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Amp Design Concept -- Preliminary
Enough of that cheap one-board crap..... this amp is MODULAR! Modular design allows easy repair and modification, as well as ease of construction and interchangeability between different amps. It also allows seperation of functions both electronically and physically. The modules include: * Input module. Includes variable attenuator and dummy load which provides adjustment of input power without 'tweaking' anything inside the radio. * Control module. Board that controls keying, bias & cooling fan. * Sensor module. Board with circuits that take measurements from various locations throughout the amp and sends them to a meter. Meter function selection can be by rotory switch or by LCD display simply by swapping the board (module). Meter functions may include: - RF input power, Fwd - RF input power, Ref (for matching amp input to radio output) - Base current - Emitter voltage, (RMS) - Emitter voltage, (peak) - Emitter current - RF output power, Fwd (RMS) - RF output power, Fwd (Peak) - RF output power, Fwd (Peak & hold) - RF output power, Ref - AF input (Ext. mod. function, AM only, see below) - DC supply voltage, amp - DC supply voltage, radio - DC supply current, amp - DC supply current, radio * Power Amplifier Module. The module will consist of the amplifier circuit, heat sink and cooling fan, constructed inside an enclosed sub-chassis designed for forced-air cooling. Flying in the face of convention, the power amplifier circuit will -not- be mounted on a PC board. Instead, the components will be chassis-wired with heavy-guage copper, except for the transistors which will be wired with strips of copper sheet having rounded edges and corners. This allows easy repair and modification, as well as more secure and robust connections. Circuit will be an ultra-linear, broadband, AB push-pull design (details at a later date). * Output module. Includes matching network and output connector, the type of which depends on the desired output method: balanced or unbalanced. The reason is that an unbalanced output is fine for mobile amps where the amp is mounted to an adequate RF ground, but that is rarely the case with base amps. So an option is provided for balanced output; the line can then be run to a point where a good RF ground can be found (e.g, a ground rod right outside the window) where it is coupled to a coax with a balun, or simply run balanced right to the antenna. The user now has these choices and they are built right into the amp! * Power supply module (optional). Power transistors that are designed for higher voltage are more linear and -much- more reliable than those designed to operate on 12-14 volts. This switching power supply bumps up the voltage to 28 or 50 VDC and allows the use of such transistors. Additional features: * An external modulation function can be included, allowing the amp to function as a Class C modulator. Audio input is via a terminal strip on the back and fed from a common 8-ohm audio amplifier. The base bias is then adjusted (with a screwdriver through a hole in front panel) to Class C operation for higher efficiency. This works only in AM mode. There is no provision for audio filtering, so hi-fi (wideband) AM is possible if desired. * Connections for remote operation: - Key ground - Key on ground - Key on high (=+5VDC) - Key function select 1 (amp in/out) - Key function select 2 (key auto/manual) - Key function select 3 (AM/SSB) I am open to any comments or suggestions, provided they are limited in scope to the design concept and desired features. |
Amp Design Concept -- Preliminary
"Frank Gilliland" wrote in message ... I am open to any comments or suggestions, provided they are limited in scope to the design concept and desired features. Yes, what are you going on about? Are you talking about an amp that exists, something you would like to see or something you want. You have just quoted a load of nonsense. |
Amp Design Concept -- Preliminary
On Tue, 19 Sep 2006 22:51:37 +0100, "malc" wrote in
: "Frank Gilliland" wrote in message .. . I am open to any comments or suggestions, provided they are limited in scope to the design concept and desired features. Yes, what are you going on about? Are you talking about an amp that exists, something you would like to see or something you want. You have just quoted a load of nonsense. This is a project to design and build an amp. Once the preliminary design is complete it will be built, tested and refined. All final design parameters will be released for public use. Feel free to contribute. |
Amp Design Concept -- Preliminary
Modular design has its benefits but it also has at least two
disadvantages. 1. Initial cost 2. Problematic connections/connectors between high current modules. |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
