Setting Up an "R8 Cushcraft" Vertical Antenna

IV3TMM

Category:

Science & Technology

Tags:

• R8
• Cushcraft
• Vertical
• Antenna
• Hamradio

[iv3tmm]

PY2DS wrote

Hello Francesco. My name is Murilo (py2ds), i bought a Cushcraft R8 in last mounth because i see your vídeo in youtube. Is a very good antenna but my SWR in 20 and especially in 30 meters is high. How i adjust the SWR in this bands?

i wait your help.

Grazie

Murilo

[iv3tmm]

Hi Murilo, first of all i thank you for watching my R8 movie then i can say you to tune your R8 antenna ...

For 20m band there is no easy way to tune antenna because if:

1) your SWR down point is under 14.000 Mhz then it say that antenna is too long !

2) your SWR down point is up 14.350 Mhz then it say that antenna is too short !

so to adjust antenna you have to:

1) cut internal coil trap

2) allonge internal coil trap or allone alluminium tube under 20m coil trap

[iv3tmm]

, but probably this way will change the 17m swr, be careful

In this case you have to open the coil trap, it’ s a bit difficult but not impossible, good luck HI

For 30m is the same way but in this case you can cut or alonge the tube between the two coils trap. In my case i cut 10centimeter the tube between the two coils trap.

I suggest you to check very well the lenght of all alluminium tubes then tune ONLY 20m.

[iv3tmm]

After 20m swr is OK, then check again your swr on 30m and then tune 30m.

Finally check again 40m swr and tune it.

It ‘ s a long way but this is the ONLY RIGHT way to tune R8.

I immagine that 6/10/12/15m swr is OK.

Hope that you will tune your antenna.

73 de Francesco IV3TMM and tomorow on trip to Burundi operating as 9U3TMM for one week, stay tuned.

Ciao.

[QRPPPSK31]

OUTSTANDING! Great R8 antenna job! You and I think alike. Excellent video and the music

couldn't be better. Francesco, I only wish that you lived close to me, and could help me get

my R8 up. Best of DX to you and 73, de Jack K7KGB/QRP.

[iv3tmm]

@QRPPPSK31 Hope that you will set up a good antenna.

Ciao Francesco. Stay tuned ... will be active as 9U3TMM at the end of the year.

[pp5wo]

Muita Parafernalia nesta antena, Meu projeto com todas as Bandas mais 6 metros´bem mais simples ressona com swr de 1:1 com antenaturner é logico. certifique-se no email antenaswaltrick@yahoo.com.br

[QRPPPSK31]

@iv3tmm Tnx fer the info Francesco, I put this R8 up in Dec. of 2006, but took it down

in 2007. It has been in 2 sections, on my back porch for a very long time. See my video

"QRP ANTENNA FARM".Maybe one day I'll have it up once again, rxing and radiating

signals for me. It is a great antenna! 73, de Jack K7KGB/QRP.

[iv3tmm]

@QRPPPSK31 Hi Jack, tnx fer QTC. You welcome.

If you have to setup an R8 remember:

Set up/dwn stub for 6-10-12-15 m (i had to increase with a new stub +20cm the stub for 15m).

Set up/dwn the connection under the 20m trap coil for 17m, not so long but you can move some cm.

20m - you can' t do nothing, only mods lenght of coil trap.

30m - you can cut or change the connection between the two traps (i had to cut 10 cm of alluminium tube for 30m SWR)

40m - tune the last stub on top of R8.

[iv3tmm]

@brubatt Le fascette a croce per gli occhielli dei controventi non sono isolate dai tubi in alluminio della R8 ... non interferiscono. L' importante è che gli occhielli del fili in teflon non tocchino i vari stub altrimenti andrebbero in corto con il tubo principale. Ciao 73 de IV3TMM.