Re: [Repeater-Builder] Hamtronics T301 220 exciter Final and microphonics
Bryan Fields wrote: On Monday 19 December 2005 09:55 pm, Kevin Custer wrote: Yes it can... FM that is... Well the distortion I am seeing due to the final looks like AM, but then the vco has FM distortion when you tap the board so it's hard to tell. It's a combo of both. How can the Final in this produce FM of it's own, I would think cuz it's a variable cap on the output it would be AM? That transmitter is extremely microphonic. You are modulating the VCO coil no matter where you are tapping in (on) the exciter/cabinet. YAHOO! GROUPS LINKS Visit your group "Repeater-Builder" on the web. To unsubscribe from this group, send an email to:[EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
Re: [Repeater-Builder] Hamtronics T301 220 exciter Final and microphonics
Kevin Custer wrote: Bryan Fields wrote: On Monday 19 December 2005 09:55 pm, Kevin Custer wrote: Yes it can... FM that is... Well the distortion I am seeing due to the final looks like AM, but then the vco has FM distortion when you tap the board so it's hard to tell. It's a combo of both. How can the Final in this produce FM of it's own, I would think cuz it's a variable cap on the output it would be AM? That transmitter is extremely microphonic. You are modulating the VCO coil no matter where you are tapping in (on) the exciter/cabinet. I bet if you talk loud enough into the side of the board, you can get fairly clean audio! Maybe that 's the answer for those things-mount a good speaker next to the VCO and feed it with rx audio... -- Jim Barbour WD8CHL Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Hamtronics T301 220 exciter Final and microphonics
At 03:55 PM 12/19/2005 -0600, you wrote: It looks like just a bad amp design as the transistor has the collector commen to the case, putting RF on the Heatsink. the heat sink seams to form a capacitor between it and the shield so any movement or heating modulates the signal. ---Modulates it AM wise? Cause there ain't no way it could modulate the signal FM wise.. Ken -- President and CTO - Arcom Communications Makers of state-of-the-art repeater controllers and accessories. http://www.ah6le.net/arcom/index.html We offer complete Kenwood TKR repeater packages! We are now an authorized Telewave Dealer! AH6LE/R - IRLP Node 3000 http://www.irlp.net Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Hamtronics T301 220 exciter Final and microphonics
On Monday 19 December 2005 05:44 pm, Ken Arck wrote: ---Modulates it AM wise? Cause there ain't no way it could modulate the signal FM wise.. Yes AM wise, it varys the output Z which would make a AM signal. We see it on the service monitor when we tap/blow on it. -- Bryan Fields, KB9MCI 18:58:36 up 2 days, 18:05, 2 users, load average: 0.92, 0.91, 0.83 I wonder if I could ever get started in the credit world? Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Hamtronics T301 220 exciter Final and microphonics
Ken Arck wrote: At 03:55 PM 12/19/2005 -0600, you wrote: It looks like just a bad amp design as the transistor has the collector commen to the case, putting RF on the Heatsink. the heat sink seams to form a capacitor between it and the shield so any movement or heating modulates the signal. ---Modulates it AM wise? Cause there ain't no way it could modulate the signal FM wise.. Ken Yes it can... FM that is... Kevin YAHOO! GROUPS LINKS Visit your group "Repeater-Builder" on the web. To unsubscribe from this group, send an email to:[EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
Re: [Repeater-Builder] Hamtronics T301 220 exciter Final and microphonics
I have a similar problem on the Hamtronics REP-200 6m repeater. It is constantly swamping the receiver. I tried a antenna tuner in the transmitter line as well as the antenna line; trying to make the PA Happy. The TX light will go out,. and there will still be power going through the meter, at a higher SWR. It will occaisionally key the 2m repeater which is about a mile away. When the receiver actually is sensitive enough to produce static with the squelch completely open, you can hear it clearing the runway and preparing to take off as the PA decides to sweep the RF spectrum. Some times it just likes to output power after the exciter drops out. Touching the stud nut on the bottom of the chassis while it is transmitting results in RF burn; so it is no wonder it swamps the Receiver; even with a dummy load on the Duplexer at the antenna port. - Original Message - From: Bryan Fields [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Monday, December 19, 2005 4:55 PM Subject: [Repeater-Builder] Hamtronics T301 220 exciter Final and microphonics well I have a T301 on 220 that has some serious power drop off and microphonics issues. I had thought the microphonics were generated in the VCO, and while some of them are, i have traced most down to the final amp. It looks like just a bad amp design as the transistor has the collector commen to the case, putting RF on the Heatsink. the heat sink seams to form a capacitor between it and the shield so any movement or heating modulates the signal. We also have seen the output power go from 4 watts down to 1.2 watts as it heats up. If we put a fan in there the output is stable at about 2 watts, but it modulates the signal with a hum from the moving air. So I was thinking to replace the output transistor with a MRF237 which has the case tied to ground(emitter) which would seam to be a better idea. For the time being we removed the final and are using a small brick amp that puts out 3 watts stable, with no microphonics. So anyone tried this or have a better fix for the issue? -- Bryan Fields, KB9MCI 15:28:02 up 2 days, 14:35, 2 users, load average: 0.85, 0.61, 0.52 Health is merely the slowest possible rate at which one can die. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Hamtronics T301 220 exciter Final and microphonics
On Monday 19 December 2005 09:55 pm, Kevin Custer wrote: Yes it can... FM that is... Well the distortion I am seeing due to the final looks like AM, but then the vco has FM distortion when you tap the board so it's hard to tell. It's a combo of both. How can the Final in this produce FM of it's own, I would think cuz it's a variable cap on the output it would be AM? But still wondering if anyone has changed the transistor out and seen any better results with it. -- Bryan Fields, KB9MCI 22:17:14 up 2 days, 21:24, 2 users, load average: 1.29, 1.16, 1.27 The steady state of disks is full. -- Ken Thompson Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
