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Re: [Amps] Tube amps are not a thing of the past

Subject: Re: [Amps] Tube amps are not a thing of the past
From: "Roger (K8RI)" <>
Date: Mon, 5 Jun 2017 16:48:05 -0400
List-post: <>
Add to that, the lack of knowledge in electronics, building, and the general age of "old timers", module / pallet replacement seems even more likely. Most of today's rigs use an output module.

It's probably going to mean a lot more work (and money) for those doing repair work. The old Collins and Hallicrafters rigs were relatively easy to repair and align. Very few of us have the knowledge and fairly expensive equipment to repair today's rigs so it's back to the factory, or authorized repair center with shipping costs as much, or more than the cost of repairing the old rigs.

As for device / pallet, replacement we are kinda getting back to requirements similar to bipolar substitution, although I think gain of the LDMOS will be less critical than with bipolars as long as it's sufficient (and fits). The Yaesu Quadra is an example of an amp that would be easy to upgrade and make much more rugged except for the device. Examples do exist with the 150 W devices being replaced with 300 W devices successfully, but the conversions were neither simple or straight forward and required a much more rugged Power Supply, making it a major rebuild.

73, Roger (K8RI)

On 6/5/2017 Monday 8:28 AM, Joe Subich, W4TV wrote:
On 6/5/2017 3:46 AM, Roger (K8RI) wrote:

The current crop of new devices is likely to be around much longer
than devices made just 10 years ago.
Given the trend to pallet based amplifiers, I doubt the device shelf
lifetime will be very long.  Instead, rather than replace an LDMOS
device on a pallet, the entire pallet (input transformer, bias,
output transformer, spreader, etc.) will be replaced in the event
of a device failure much like an entire tube is replaced in a tube

It may not matter what device (or devices) is used on a given pallet
so long as the I/O and form factor are the same and the new pallet
equals or exceeds the PO, compression point and IMD specs of the old.


   ... Joe, W4TV

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