Electronics, I have bought a commander HF-2500 amp for testing and like to get directions on how to make it operate on 10m. I cant find any info online. I did call Pal-Star and they said they don't make the Amp anymore and don't have the info I'm looking for. Would Anyone have any info on this 10m mod? Thanks for any help that can be given.
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Have you tried contacting Pat Stein N8BRA? I guess he's retired but he may have the information.
  3. N2YCK

    N2YCK Ham Member QRZ Page

    Thank you, I tried finding a number or email with no luck. I even tried calling his neighbors and there numbers were bad. Doesn't look as he uses and might not be active ham. Has to be someone with the factory paperwork for mod.
  4. WA2CWA

    WA2CWA Ham Member QRZ Page

    You could search for early (with no 10 meters active) and late versions (with 10 meters active) manuals and compare the schematics for differences. Tedious but might work. I find it hard to believe that Palstar has no info on it somewhere in their files. Supposedly, to get the 10 meter modification after you bought the amp, you had to contact them.
    Or, send him a query via snail mail and include a SASE.
    Last edited: Jul 22, 2021
  5. W1NB

    W1NB XML Subscriber QRZ Page

    I don’t have, nor have I ever worked on, a Commander 2500 but solely based on the limited info in the user manual schematic, it would appear that you possibly need to do two primary things:

    1) Connect the plate tuning capacitor to the 10 meter terminal on the wafer switch.
    2) Determine the best location for the 10 meter tap on L2 and connect it to the 10 meter terminal on the wafer switch.
    3) Construct and install a tuned input circuit.

    #1 and #2 should be pretty easy. You might even be able to find someone who owns one with 10 meters installed that will take a picture of L2 and send it to you. That’ll show you where to place the tap. If the existing band selection wafer switch does not have the open position, you’ll have to source a replacement. Check the existing switch to see if the position exists but a stop has been installed to prohibit the operator from selecting it.

    #3 could be a bit more of a challenge and could require some trial and error. Based on the schematic it’s made up of two inductors, one fixed capacitor and one 20-140 pF tunable capacitor, plus a relay and protection diode. You’ll have to construct the coils and acquire the capacitors and relay. I would start by examining the 20 meter circuit, the refer to the schematic section below for 10 meter values. I don’t know how they are constructed but I would assume, given they had provided upgrade kits, the components are constructed on a PC board. Just construct your board to look like the others.

    It looks like the original Command and the Palstar version might be slightly different. You’ll want to be sure you are referencing the correct schematic. E1846BF1-5341-46EA-8074-1B4617C6AC9F.png
    Last edited: Jul 22, 2021
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I've never had that amp, but did find several "internet" discussion stating, "I won't tell you how easy it was to modify for 10/12 meters," seemingly implying it's something really easy and not involving mechanical work.

    Pat owned Command Technologies when the amp was made and likely knows off the top of his head, if he can be contacted.
    N2YCK likes this.
  7. N2YCK

    N2YCK Ham Member QRZ Page

    thanks you
  8. N2YCK

    N2YCK Ham Member QRZ Page

    ok thanks, If I cant figure this out, Ill have a guy pick this up and look at it, also give him the info and schematic you game me, thanks you.

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