[Amps] AL-1500 fan speed switching

[Alek Petkovic]

The AL-1500 does come with a chimney. It is glass. Yours may have been 
broken by a previous owner and never replaced.

I bought my AL-1500 second hand and the guy shipped it with the tube 
installed. Needless to say, it was a mess inside, when I got it and 
opened it up. The chimney was busted, as were the grid fingerstock 
contacts. The pins of the 8877 were all bent inwards at about 30 degrees.

I had an Eimac 8877 socket and chimney and so I used the fingers, 
spacers and teflon chimney. I successfully straightened the tube pins 
and the amp is running nicely to this day. I recently replaced the 
marginally rated hv filter caps.

Your tips for soundproofing and wire size upgrade are very good. I will 
try that with mine. While I have it open, I will perform W1QJ's hv 
safety mod as well.

73, Alek
VK6APK

On 8/11/2013 8:24 AM, Réjean Léveillé wrote:
> Hi Ricks
>
> If you looked the amplifier rear panel, there is a spare hole located below
> the main power K2 relay. I installed a small SPDT switch between medium and
> high speed. To extend the two brown wires each side of SPDT with the center
> for purple, see your instruction manual. I also added some sound proofing
> under the top cover and against both walls where is located the blower
> motor. Do Not put sound proofing material over the tube.
> Now what I could not understand why there is no chimney, I fabricated one
> with high temperature orange color silicon rubber sold at aircraft part
> supplier. The silicon sheet glued with high temperature silicon glue. Also I
> sealed all 4 tube box corners with high density tape. Now almost 100% air
> flow must get through the tube, this keeps the RF section cooler and also it
> cut down the fan noise vibration. The chimney end is about 1'' below the
> cover. In fact I always keep the fan speed to high speed.
>
> I bought it second hand with Eimac tube, it got less than 10 hours. The guy
> was too afraid to use it. I did full mods for HV section, 24v PS, vacuum
> relays, inrush current filament, double all wires size for HV input transfo
> and secondary 5v, chimney, added capacitors for 160m, operation LED,
> soft-key circuit. Now it looks closer to top end and commercial grade
> amplifier. At 1.5kw only 15-20ma Ig key down.
>
> 73, Rejean va2am
>
> -----Message d'origine-----
> De : Amps [mailto:amps-bounces at contesting.com] De la part de rick darwicki
> Envoyé : November 6, 2013 9:47 PM
> À : AMPS
> Objet : [Amps] AL-1500 fan speed switching
>
> Anyone have a clever way to add speed switching to an Ameritron, I.E have it
> run on low in STBY and med or high in OPR ?
>   
> I'm thinking at least automatically from the STBY/OPR switch for Low/Med
> with an option to kick it to High for RTTY contests.
>   
> Taking 30 screws out of the case is not a good option.
>   
> A three position switch on the back panel is probably easiest but would
> require getting up out of my chair hi hi 
>
> Thanks
>
>
> Rick, N6PE
> =======================================
> The only difference between a rut and a grave is the depth.
>
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-- 
 From sunny Binningup, Western Australia.

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