Flying in the face of convention, the power amplifier circuit will -not- be mounted on a PC board. Instead, the components will be chassis-wired with heavy-guage copper, except for the transistors which will be wired with strips of copper sheet having rounded edges and corners. No PCB!... transistors wired with strips of copper... sounds like a Davemade... better known as a "prototype"... LOL www.telstar-electronics.com |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
Enough of that cheap one-board crap..... this amp is MODULAR! Cool. How about a high drive portable to go behind an HF rig? Variable input 25/100w. |
Amp Design Concept -- Preliminary
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Amp Design Concept -- Preliminary
On 19 Sep 2006 16:54:16 -0700, "Telstar Electronics"
wrote in om: Frank Gilliland wrote: Flying in the face of convention, the power amplifier circuit will -not- be mounted on a PC board. Instead, the components will be chassis-wired with heavy-guage copper, except for the transistors which will be wired with strips of copper sheet having rounded edges and corners. No PCB!... transistors wired with strips of copper... sounds like a Davemade... better known as a "prototype"... LOL No PCB = no cracked traces, copper seperation, no burnt boards, better heat dissipation, more efficient conductors, etc, etc. Let's face it: replace the power transistors more than twice on a PCB and your board (and therfore your amp) is garbage. Not only that, but it also allows the flexibility to use transistors of different physical sizes and styles; i.e, the amp can be upgraded or retrofit as desired. |
Amp Design Concept -- Preliminary
On 20 Sep 2006 00:26:10 GMT, Steveo wrote in
: Frank Gilliland wrote: Enough of that cheap one-board crap..... this amp is MODULAR! Cool. How about a high drive portable to go behind an HF rig? Variable input 25/100w. The intent is to drive this from a stock CB, but if you want scale it up then it's an easy design modification to the input module. I can include that as an option in the design. However, know that if FET's are used for power transistors then most of your 25/100 watt drive would be wasted. |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
On 20 Sep 2006 00:26:10 GMT, Steveo wrote in : Frank Gilliland wrote: Enough of that cheap one-board crap..... this amp is MODULAR! Cool. How about a high drive portable to go behind an HF rig? Variable input 25/100w. The intent is to drive this from a stock CB, but if you want scale it up then it's an easy design modification to the input module. I can include that as an option in the design. However, know that if FET's are used for power transistors then most of your 25/100 watt drive would be wasted. Are FET's the most economical transistors, or are are there other choices for a 10 meter portable amp? The high drive would make it a bit more legal too, wouldn't it? (dunno, just curious) |
Amp Design Concept -- Preliminary
On Tue, 19 Sep 2006 18:09:10 -0700, Frank Gilliland
wrote in : However, know that if FET's are used for power transistors then most of your 25/100 watt drive would be wasted. Come to think of it, that power wouldn't be wasted at all. I just remembered a neat little power splitter circuit I designed a few years ago; using that I can tap off a signal for the amp and the rest can be rectified, filtered, and fed back into the power supply. So nothing is wasted except in conversion. |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
On Tue, 19 Sep 2006 18:09:10 -0700, Frank Gilliland wrote in : However, know that if FET's are used for power transistors then most of your 25/100 watt drive would be wasted. Come to think of it, that power wouldn't be wasted at all. I just remembered a neat little power splitter circuit I designed a few years ago; using that I can tap off a signal for the amp and the rest can be rectified, filtered, and fed back into the power supply. So nothing is wasted except in conversion. Waste not want not. |
Amp Design Concept -- Preliminary
On 20 Sep 2006 01:13:01 GMT, Steveo wrote in
: Frank Gilliland wrote: On 20 Sep 2006 00:26:10 GMT, Steveo wrote in : Frank Gilliland wrote: Enough of that cheap one-board crap..... this amp is MODULAR! Cool. How about a high drive portable to go behind an HF rig? Variable input 25/100w. The intent is to drive this from a stock CB, but if you want scale it up then it's an easy design modification to the input module. I can include that as an option in the design. However, know that if FET's are used for power transistors then most of your 25/100 watt drive would be wasted. Are FET's the most economical transistors, or are are there other choices for a 10 meter portable amp? The high drive would make it a bit more legal too, wouldn't it? (dunno, just curious) Bipolars are better for higher drive, but the more efficient setup would be an FET amp with a low-power exciter. |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
