Peter,
Yes the Decca's are great transmitters with a bullet-proof
design. I have run mine key down continuously at 1.4kW dc input for
2.5 hours for ERP measurements with no ill effects. I bought spare
MOSFETs from Ebay but thankfully haven't needed them.
My Decca did have an open diode in the guard circuit when I got it,
most likely the result of a lightning strike, but other than that no
worries.
--
73 Warren K2ORS
WD2XGJ
WD2XSH/23
WE2XEB/2
WE2XGR/1
On Thu, May 7, 2009 at 7:26 AM, Peter Dodd <[email protected]> wrote:
> Hi Warren
> I fully agree with you. The Decca 5501's were used in unattended stations
> and transmitting 24/7 under a very heavy duty cycle. There were several
> transmitters all in the same rack transmitting at the same time on different
> frequencies feeding into the same antenna through an ingenious automatic
> multi-tuning system - a remarkable bit of radio engineering.
> I blew the FETs in one of the amplifier units because my 5501 had been
> modified to be dual band 73 and 136kHz and one day when I QSYed I forgot to
> change all the necessary coil taps.
> Check out G4FTCs web site for some interesting pictures of the Decca
> stations.
>
> Regards
>
> Peter, G3LDO
>
>> Mal,
>>
>> You couldn't be more wrong!!!
>> I have been running a Decca in QRSS 60 for several years now at full
>> power + often overnight and occasionally for days at time with ZERO
>> transmitter failures. The Decca runs cool at 1.4 - 1.5 kW DC input.
>> Perhaps you are not allowing for sufficient air circulation through
>> the heat sinks. My Decca is in a rack with plenty of clearance above
>> and below for the air to circulate. I don't think that it's a good
>> idea to run the Decca sitting on a table as I've seen done in some
>> shack pictures.
>>
>>
>
>
>
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