I'm using an attenuator like that in my grid-driven 813 amp. It provides a reasonable
drive level as well as improving the SWR seen by the exciter. It's important to heat-sink
them well because they dissipate a lot of power in a small spot.
On 11/26/2012 4:36 PM, Steve Bookout wrote:
Hello all,
Want to re-do the input matching of an old HB 8877 amp. What should I use for
the cathode impedance when calculating my pi network? I recall it was
something like 50-60 ohms.
Also, thinking attenuating the drive power AFTER the T/R relay and before the
matching network. Right now it only takes 22 watts for 1500 out at 4 KV. A
bit touchy to tune (only been like that for 27 yrs.) Would be nicer to tune at
60, or so, watts out. I saw where Henry radio has some attenuators on Ebay
that might fit the bill.
http://www.ebay.com/itm/New-250-Watt-4-dB-50-ohm-Hybrid-Attenuator-up-2-GHz-/390408415503?pt=LH_DefaultDomain_0&hash=item5ae627a90f
Comments?
73 de Steve, NR4M
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Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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