Re: [Repeater-Builder] Hamtronics exciter
Sounds interesting! Maybe I can experiment with this too... 73, Steve - Original Message - From: Kevin Custer To: Repeater-Builder@yahoogroups.com Sent: Wednesday, April 14, 2004 3:42 PM Subject: Re: [Repeater-Builder] Hamtronics exciter Hi Steve,I have had good results FM'ing the TA-51 and TA-451. See here:http://www.repeater-builder.com/rbtip/ta-51pl_mod.htmlWhile this mod was only intended for FM'ing the crystal to get adequate PL deviation with low distortion, I have recently redone my remote receiver projects for one of my 2 meter machines (4 sites). I used the modification as above for voice frequencies as well as PL, the difference from the stock modulator was amazing. While the linearity of the modulator 'as designed' is of no concern when only one frequency is applied (like a PL tone) I was surprised to measure quite acceptable response across the entire range from about 10 cycles to about 5500 cycles. Even though the PM modulator in the UHF exciter shows better response because it's multiplied several more times then on low-band or high-band, FM'ing it made it sound so much better. Obviously, a clipper and low pass filter should be implemented when using any modulator capable of deviating beyond the acceptable bandwidth of the particular service/frequency spectrum.Kevin CusterSteve Grantham wrote: Well... Does anyone think it would be feasible or practical to modify the TA-51 to implement an LC phase modulator? Just how easy or how difficult might that be? Steve - Original Message - From: Kevin Custer To: Repeater-Builder@yahoogroups.com Sent: Tuesday, April 13, 2004 9:46 PM Subject: Re: [Repeater-Builder] Hamtronics exciter [EMAIL PROTECTED] wrote: Hi Kevin, Virgil mentioned that he had looked at the manual and noted that the TA-51 uses RC phase modulation. A-ha! The light went on. You can only get 90 degrees of phase shift max with an RC circuit. Had they used an LC phase modulator, they would have gotten 180 degrees max. That's why the deviation is low with that unit. They don't have much deviation to start with, and as you say, if it isn't multiplied a lot, it'll be low at the final freq.Tell Virgil thanks for the investigation. Also as a side note from practical experience with this type of exciter, and as you have mentioned before as well, the tuning of the first stages after the oscillator are critical for good modulation, otherwise it will be very distorted.Kevin 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 the Yahoo! Terms of Service.
Re: [Repeater-Builder] Hamtronics exciter
Thanks Bob & Greg! As one might imagine,
I really need one more project to do around here ;)
I had looked at the mod Kevin posted, and even
looked for the parts, but none were readily available.
After that, I started giving serious thought to a
wholesale change out to MASTR II radio gear...
I am getting my M2 stuff together, but I'll still
be left with the Hamtronics stuff with the crystals.
Thanks for the tips!
73,
Steve
- Original Message -
From:
Gregg
Lengling
To: Repeater-Builder@yahoogroups.com
Sent: Wednesday, April 14, 2004 2:30
PM
Subject: RE: [Repeater-Builder]
Hamtronics exciter
I've done the
FM
PL mods to this type of
transmitter to get direct FM for CTCSS injection. The modulator on that
exciter will not handle CTCSS so the mod is required for a nice clean PL.
It's a rather simple mod with only a few parts and is documented on the
RepeaterBuilder website.
Gregg R. Lengling, W9DHI,
RetiredAdministrator http://www.milwaukeehdtv.orgK2/100
S#3075 KX1 S# 57Politics is the art of appearing candid and completely
open, while concealing as much as possible. -States: The Bene
Gesserit View
-Original
Message-From:
[EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Wednesday, April 14, 2004 2:05
PMTo:
Repeater-Builder@yahoogroups.comSubject: Re: [Repeater-Builder]
Hamtronics exciter
Hi Steve,
Does anyone think it would be
feasible or practical to modify the TA-51 to implement an LC phase
modulator? Just how easy or how difficult might that
be?
