[TowerTalk] Using Stubs to Reject Harmonics

[Jim Hargrave]

Dentron Clipperton-L is pi-network on all bands.
 
   * 73's Jim W5IFP *
     w5ifp at gvtc.com


   >-----Original Message-----
   >From: towertalk-bounces at contesting.com
   >[mailto:towertalk-bounces at contesting.com]On Behalf Of Joe Subich, W4TV
   >Sent: Thursday, February 04, 2010 01:44
   >To: 'Tower and HF antenna construction topics.'
   >Subject: Re: [TowerTalk] Using Stubs to Reject Harmonics
   >
   >
   >
   >
   >Heath SB-1000 and Ameritron AL-80 are pi-L on 160 & 80, pi above 
   >that.  SB-200/SB201/SB-220/SB-221, Drake L4 and L7 are pi-network. 
   >
   >Ameritron ALS-600 is a solid state amp with lowpass filter 
   >outputs (half-wave - "double pi").  
   >
   >73, 
   >
   >   ... Joe, W4TV 
   > 
   >
   >
   >
   >
   >> -----Original Message-----
   >> From: towertalk-bounces at contesting.com 
   >> [mailto:towertalk-bounces at contesting.com] On Behalf Of Jim Brown
   >> Sent: Wednesday, February 03, 2010 4:04 PM
   >> To: Tower and HF antenna construction topics.
   >> Subject: Re: [TowerTalk] Using Stubs to Reject Harmonics
   >> 
   >> 
   >> On Tue, 2 Feb 2010 13:49:36 -0600, Tim Duffy K3LR wrote:
   >> 
   >> >Hi Jim:
   >> 
   >> >I always wanted to test the 1/4 wave "insertion" theory, but 
   >> never got 
   >> >around to it. I would love to hear what the difference is - 
   >> if you can 
   >> >experiment.
   >> 
   >> Tim,
   >> 
   >> I haven't done any measurements, but I did do a literature 
   >> search of QST 
   >> product reviews to learn what output circuitry is used by 
   >> power amps that 
   >> you and I are likely to be using. What I learned is that 
   >> MOST, but not 
   >> all, use the pi-L output configuration -- starting from the 
   >> tube, shunt C, 
   >> series L, shunt C, series L. This configuration allows stubs 
   >> to be placed 
   >> at the output of the power amp. Amps that use this 
   >> configuration include 
   >> the original Ten Tec Titan 425, Alpha 374, 76, 77, 87, 91B, 
   >> ACOM 1000 & 
   >> 1010, Ameritron AL-800H, and QRO-2500DX. The AL-82 and 
   >> AL-1200 use a pi-L 
   >> on 160 and 80, but pi network on the other bands. 
   >> 
   >> I can't find reference to the output network of the current 
   >> model Ten Tec 
   >> Titan III, the Alpha 86 or 89, the ACOM 2000, Heath SB-1000 
   >> or SB-220, 
   >> Ameritron ALS-600, or Tokyo High Power products. If I were 
   >> guessing, it 
   >> would be that they follow suit of other products in their 
   >> heritage. The 
   >> Commander HF-1250 and HF-2500 have a pi-network to match the 
   >> tube to 200 
   >> ohms, then a 4:1 toroidal xmfr. From a network point of view 
   >> (that is, 
   >> interaction with stubs), I'd call it a pi. 
   >> 
   >> The Ten Tec Herc II and Centurion, the Kenwood TL-922A all use pi 
   >> networks. 
   >> 
   >> 73,
   >> 
   >> Jim K9YC  
   >> 
   >> 
   >> _______________________________________________
   >> 
   >> 
   >> 
   >> _______________________________________________
   >> TowerTalk mailing list
   >> TowerTalk at contesting.com 
   >> http://lists.contesting.com/mailman/listinfo/towertalk
   >
   >_______________________________________________
   >
   >
   >
   >_______________________________________________
   >TowerTalk mailing list
   >TowerTalk at contesting.com
   >http://lists.contesting.com/mailman/listinfo/towertalk