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

[Roger (K8RI)]

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
> amplifier.
>
> 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.
>
> 73,
>
>    ... Joe, W4TV
>
>
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