You could use a varicap, a
tunable inductor, and a capacitor to build a circuit that's resonant
at the crystal frequency, and that's fairly easy. But such a circuit also
generates an AM component that must be removed, so another transistor stage
is needed for isolation. That probably means you're up to a little
perf-board ('blob') addition to the exciter.
BTW, we think that the GE PM
exciter suffers from a little of the same insufficient isolation problem,
but that's another rainy-day investigation.
Incidentally, the
RC version of a phase modulator is sometimes
called a reactance modulator, and the LC version is called
a tuned circuit modulator.
73,
Bob,
WA9FBO
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 the Yahoo! Terms of Service.
Re: [Repeater-Builder] Hamtronics exciter
Hi Steve, I have had good results FM'ing the TA-51 and TA-451. See here: http://www.repeater-builder.com/rbtip/ta-51pl_mod.html While this mod was only intended for FM'ing the crystal to get adequate PL deviation with low distortion, I have recently redone my remote receiver projects for one of my 2 meter machines (4 sites). I used the modification as above for voice frequencies as well as PL, the difference from the stock modulator was amazing. While the linearity of the modulator 'as designed' is of no concern when only one frequency is applied (like a PL tone) I was surprised to measure quite acceptable response across the entire range from about 10 cycles to about 5500 cycles. Even though the PM modulator in the UHF exciter shows better response because it's multiplied several more times then on low-band or high-band, FM'ing it made it sound so much better. Obviously, a clipper and low pass filter should be implemented when using any modulator capable of deviating beyond the acceptable bandwidth of the particular service/frequency spectrum. Kevin Custer Steve Grantham wrote: Well... Does anyone think it would be feasible or practical to modify the TA-51 to implement an LC phase modulator? Just how easy or how difficult might that be? Steve - Original Message - From: Kevin Custer To: Repeater-Builder@yahoogroups.com Sent: Tuesday, April 13, 2004 9:46 PM Subject: Re: [Repeater-Builder] Hamtronics exciter [EMAIL PROTECTED] wrote: Hi Kevin, Virgil mentioned that he had looked at the manual and noted that the TA-51 uses RC phase modulation. A-ha! The light went on. You can only get 90 degrees of phase shift max with an RC circuit. Had they used an LC phase modulator, they would have gotten 180 degrees max. That's why the deviation is low with that unit. They don't have much deviation to start with, and as you say, if it isn't multiplied a lot, it'll be low at the final freq. Tell Virgil thanks for the investigation. Also as a side note from practical experience with this type of exciter, and as you have mentioned before as well, the tuning of the first stages after the oscillator are critical for good modulation, otherwise it will be very distorted. Kevin 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 the Yahoo! Terms of Service.
RE: [Repeater-Builder] Hamtronics exciter
I've done the FM PL mods to this type of
transmitter to get direct FM for CTCSS injection. The modulator on that
exciter will not handle CTCSS so the mod is required for a nice clean PL. It's
a rather simple mod with only a few parts and is documented on the RepeaterBuilder
website.
Gregg R. Lengling, W9DHI, Retired
Administrator http://www.milwaukeehdtv.org
K2/100 S#3075 KX1 S# 57
Politics is the art of appearing candid and completely open, while concealing
as much as possible. -States: The Bene Gesserit View
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
Sent: Wednesday, April 14, 2004
2:05 PM
To:
Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder]
Hamtronics exciter
Hi Steve,
Does anyone think it would be
feasible or practical to modify the TA-51 to implement an LC phase
modulator? Just how easy or how difficult might that be?
You could use a varicap, a
tunable inductor, and a capacitor to build a circuit that's resonant
at the crystal frequency, and that's fairly easy. But such a circuit also
generates an AM component that must be removed, so another transistor stage
is needed for isolation. That probably means you're up to a little
perf-board ('blob') addition to the exciter.
