Carl,
I appreciate your response. I could not find suitable 450v screw down
capacitors for less money than Harbach charges (including shipping).
I know you can get snap in caps for cheap but is it possible to solder
the snap in caps into the holes for screw down caps? If it is I may
go that route for my SB220.
In looking for an appropriate glitch resistors I found info
recommending the RCD Pulse rated resistors in a article from
NE7X/W8JI: http://ne7x.com/Henry_B_minus_resistor.htm
turns out that Ameritron just sent me the wrong part (non pulse rated)
so I can't use what they sent me anyway....Ameritron quality control
hihi
In the wirewound I see OHMITE L25J25R 25 OHM 25W around for <$10.
Anything else you would recommend?
I was thinking of mounting it right on the side of the Power supply
board B+ output. Is there any reason to put it inside the RF section?
I would think that you would want to avoid that?
73,
Zev N2WKS
On Thu, Jul 19, 2012 at 12:02 PM, Carl <km1h@jeremy.mv.com> wrote:
>
> ----- Original Message ----- From: "Zev Darack" <zevdarack@gmail.com>
> To: <amps@contesting.com>
> Sent: Tuesday, July 17, 2012 2:10 PM
> Subject: [Amps] Upgrades for LK500ZC?
>
>
>
>> I am in the process of upgrading an LK500ZC and am looking for
>> recommendations:
>>
>> I am currently working on the following:
>> 1. Installing the Harbach Power Supply
>
>
> I see absolutely no reason to waste money on that, just buy new caps from
> Ameritron
>
>
>
>> 2. Installing the Harbach Soft Start
>
>
> Most ZC's came with it but none of the earlier models had a problem
> withoutit....its just a useless frill in that amp that can cause its own
> problems.
>
>
>> 3. Replacing the Plate Choke which was rewound by someone with an
>> Ameritron Plate choke.
>
>
> They work well
>
>
>
>>
>> The amp also has a fuse between the Zener diode and the QSK board so I
>> am going to install a panel mount fuse holder for this.
>
>
> If the fuse blows you better go inside and find out why instead of drilling
> holes.
>
>
>
>> KM1H recommended I install Glitch protection.
>
>
> Yep
>
>
>
>> The current tubes are showing a blue color during transmit so I will
>> be replacing the tubes as well. Eventually one of the tubes flashes
>> over and causes the fuse on the zener diode to blow. The amp is
>> putting out over a KW so I think everything else is ok.
>>
>> Questions:
>> 1. Glitch protection: I plan to add 3 10 ohm RCD 175P-10R0-FBW
>> resistors in series in the B+ line.
>
>
> Whatever they are?
> Why not just one 20 Ohm 25W enamel wirewound?
>
>
>
> Looking for advice on where/how
>>
>> to mount this in the amp?
>
>
> Replace the small RFC at the base of the plate choke with the resistor.
>
>
>
>> 2. Recommended mounting location for the soft start in the amp?
>
>
>
> The factory one mounted above the power distribution board
>
>
>
>> 3. Is there anything else I should look at that could have caused the
>> tubes to go bad?
>
>
>
> Lack of use and regular gettering
>
>
>
>> 4. Are there any other recommended upgrades for this amp?
>
>
>
> The Ameritron choke will improve 160M output. Id measure the parasitic
> resistors and if out of spec replace with Ohmite OY type from Mouser.
> At the front wafer, right side support make sure there are no sharp edges on
> the 160M lug. Also paint the junction of the ceramic spacer, nylon washer,
> and wafer with an anti corona dope or something else to prevent an arc to
> that 160M contact.
>
> Carl
> KM1H
>
>
>
>>
>> Thanks es 73,
>> Zev N2WKS
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>>
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