[Elecraft] K3/100 Voltage Drop when transmitting

[donovanf at starpower.net]

Poor regulation is a common failure mode with Astron linear power 
supplies. The problem is equally likely to be either in the power supply 
section or in the regulator section. 


There's an excellent troubleshooting and repair procedure here: 


http://www.repeater-builder.com/astron/astron-repair/astron-repair.html 


73 
Frank 
W3LPL 


----- Original Message -----

From: "James Walker" <jimmy.walker at outlook.com> 
To: donwilh at embarqmail.com 
Cc: donovanf at starpower.net, elecraft at mailman.qth.net 
Sent: Monday, February 25, 2019 7:35:49 PM 
Subject: Re: [Elecraft] K3/100 Voltage Drop when transmitting 

Thanks Don. I’m sure the problem is with with the Astron as you suggest. I’ll try your suggestions when I’m back at home in “shop mode,” 

Jimmy 

> On Feb 25, 2019, at 2:30 PM, Don Wilhelm <donwilh at embarqmail.com> wrote: 
> 
> Jimmy, 
> 
> Astron power supplies have a nasty habit of having loose wiring terminals. They use only pressure to hold the ring terminals on the inside to the terminal bolts. 
> If you can detect even a slight rotation of the bolt when tightening terminals on the outside, remove the covers and tighten those bolts from the inside. 
> 
> The other problem is improperly assembled APP connectors. If you look straight into the end of the connector, if you can see the tip of 2 blades in either side, give the contact blade an extra push from the wire side until the contact blade locks over the locking tab. 
> That is also a cause of APP connectors which tend to pull out with very little tension. 
> 
> 73, 
> Don W3FPR 
> 
> On 2/25/2019 2:12 PM, James Walker wrote: 
>> I have a K3 that behaves similarly to what Mike described. I switched from an Astron 25 amp (15 years or more old) power supply to a switching power supply. Problem solved. One would think the problem was my Astron power supply, but I don’t see any such power drop when I use my Astron with other 100 watt rigs. Very strange. 
>> Jimmy Walker, WA4ILO 
>> Macon, GA