On 20 Sep 2006 01:13:01 GMT, Steveo wrote in : Frank Gilliland wrote: On 20 Sep 2006 00:26:10 GMT, Steveo wrote in : Frank Gilliland wrote: Enough of that cheap one-board crap..... this amp is MODULAR! Cool. How about a high drive portable to go behind an HF rig? Variable input 25/100w. The intent is to drive this from a stock CB, but if you want scale it up then it's an easy design modification to the input module. I can include that as an option in the design. However, know that if FET's are used for power transistors then most of your 25/100 watt drive would be wasted. Are FET's the most economical transistors, or are are there other choices for a 10 meter portable amp? The high drive would make it a bit more legal too, wouldn't it? (dunno, just curious) Bipolars are better for higher drive, but the more efficient setup would be an FET amp with a low-power exciter. Gotcha. What about the legal part of the question? |
Amp Design Concept -- Preliminary
On 20 Sep 2006 01:23:28 GMT, Steveo wrote in
: Frank Gilliland wrote: On 20 Sep 2006 01:13:01 GMT, Steveo wrote in : Frank Gilliland wrote: On 20 Sep 2006 00:26:10 GMT, Steveo wrote in : Frank Gilliland wrote: Enough of that cheap one-board crap..... this amp is MODULAR! Cool. How about a high drive portable to go behind an HF rig? Variable input 25/100w. The intent is to drive this from a stock CB, but if you want scale it up then it's an easy design modification to the input module. I can include that as an option in the design. However, know that if FET's are used for power transistors then most of your 25/100 watt drive would be wasted. Are FET's the most economical transistors, or are are there other choices for a 10 meter portable amp? The high drive would make it a bit more legal too, wouldn't it? (dunno, just curious) Bipolars are better for higher drive, but the more efficient setup would be an FET amp with a low-power exciter. Gotcha. What about the legal part of the question? What about it? |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
On 20 Sep 2006 01:23:28 GMT, Steveo wrote in : Frank Gilliland wrote: On 20 Sep 2006 01:13:01 GMT, Steveo wrote in : Frank Gilliland wrote: On 20 Sep 2006 00:26:10 GMT, Steveo wrote in : Frank Gilliland wrote: Enough of that cheap one-board crap..... this amp is MODULAR! Cool. How about a high drive portable to go behind an HF rig? Variable input 25/100w. The intent is to drive this from a stock CB, but if you want scale it up then it's an easy design modification to the input module. I can include that as an option in the design. However, know that if FET's are used for power transistors then most of your 25/100 watt drive would be wasted. Are FET's the most economical transistors, or are are there other choices for a 10 meter portable amp? The high drive would make it a bit more legal too, wouldn't it? (dunno, just curious) Bipolars are better for higher drive, but the more efficient setup would be an FET amp with a low-power exciter. Gotcha. What about the legal part of the question? What about it? Does the 25 watt -in- requirement make it anymore legal, or no? ( I really don't know) |
Amp Design Concept -- Preliminary
On 20 Sep 2006 01:30:33 GMT, Steveo wrote in
: snip Does the 25 watt -in- requirement make it anymore legal, or no? ( I really don't know) A ham could probably confirm this, but I think the minimum is 50 watts input (with a license, of course..... without one it's no more legal than having 5 watts input). Regarding -compliance- with the law, just follow the leadership example set by our president and Congress. |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
On 20 Sep 2006 01:30:33 GMT, Steveo wrote in : snip Does the 25 watt -in- requirement make it anymore legal, or no? ( I really don't know) A ham could probably confirm this, but I think the minimum is 50 watts input (with a license, of course. Well yeah a guy is supposed to know CW to transmit voice on 10 meters...of course. (I thought it was 25w or maybe they've up'd it since then?) .... without one it's no more legal Right, and a legal one would be a whole lot easier to advertise so the bottom line should be better. (just throwing my two cents in fwiw) than having 5 watts input). Regarding -compliance- with the law, just follow the leadership example set by our president and Congress. Do I have to? That's nasty. |
Amp Design Concept -- Preliminary
On 20 Sep 2006 01:49:32 GMT, Steveo wrote in
: snip than having 5 watts input). Regarding -compliance- with the law, just follow the leadership example set by our president and Congress. Do I have to? That's nasty. LOL!!! |
