Re: Topband: Battle Creek Special - 160 Resonance
Hi I have note from George and its on our webpage https://www.pi4cc.nl/link/extra.php Peter PC2A Dear OM Peter: Something you need to know about your website: The Battle Creek Special is designed for use from 7.0 to 7.3 MHz and the trap should be resonated close to 7.0, not 7.1 MHz. On 80 meters the design frequency is 3525 KHz, and the bandwidth is 3500 to 3570 KHz. The trap needs to resonate at or below 3525. The trap data you give will resonate at 3750 KHZ which will reduce the performance on 80 CW and may give other problems. The capacitance to resonante 9 uHy at 3.5 MHz is about 225 pfd. The Battle Creek Special uses two pieces of RG-213 about 4 feet long, in parallel, to get this capacity and they hang below the trap inside the top section. Please correct your diagrams to reflect this. Also do not forget the 2:1 UnUn (9:4 UnUn also works) to bring the impedance on 160 up to about 50 ohms. With L=9 uHy, C is best at 229 or 230 pfd for resonance nearest 3500 KHz With C = 200 pfd, L is best at 10.33 uHy for resonance at 3500 KHz 73 George K8GG Battle Creek, Michigan Op 30-10-2016 om 0:16 schreef thoyer: I built this antenna several years ago. I never really had a good resonance on 160 though. Best I could do was 3.5:1 or so. I used the xcvr ant tuner to match it without issue. Since it had been up for many years I brought it down a couple weeks back for maintenance. I reworked the traps and adjusted the length of the first section to give me a better match in the CW portion of 40m. The reworked traps dip at approx 7.12mhz for the 40m trap and 3.5mhz for the 80m trap. Put the antenna back up today and have a nice match in the CW portion of 40, but the 80m resonance has shifted down to around 3.3mhz and I see no resonance on 160m. Some numbers from the MFJ analyzer: 40m 7.05mhz 44, 10 and 1.2 VSWR 80m 3.51mhz 91, 136 and 5.8 VSWR 160m 1.81mhz 18, 37 and 4.1 VSWR I have about 40 radials varying in length from 50 to 60 feet depending on the yard. The 80m loading wire is approx 15' long The 160m "L" is approx 72 feet long The overall height of the antenna is 50ft. Any suggestions for how to obtain a better resonance on 160? Tom W3TA _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Fw: Battle Creek Special - 160 Resonance
- Forwarded Message - From: HAROLD SMITH JRTo: "thoy...@verizon.net" To: topband@contesting.com Sent: Saturday, October 29, 2016 5:16 PM Subject: Topband: Battle Creek Special - 160 Resonance I built this antenna several years ago. I never really had a good resonance on 160 though. Best I could do was 3.5:1 or so. I used the xcvr ant tuner to match it without issue. Since it had been up for many years I brought it down a couple weeks back for maintenance. I reworked the traps and adjusted the length of the first section to give me a better match in the CW portion of 40m. The reworked traps dip at approx 7.12mhz for the 40m trap and 3.5mhz for the 80m trap. Put the antenna back up today and have a nice match in the CW portion of 40, but the 80m resonance has shifted down to around 3.3mhz and I see no resonance on 160m. Some numbers from the MFJ analyzer: 40m 7.05mhz 44, 10 and 1.2 VSWR 80m 3.51mhz 91, 136 and 5.8 VSWR 160m 1.81mhz 18, 37 and 4.1 VSWR I have about 40 radials varying in length from 50 to 60 feet depending on the yard. The 80m loading wire is approx 15' long The 160m "L" is approx 72 feet long The overall height of the antenna is 50ft. Any suggestions for how to obtain a better resonance on 160? Tom W3TA _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Battle Creek Special - 160 Resonance
I built this antenna several years ago. I never really had a good resonance on 160 though. Best I could do was 3.5:1 or so. I used the xcvr ant tuner to match it without issue. Since it had been up for many years I brought it down a couple weeks back for maintenance. I reworked the traps and adjusted the length of the first section to give me a better match in the CW portion of 40m. The reworked traps dip at approx 7.12mhz for the 40m trap and 3.5mhz for the 80m trap. Put the antenna back up today and have a nice match in the CW portion of 40, but the 80m resonance has shifted down to around 3.3mhz and I see no resonance on 160m. Some numbers from the MFJ analyzer: 40m 7.05mhz 44, 10 and 1.2 VSWR 80m 3.51mhz 91, 136 and 5.8 VSWR 160m 1.81mhz 18, 37 and 4.1 VSWR I have about 40 radials varying in length from 50 to 60 feet depending on the yard. The 80m loading wire is approx 15' long The 160m "L" is approx 72 feet long The overall height of the antenna is 50ft. Any suggestions for how to obtain a better resonance on 160? Tom W3TA _ Topband Reflector Archives - http://www.contesting.com/_topband