[Moon-net] New photos of 2m-8877

[LANCE COLLISTER]

Edward Cole wrote:
> Just posted some new photos of the 8877 project.
> http://www.kl7uw.com/2m-8877.htm
> 
> How long a time delay needed for 8877 filament inrush current 
> limitation?  I can get maybe ten seconds using a RC time constant 
> timing ckt. controlling relay with 100-ohm resistor to load inrush to 
> filament transformer.  That should lower filament to 3.0 volts at 11 
> amps.  I'll be running 4.9 volts after startup.
> For pretuning the 8877, what resistor value to use across 
> cathode-grid (using MFJ-269).  Can I also pretune output ckts this 
> way and what resistor value for anode-grid?
> 
> *****************************************************
> 73, Ed - KL7UW              BP40iq, 6m - 3cm
> 144-EME: FT-847, mgf-1801, 4x-xp20, 185w
> http://www.kl7uw.com     AK VHF-Up Group
> NA Rep. for DUBUS: dubususa at hotmail.com
> ***************************************************** 
> 
> 
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> 
Hello Ed,

 From what I have read, the most critical time for filament warmup is the first 
few AC CYCLES before the filament has time to warm up at all.  I have used 4 or 5 
seconds delay before going to full filament voltage only because I figured it 
would be better to be safe than sorry.  After 4 or 5 seconds, you can see the 
voltage stabilize at the lower current, meaning the filament has definitely begun 
warming up.  GL and VY 73, Lance

-- 
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: (406) 626-5728   URL: http://www.bigskyspaces.com/w7gj
2m DXCC #11, 6m DXCC #815