Amp Design Concept -- Preliminary
Frank Gilliland wrote: No PCB = no cracked traces, copper seperation, no burnt boards, better heat dissipation, more efficient conductors, etc, etc. Let's face it: replace the power transistors more than twice on a PCB and your board (and therfore your amp) is garbage. Not only that, but it also allows the flexibility to use transistors of different physical sizes and styles; i.e, the amp can be upgraded or retrofit as desired. You're losin' it... no PCB at RF frequencies means wires and uncontrolled inductances / resonances all over the place causing instabilities... resulting in oscillations. Why don't you think any commercial amps are built your way. Great idea Frank... LOL... you're truly a great engineer! www.telstar-electronics.com |
Amp Design Concept -- Preliminary
Steveo wrote:
Are FET's the most economical transistors, or are are there other choices for a 10 meter portable amp? The high drive would make it a bit more legal too, wouldn't it? (dunno, just curious) FETs like the MRF173 (or similar) have certain advantages. They also have several disadvantages... one is cost! Franks proposed design already looks to have a hefty price tag as described. www.telstar-electronics.com |
Amp Design Concept -- Preliminary
On 20 Sep 2006 02:53:13 -0700, "Telstar Electronics"
wrote in om: Frank Gilliland wrote: No PCB = no cracked traces, copper seperation, no burnt boards, better heat dissipation, more efficient conductors, etc, etc. Let's face it: replace the power transistors more than twice on a PCB and your board (and therfore your amp) is garbage. Not only that, but it also allows the flexibility to use transistors of different physical sizes and styles; i.e, the amp can be upgraded or retrofit as desired. You're losin' it... no PCB at RF frequencies means wires and uncontrolled inductances / resonances all over the place causing instabilities... resulting in oscillations. Why don't you think any commercial amps are built your way. Great idea Frank... LOL... you're truly a great engineer! How do you think amps and transmitters were built before the PCB was invented? In fact, how do you think most broadcast transmitters (many of which are still in use today) were built? By mounting a 4CX5000 on a PCB? Why do you think the old chassis-wired Heathkits command a much higher price than the later versions with more features but built with PC boards? And did you know that UHF transmitters also existed long before PC boards, were also constructed with point-to-point wiring, and worked without the problems you claim are inevitable.... on HF? I can cite dozens of examples of power equipment, both audio and radio, that have histories of failure due to the use of PC boards instead of hard wiring. I think Peavey is about the worst offender in that department, in my own personal experience. So you can fabricate any unfounded fear-tactic you like, the fact is that PC boards (including the newer epoxy boards) just aren't adequate for any high-power applications, let alone RF power applications. And point-to-point wiring is a time-tested method that only seems to cause problems for those who need a computer to tell them how to route the wiring. |
Amp Design Concept -- Preliminary
On 20 Sep 2006 04:28:52 -0700, "Telstar Electronics"
wrote in .com: Steveo wrote: Are FET's the most economical transistors, or are are there other choices for a 10 meter portable amp? The high drive would make it a bit more legal too, wouldn't it? (dunno, just curious) FETs like the MRF173 (or similar) have certain advantages. They also have several disadvantages... one is cost! Franks proposed design already looks to have a hefty price tag as described. That's because I don't make cheap, disposable crap. Never have, never will. But the use of FET's is at the discretion of the builder. The amp can be built with either FET's or bipolars. No other modifications are necessary, just a variation in the initial alignment. |
Amp Design Concept -- Preliminary
On a sunny day (20 Sep 2006 04:28:52 -0700) it happened "Telstar Electronics"
wrote in .com: Steveo wrote: Are FET's the most economical transistors, or are are there other choices for a 10 meter portable amp? The high drive would make it a bit more legal too, wouldn't it? (dunno, just curious) FETs like the MRF173 (or similar) have certain advantages. They also have several disadvantages... one is cost! Franks proposed design already looks to have a hefty price tag as described. www.telstar-electronics.com http://www.sphere.bc.ca/test/rf-semis.html |
Amp Design Concept -- Preliminary
On a sunny day (20 Sep 2006 02:53:13 -0700) it happened "Telstar Electronics"
