[Yaesu] New cost of Yaesu FT-ONE in the UK

[Rob Atkinson]

On Mon, May 23, 2011 at 4:50 PM, Dr. David Kirkby
<david.kirkby at onetel.net>wrote:


Tubes of course (if you go back 50-60 years), always had a finite life.


A lot of that has to do with how they were treated.   The products made back
then never had proper cooling except maybe for professional equipment.   I
just fixed up a 1952 Admiral 5 tube AM broadcast receiver that originally
had no venting.  The back had no holes in it and the top was solid
bakelite.    The tubes inside cooked.  Ham rigs had more venting but
consumer products like radio receivers and audio amplifiers often had none.
heat kills gear.  But back then, tubes were cheap and in production.
Millions were made, which is a good thing because they are still available
but now, they are not all in production so care for them is a priority.   In
1952 if a tube cooked, no big deal, it cost a dollar and the TV repair shop
down the street had one so replacing them was almost like replacing a light
bulb.   A tube can be made to last longer than us by cooling it with a fan
and secondly, getting the filament supply right which is the other tube
killer.   Now, any ham who knows what he is doing runs his tube gear with
muffin fans and variacs or buck transformers--that way they'll be around for
a long time.   My AA5 Admiral rx works FB on 80 volts : )  The third trick
is to use thermistors on the AC service line into the equipment to limit the
inrush to cold filaments--this trick saves transformers when going to
transmit on AM rigs.   Some of those transformers are now unobtainium.




>
>
>  At one time
>> it was common to find transmitters and receivers for sale that were built
>> for rack mounting, on steel chassis.  Now, everything is lightweight and
>> plastic.
>>
>
> and it looks it!


Yep, but the beautiful aesthetic of black wrinkle, yellow dial lamps and
filaments is still available : )



>
>
>   Even RF power amplifiers are lightweight and cheaply built
>> compared to the 1960s.
>>
>
> I suspect computer modelling of thermal performance has allowed the
> barriers to be pushed more. There is no need to be so conservative.


No, the thing that drove light weight amps was the move to the low SSB duty
cycle.  When it became clear that 95% of buyers were operating 50% d/c or
less, the manufacturers figured out they could use smaller plate supply
transformers etc.  and turned cheapness into a bogus positive:  light weight
easy to move, quiet cooling, compact size.

Rob
K5UJ