BTW, we think that the GE PM exciter
suffers from a little of the same insufficient isolation problem, but
that's another rainy-day investigation.
Incidentally, the
RC version of a phase modulator is sometimes
called a reactance modulator, and the LC version is called
a tuned circuit modulator.
73,
Bob, WA9FBO
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 the Yahoo! Terms of Service.
Re: [Repeater-Builder] Hamtronics exciter
Hi Steve,
Does anyone think it would be feasible or practical to modify the TA-51 to implement an LC phase modulator? Just how easy or how difficult might that be?
You could use a varicap, a tunable inductor, and a capacitor to build a circuit that's resonant at the crystal frequency, and that's fairly easy. But such a circuit also generates an AM component that must be removed, so another transistor stage is needed for isolation. That probably means you're up to a little perf-board ('blob') addition to the exciter.
BTW, we think that the GE PM exciter suffers from a little of the same insufficient isolation problem, but that's another rainy-day investigation.
Incidentally, the RC version of a phase modulator is sometimes called a reactance modulator, and the LC version is called a tuned circuit modulator.
73,
Bob, WA9FBO
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 the Yahoo! Terms of Service.
Re: [Repeater-Builder] Hamtronics exciter
Well... Does anyone think it would be feasible or practical to modify the TA-51 to implement an LC phase modulator? Just how easy or how difficult might that be? Steve - Original Message - From: Kevin Custer To: Repeater-Builder@yahoogroups.com Sent: Tuesday, April 13, 2004 9:46 PM Subject: Re: [Repeater-Builder] Hamtronics exciter [EMAIL PROTECTED] wrote: Hi Kevin, Virgil mentioned that he had looked at the manual and noted that the TA-51 uses RC phase modulation. A-ha! The light went on. You can only get 90 degrees of phase shift max with an RC circuit. Had they used an LC phase modulator, they would have gotten 180 degrees max. That's why the deviation is low with that unit. They don't have much deviation to start with, and as you say, if it isn't multiplied a lot, it'll be low at the final freq.Tell Virgil thanks for the investigation. Also as a side note from practical experience with this type of exciter, and as you have mentioned before as well, the tuning of the first stages after the oscillator are critical for good modulation, otherwise it will be very distorted.Kevin 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 the Yahoo! Terms of Service.
Re: [Repeater-Builder] Hamtronics exciter
[EMAIL PROTECTED] wrote: Hi Kevin, Virgil mentioned that he had looked at the manual and noted that the TA-51 uses RC phase modulation. A-ha! The light went on. You can only get 90 degrees of phase shift max with an RC circuit. Had they used an LC phase modulator, they would have gotten 180 degrees max. That's why the deviation is low with that unit. They don't have much deviation to start with, and as you say, if it isn't multiplied a lot, it'll be low at the final freq. Tell Virgil thanks for the investigation. Also as a side note from practical experience with this type of exciter, and as you have mentioned before as well, the tuning of the first stages after the oscillator are critical for good modulation, otherwise it will be very distorted. Kevin 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 the Yahoo! Terms of Service.
[Repeater-Builder] Hamtronics exciter
Hi Kevin, Wanted to get back to you about a discontinued thread. You wrote: Hamtronics mentions in their manual for the TA-51 (a little PM exciter they have built and sold for years) that a full 5 kc of deviation *may not* be possible without distortion because the multiplication factor is only 4 times with their 6 meter exciter. (Read page 7 of the following manual):http://www.hamtronics.com/pdf/inst%20manuals/TA51.pdf Virgil mentioned that he had looked at the manual and noted that the TA-51 uses RC phase modulation. A-ha! The light went on. You can only get 90 degrees of phase shift max with an RC circuit. Had they used an LC phase modulator, they would have gotten 180 degrees max. That's why the deviation is low with that unit. They don't have much deviation to start with, and as you say, if it isn't multiplied a lot, it'll be low at the final freq. 73, Bob 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 the Yahoo! Terms of Service.
