[AMRadio] B&W 850-A vs 852 Pi-Network assembly

Geoff/W5OMR ars.w5omr at gmail.com
Mon May 28 22:00:10 EDT 2007

>> The 850A and 852 have the same voltage rating but the plate impedance for
>> the 850A is 2500 to 5000 ohms, while the 852 is 1500 to 3000 ohms.

> Larry WA9VRH wrote:
>> Hi Scott,
>> I will keep looking for an 850-A as it would be the best way to go. Thanks
>> for the info and I would appreciate a copy of the chart.
>> Address and email is good on QRZ.

While I know that the B&W butterfly cap is worlds different from the 
pi-net tuning unit, it should be noted that the wider the impedance 
rage, the easier it's going to be to match it with a 'normal' sized 
capacitor.  The capacitance on the tuning cap in my push-pull, link 
coupled final isn't -quite- enough for 75m.  A split-stator capacitor 
was added in parallel to allow the tank circuit to resonate on 75m.

I understand if you think the 850-A is what you've designed the rig 
around, but from what I see about the 852, it's range is more dynamic.

Something to think about.

73 = Best Regards,

More information about the AMRadio mailing list

This page last updated 25 Feb 2018.