wrote in om: Frank Gilliland wrote: No PCB = no cracked traces, copper seperation, no burnt boards, better heat dissipation, more efficient conductors, etc, etc. Let's face it: replace the power transistors more than twice on a PCB and your board (and therfore your amp) is garbage. Not only that, but it also allows the flexibility to use transistors of different physical sizes and styles; i.e, the amp can be upgraded or retrofit as desired. You're losin' it... no PCB at RF frequencies means wires and uncontrolled inductances / resonances all over the place causing instabilities... resulting in oscillations. Why don't you think any commercial amps are built your way. Great idea Frank... LOL... you're truly a great engineer! www.telstar-electronics.com Well, not exactly, I had in the long ago past a nice 40MHz army transceiver, toobes!!! (called '32set' IIRC) 40 MHz FM full of toobes and no PCB anywhere. My own 500W linear PEP with toobe had no PCB either. If you go to a real shortwave station, 10kW and up, they use big plumbing, big toobes sometimes... (these days transistors too in modules OK). PCB (an as already mentioned by somebody): the thickness of PCB traces becomes a BIG issue especially if you run 1kW at 12V, a few milli-ohm will give you big i^2 x R losses. So copper strip is better anyways, lower current, and higher voltages, FETS, means lower losses, you will need the switch-mode to get the higher voltage. Switch-mode design 50V many amps is an art in itself, I have done switchmode design for a company, it will take you study and time, and likely a few transistor failures. Soldering copper strips to these transistors will require you to support these with proper spacers, so as not to mechanically load the transistors too much. Else vibrations will rip the connections right of over time. I like Franks idea, it is a lot like this one: http://www.ibelings.com/n4ip/mrf157.html I looked up the price of those FETS, 475$ each :-) But I also found a pair on offer for less then 60$, was already gone however. http://www.sphere.bc.ca/test/rf-semis.html other interesting stuff there too:-) In my school days I used to sell Motorola parts...... to finance my hobby. So, anyways, long before the kids had PeeSeeBees the big boys were using copper [wiring], and it did not [always] oscillate. And in the old toobe times the voltages were more 'electrifying' too, mine ran on 1kV, some used much higher voltage power supplies, dangerous these big capacitors. So the Telstar amp is just a small toy..... compared to what was done already in and just after WW2. But do not let that put you off, it looks like a nice amp. And Frank will still have to build his ;-) BTW you Americans have 110V, I had some BUZ44A (IIRC) MOSFETS that can do 500V DC, these oscillated (unwanted) around 20MHz, one could just plug it in for a base station.... No voltage converter needed, not even a transformer. Not sure if something like BUZ44A can be used as an amp.... at 27MHz. http://www.datasheetarchive.com/data...rticle=1048164 probably to much input capacitance 1600 pF..... But looking around for a nice FET may be worth it. |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
That's because I don't make cheap, disposable crap. Never have, never will. But the use of FET's is at the discretion of the builder. The amp can be built with either FET's or bipolars. No other modifications are necessary, just a variation in the initial alignment. Let me get this straight...swapping FETs with bi-polars in the design... and no modifications are necessary??? Get real... there are impedance matching issues, possibly B+ sources level differences, as well as well as totally different biasing circuitry. You are going to bias Frank?... right? www.telstar-electronics.com |
Amp Design Concept -- Preliminary
On Tue, 19 Sep 2006 14:31:52 -0700, Frank Gilliland
wrote: +++ +++Enough of that cheap one-board crap..... this amp is MODULAR! +++ +++Modular design allows easy repair and modification, as well as ease of +++construction and interchangeability between different amps. It also +++allows seperation of functions both electronically and physically. The +++modules include: +++ +++* Input module. Includes variable attenuator and dummy load which +++provides adjustment of input power without 'tweaking' anything inside +++the radio. +++ ************* An attenuator on the input is nice. I am not sure a variable one is needed. By variable a multistep attenuator with four to six different values of attenuation would be a sufficient. A capability to switch the input drive to a internal du mmy load would nice luxury item but not necessary. +++* Control module. Board that controls keying, bias & cooling fan. +++ +++* Sensor module. Board with circuits that take measurements from +++various locations throughout the amp and sends them to a meter. Meter +++function selection can be by rotory switch or by LCD display simply by +++swapping the board (module). Meter