I don't think you need anywhere near as much delay either for the filament or
the plate of
3-500Z's.
All you need to do for the filament is limit the inrush current while it's
cold. A
half-second should be more than enough for this.
It might be possible to increase tube life by gently ramping up the filament
voltage over
a period of several seconds -- I recall manually turning up a filament rheostat
on a 1935
WE BC transmitter many years ago! -- but a simple soft-start doesn't do this.
And the HV delay is needed only to protect the rectifiers while the capacitors
charge. A
few cycles of AC is enough.
I've used 10 or 20 ohms series resistance in soft-start circuits for 3-500Z
amplifiers
(common to plate and filament supplies). If the delay is short, a lower wattage
resistor
(25 watts) can be used. This is fine unless the relay fails to close!
On 1/20/2011 11:57 PM, BEHIELS JEAN-PIERRE wrote:
>
> Hi;
>
> Best wishes for you all for 2011.
>
> I am quit making my own start delay into a old (1988)TL922 amp.
> I made two primary transformer start up delays for : A for filament supply.
> B for HV sequencial
> start-up supply.
>
> A little explanation about my substantial modifications concerning the
> TL922 power supplys.
> By powering-on I switch all ready a resistance of 10 ohm/50W into the
> primary of the filament transformer circuit.
> After about 3 minutes I switch on the HV tension with in series a resistance
> of 47ohm/50W by means of timer T1
> I mean time I also swich-out the 10 ohm/50 W of the primary of the filament
> transformer by means of that same timer T1'
> After 5 minutes I switch-out the 47 ohm/50W resistor of the primary of the
> HV-supply transformer by means of timer T2.
>
> This principle works quit very well and it is very safely for the start-up
> life time of the 3-500Z tubes ?
> But I was a little bit scary about the cuurent (1A over 47 ohms is 47W
> !!!)witch flows of the HV-supply
> without charge during the 47 ohm/50W resistance was in circuit..
> Just some bleeders resistances over the HV-supply C's and over the whole
> supply as stabilisation of the power HV-supply output.
> I could not believe it was about 1A ???
> That was quit a good reason to ask some question around ?
> Today I leave the whole AMP under supply for a whole day nothing happens
> around.
> May I conclude everything is normal behind my old Tl922 ?
>
> So a big story but I like to now some others guys opinion and experiences
> around this remarquable
> consumption of the HV-supply and measurement I made around a TL 922.
>
> 73's Jean ON4AEF.
>
>
>
>
>
>> ----- Original Message -----
> From: "Jim W7RY"<w7ry@inbox.com>
>> To: "BEHIELS JEAN-PIERRE"<ON4AEF@base.be>;<amps@contesting.com>
>>> Sent: Wednesday, January 19, 2011 4:20 PM
>>> Subject: Re: [Amps] Fireing up a old Tl922 amplifier.
>>>
>>>
>>>> How long is your delay? Should be no more than .5 second to 1 second.
>>>>
>>>> 73
>>>> Jim W7RY
>>>>
>>>>
>>>> --------------------------------------------------
>>>> From: "BEHIELS JEAN-PIERRE"<ON4AEF@base.be>
>>>> Sent: Wednesday, January 19, 2011 12:18 AM
>>>> To:<amps@contesting.com>
>>>> Subject: [Amps] Fireing up a old Tl922 amplifier.
>>>>
>>>>> Hi,
>>>>>
>>>>> I am busy to fireing up a old Kenwood TL922 amplifier(1985).
>>>>> I have already build in a start-up system for both filament and high
>>>>> tension power supplys by means of two homebrew timers,and a series
>>>>> small
>>>>> resistances in
>>>>> de secundairys of both transformers(filament 10 ohm-HV 47 ohm both
>>>>> 50W).
>>>>> Both valves are not mounted(running with no charges no consume).
>>>>> By power-on the unit I saw that the resistance of 47ohm/50W into the HV
>>>>> supply is becoming very hot.
>>>>> I have made some measurements during start up around this resistance
>>>>> and
>>>>> measure 47 V over this resistance.
>>>>> This means that the HV power supply without charge consume 1A idling
>>>>> current !!!
>>>>> Question is this normal ?
>>>>> After the timing sequence the resistance is normally pulling out of the
>>>>> system and the supply runs like it must be I suppose,nothing abnormal
>>>>> happens further !!
>>>>> No overheating behind the amplifier box or whatever,no smoke or burning
>>>>> and heating components.
>>>>> Just the 10W bleeders over the capacitors warm up a little (can easely
>>>>> take my hand on it hi )
>>>>> I was wondering while this is so mutch or not ?
>>>>> Did I leave the amp a lot many hours under supplying condition to the
>>>>> give the HV-capacitors the time to reforme after sutch long time(if
>>>>> this
>>>>> is the reason) ???
>>>>> Could this last also a reason of the fenomene ?
>>>>> Or is 1A just normal standby current value for this amp .....
>>>>>
>>>>> Regards Jean ON4AEF.
>>>>>
>>>>> _______________________________________________
>>>>> Amps mailing list
>>>>> Amps@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>>>
>>>>>
>>>>>
>>>>> -----
>>>>> No virus found in this message.
>>>>> Checked by AVG - www.avg.com
>>>>> Version: 10.0.1191 / Virus Database: 1435/3389 - Release Date: 01/18/11
>>>>>
>>>
>>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
--
Vic
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|