Thanks for the kind offer Mark,
But, I took the amp apart before replacing diodes.
I found bad solder connections and was able to reproduce the issue with
the amp sitting undriven, on my kitchen counter! I used it last evening
and earlier today in the French DX contest and the Winter Field Day
exercise-and it worked FB.
Regards to all.
Art
On 1/27/19 3:28 PM, Mark Schoonover wrote:
> Art,
>
> Take a look at 1N5408 diodes. I'm using these in a desktop kilowatt
> project. If they'll work for you send me sase and I'll send you what
> you need. I got a deal on a bulk purchase.
>
> 73! Mark KA6WKE
>
> Website: https://www.ka6wke.net
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> Author: 4NEC2 The Definitive Guide
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>
> On Sun, Jan 27, 2019, 10:28 Art <ky1k@myfairpoint.net
> <mailto:ky1k@myfairpoint.net> wrote:
>
> Hi All,
>
> When I joined the list, it was to get the skinny on solid state amps,
> little did I realize that my tube type amp would die and I'd be
> consulting the list for HV diode suggestions and vendors.
>
> But:
>
> I have a bottom end amp, 400 watts out, an AL84. The plate voltage
> dropped from just under 1kV (unloaded) to 600v and obviously the power
> output is way down. I assume I need new rectifiers.
>
> The manual says it uses 1kV @ 3 amp diodes, 8 of them total, in a full
> wave bridge rectifier configuration. The part number is AR-145, which
> isn't available, it's likely an Ameritron house number. The voltage
> rating of each diode seems marginal to me though (to me).
>
> I looked in Digikey and Mouser, they don't don't carry them.
>
> There are no equalizing caps or resistors, so I'd prefer to put in a
> single 4kV diode rather than deal with 2 diodes in each leg of the
> bridge. Barring that, I'd like to replace all 8 diodes with 2kV @
> 2 amp
> diodes.
>
> Are there any reputable vendors that sell these lower voltage
> diodes at
> a reasonable price, I would prefer NOT to use the online auction
> site::>
>
> Would appreciate any comments or suggestions.
>
> TY
>
> Art
>
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