functions may include: +++ ***************** Man talk about monitoring circuits. Nice thing to have on a high tier amp. In reality most of these are great for development and early testing. Actual production would cause product cost to sky rocket. +++ - RF input power, Fwd +++ - RF input power, Ref (for matching amp input to radio output) ************ Redundant circuitry since most modern tranceivers todday have some form a SWR bridge incorparated into the transmitter. Would be more needed if the run of coax from the transceiver to the amp were rather long. +++ - Base current **************** If you are into monitoring everything, I would add a monitor of base bias voltage also. +++ - Emitter voltage, (RMS) +++ - Emitter voltage, (peak) +++ - Emitter current +++ - RF output power, Fwd (RMS) +++ - RF output power, Fwd (Peak) +++ - RF output power, Fwd (Peak & hold) +++ - RF output power, Ref +++ - AF input (Ext. mod. function, AM only, see below) +++ - DC supply voltage, amp +++ - DC supply voltage, radio +++ - DC supply current, amp +++ - DC supply current, radio +++ +++* Power Amplifier Module. The module will consist of the amplifier +++circuit, heat sink and cooling fan, constructed inside an enclosed +++sub-chassis designed for forced-air cooling. Flying in the face of +++convention, the power amplifier circuit will -not- be mounted on a PC +++board. Instead, the components will be chassis-wired with heavy-guage +++copper, except for the transistors which will be wired with strips of +++copper sheet having rounded edges and corners. This allows easy repair +++and modification, as well as more secure and robust connections. +++Circuit will be an ultra-linear, broadband, AB push-pull design +++(details at a later date). +++ **************** AIr dielectric striplines are nice for the power transistors. They do introduce some memchanical issues. Great if you are in the 2KW or more output range. In the 100 to 250 watt range 2 ounce copper laminate would be quite sufficient. If varying dielectric constants are an issue then a use of teflon laminate would be preferable over that of FR4/FR5 laminates. Even alumina ceramics would offer a more stable dielectrtic for the striplines. Most of the low level, low current components do not require "dead bug" style mounting. Laminates will do nicely. If you really want to go whole hog on the striplines then why not take the copper strips and either silver or gold plate them. Word of caution on gold over copper. Nickel is not a good conductor of RF. Nickel is usually plated onto copper to give gold a hard surface to plate to. Plating gold directly onto copper requires a much thicker plating so that the copper will not leach through the gold. +++* Output module. Includes matching network and output connector, the +++type of which depends on the desired output method: balanced or +++unbalanced. The reason is that an unbalanced output is fine for mobile +++amps where the amp is mounted to an adequate RF ground, but that is +++rarely the case with base amps. So an option is provided for balanced +++output; the line can then be run to a point where a good RF ground can +++be found (e.g, a ground rod right outside the window) where it is +++coupled to a coax with a balun, or simply run balanced right to the +++antenna. The user now has these choices and they are built right into +++the amp! +++ +++* Power supply module (optional). Power transistors that are designed +++for higher voltage are more linear and -much- more reliable than those +++designed to operate on 12-14 volts. This switching power supply bumps +++up the voltage to 28 or 50 VDC and allows the use of such transistors. +++ +++ +++Additional features: +++ +++* An external modulation function can be included, allowing the amp to +++function as a Class C modulator. Audio input is via a terminal strip +++on the back and fed from a common 8-ohm audio amplifier. The base bias +++is then adjusted (with a screwdriver through a hole in front panel) to +++Class C operation for higher efficiency. This works only in AM mode. +++There is no provision for audio filtering, so hi-fi (wideband) AM is +++possible if desired. +++ ********************* Man after designing such a high tier amp, you adjust the bias through a panel hole with a screwdriver? Will you supply the gold plated screwdriver? I can understand why no band limiting filter designed in since most CBers would bypass that anyway. Th en again, ,a hightier amp as this would be nice to include it to show CBers what a nice thing to hear band limited audio on the desired channel and not 20 channels away. +++* Connections for remote operation: +++ - Key ground +++ - Key on ground +++ - Key on high (=+5VDC) +++ - Key function select 1 (amp in/out) +++ - Key function select 2 (key auto/manual) +++ - Key function select 3 (AM/SSB) +++ +++ +++I am open to any comments or suggestions, provided they are limited in +++scope to the design concept and desired features. +++ +++ +++ *********** Oh well what the heck :) james |
