Hi Louis,
Thanks for the suggestion. I didn't realize
dropping the rear panel was that easy. I hope I
don't have to go through this again, hi!
And, I did get one of your PS boards for the
future, it is a really nice product.
73 Bill N4LG
At 09:25 AM 4/11/2025, Louis Parascondola via groups.io wrote:
>When you want to get to the power supply on
>these amps you don?�?t remove anything on the RF
>deck.? The way to get to the PS is to loosen the
>set screws on the band switch and variable
>caps.? Remove wires from the terminal strip for
>the fan, drop the rear panel, unsolder the coax
>from the balun or at the relay.? Remove wires
>from terminal strip in the back.? Flip amp over
>on side and remove the screws holding the entire
>RF chassis.? Slide the whole RF deck out.? Flip
>it over on the bench and work on it from the
>bottom.? Sounds like a lot but I?�?m comparison
>it?�?s simple.? Since I?�?ve done it quite a few
>times I?�?m down to about 20-30 minutes to yank
>the deck out.? I have a replacement board to
>slap back in fully populated.? Most of the time
>the PC board is scorched and the traces lift off
>the board.? The board is ruined.? Cheap board
>.? Newer boards have masking and traces don?�?t
>lift.? Original carbon resistor change value and
>the HV meter reads low.
>
>
><>Sent
>from the all new AOL app for iOS
>
>On Friday, April 11, 2025, 9:06 AM, Bill Cotter,
>N4LG via groups.io <n4lg@...> wrote:
>
>Justin,
>
>I have a couple of HF-2500 amplifiers I've used for many years and
>experienced the same failure of the meter lamps. The earlier
>HF-2500 (single meter) has two bulbs and the later (two meter) has
>four. I put up with no lamps for sometime and then just gave in to
>fixing the problem when another issue cropped up.
>
>I noticed that the plate voltage indicated on the front panel meter
>of the HF-2500 (dual meter) seemed quite low, and did not match the
>voltage read with a HV probe on the anodes of the PA tubes by over
>500VDC. I decided to fix it, and replace the three meter lamps that
>were not lit. At the time I did not realize what a tall-order
>fixing the HV meter would be.
>
>Lamps first, I replaced the four incandescent lamps with 3800K
>Bright-Warm-White LEDs from a pinball supply company. These are in
>a #47 lamp form factor and are commonly used to replace lamps in
>boatanchor gear with 6.3VAC on the lamp. The current draw was
>something like 25mA each and I wired each meter pair in series. I
>also strapped a .001uf disc across each lamp to keep any RF out of
>the LED.
>
>There is also a published mod to the metering board where you
>replace the 7812 three terminal 12VDC 1A regulator with a 78S12 2A
>regulator. It solves the marginal current supply issue.
>
>The real pain was fixing the HV meter. As you may already know, the
>HV PS board is located under the RF deck. Nearly every part in the
>tank circuit must be removed to access the HV power supply board,
>as well as the front panel and more. It requires all this removal
>of "stuff" to take out a plate under the RF deck components that
>the HV board is mounted on.
>
>When I finally got the HV board out I found that the series
>resistors for the meter had gone way up in value. This probably was
>due to the dissipation in the three marginal wattage resistors, and
>the heat from all the bleeder resistors in the confined space. The
>air flow from the fan has about half of the air going to the
>right-hand tube closest to the fan, and the second half of the air
>passes through the HV compartment before it get to the left tube.
>So the left tube runs at a higher temperature. Go figure.
>
>While I was in the HV compartment I replaced all the filter
>capacitors with 105C types and replaced all the bleeder resistors
>and metering resistors with higher dissipation parts. I left the
>diodes as-is. Once reassembled, it worked great and the HV meter
>read correctly.
>
>After all this work I saw an ad from Palstar who apparently bought
>the Commander line and did a lot of upgrades on the already great
>amplifier. One significant change they made was to install a
>"door-plate" on the bottom of the RF deck to make easy access to
>the PS circuit board. If I ever have to do this again, I will cut a
>door in the bottom, hi!
>
>73 Bill N4LG
>
>
>At 03:24 AM 4/11/2025, KG2RG via groups.io wrote:
> >[]
> >[]
> >[]
> >[]
> >[]
> >[]
> >[]
> >[]
> >[]
> >[]
> >[]
> >
> >Hello,
> >I have a Commander HF 2500. Have not had it to long. When I got
> >it, only 1 of the 4 meter bulbs was working. After about 3 month,
> >the bulb went dark.
> >I believe there is a 12V 1A regulator that
> >supplies the meter bulbs and the relay. I read the pulls are
> >Festoon type and need to be no more the 0.08A each so to not
> >exceed max current and cause the relay to no key. I finally got in
> >there and they are not the fuse looking type bulbs. They are
> >little bulbs with with short leads soldered to the meter board.
> >
> >i finally got in there because I had another Issue with the
> >standby switch. I think the standby switch was intermittent and a
> >relay was not keying sometimes. I started noticing the problem
> >when I would first turn on the amplifier after the short warm-up.,
> >I placed the standby switch into operate and the amp would not
> >key. At first, I thought this issue may have been the regulator or
> >something else, but I started to notice the symptoms would often
> >happen after using the standby switch. I originally planned to
> >bypass the switch and see if the problem went away and then I
> >could replace the standby rocker switch. But when I got in there,
> >I noticed there was another set of poles that were vacant and
> >likely never used so I decided to utilize it those and see how
> >things went. I cleaned all of the contacts and the plugs on the
> >wire wires with deoxIt, And then plugged the wires onto the never
> >used terminals on the other pole. So far it's been great for the
> >past 24 hours. I'll give it some time, but if the problem comes
> >back, then I'll try bypassing it and if the problem still persist
> >during bypass, I'll look to see other possible causes but so far
> >things are good and my fingers are crossed.
> >
> >after messing around with the standby switch, I pulled the
> >metering board out and surprise, it was not the fuse type bulbs.
> >These bulbs had short leads soldered to the meter board.
> >
> >does anyone have a recommended replacement bulb suggestion? They
> >likely need to be 12VDC at 0.08A. I should've used my caliber to
> >measure the size so I'm not sure what size and what type of bulb
> >or where I can source replacements. Any help would Be very
> >appreciated!
> >
> >kG2RG
> >
> >
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