Amp Design Concept -- Preliminary
On 20 Sep 2006 02:53:13 -0700, "Telstar Electronics"
wrote: +++ +++Frank Gilliland wrote: +++ No PCB = no cracked traces, copper seperation, no burnt boards, better +++ heat dissipation, more efficient conductors, etc, etc. Let's face it: +++ replace the power transistors more than twice on a PCB and your board +++ (and therfore your amp) is garbage. Not only that, but it also allows +++ the flexibility to use transistors of different physical sizes and +++ styles; i.e, the amp can be upgraded or retrofit as desired. +++ +++You're losin' it... no PCB at RF frequencies means wires and +++uncontrolled inductances / resonances all over the place causing +++instabilities... resulting in oscillations. Why don't you think any +++commercial amps are built your way. +++Great idea Frank... LOL... you're truly a great engineer! +++ +++www.telstar-electronics.com *************** Below about 1 KW, PCBs are adequate. In the 10 to 20KW range forget laminates. You would have to plate at least 3 ounce if not 4 ounce copper. Beisdes most laminates will have tremendous problems with RF currents at these power levels. AIr dielectric or even ceramics provide a better solution. Also I believe Frank never mentioned the actual power out of his design. james |
Amp Design Concept -- Preliminary
On Tue, 19 Sep 2006 18:41:35 -0700, Frank Gilliland
wrote: +++On 20 Sep 2006 01:30:33 GMT, Steveo wrote in : +++ +++snip +++Does the 25 watt -in- requirement make it anymore legal, or no? ( I really +++don't know) +++ +++ +++A ham could probably confirm this, but I think the minimum is 50 watts +++input (with a license, of course..... without one it's no more legal +++than having 5 watts input). Regarding -compliance- with the law, just +++follow the leadership example set by our president and Congress. +++ +++ ********** The FCC does not actually place a power limitation on the drive. Instead the specifiy the maximum gain of the amp at 15dB. So with 2KW output that would correspond to about 60 watt drive. james |
Amp Design Concept -- Preliminary
On 20 Sep 2006 04:28:52 -0700, "Telstar Electronics"
wrote: +++Steveo wrote: +++ Are FET's the most economical transistors, or are are there other choices +++ for a 10 meter portable amp? The high drive would make it a bit more legal +++ too, wouldn't it? (dunno, just curious) +++ +++FETs like the MRF173 (or similar) have certain advantages. They also +++have several disadvantages... one is cost! Franks proposed design +++already looks to have a hefty price tag as described. +++ +++www.telstar-electronics.com ********** Prefer FETs even with their cost. They suffer less from thermal runaway as bipolar designes do. Bias network is easier to design. Major disadvantage to FETS are the inputs are very static sensitive. SO some means of ESD protection is needed that wont h inder RF performance. james |
Amp Design Concept -- Preliminary
On 20 Sep 2006 06:56:50 -0700, "Telstar Electronics"
wrote: +++Frank Gilliland wrote: +++ That's because I don't make cheap, disposable crap. Never have, never +++ will. But the use of FET's is at the discretion of the builder. The +++ amp can be built with either FET's or bipolars. No other modifications +++ are necessary, just a variation in the initial alignment. +++ +++Let me get this straight...swapping FETs with bi-polars in the +++design... and no modifications are necessary??? +++Get real... there are impedance matching issues, possibly B+ sources +++level differences, as well as well as totally different biasing +++circuitry. You are going to bias Frank?... right? +++ +++www.telstar-electronics.com *********** His modular design will allow for bias network to change versus technology. Input/output impedances for bipolar and FETS do not differ that much for equal power out and drive conditions. FETS do tend to be slightly higher though. Also his output module should be adjustable enough to compensate for these variances. james |
Amp Design Concept -- Preliminary
james wrote: Prefer FETs even with their cost. They suffer less from thermal runaway as bipolar designes do. Bias network is easier to design. Major disadvantage to FETS are the inputs are very static sensitive. SO some means of ESD protection is needed that wont h inder RF performance. But what about B+ requirements... power FETs are usually 28V or higher... while the bipolar allows for mobile use at much lower voltages. The FETs are also cost prohibitive as far as I'm concerned. www.telstar-electronics.com |
Amp Design Concept -- Preliminary
On Wed, 20 Sep 2006 15:00:51 GMT, james wrote
in : On Tue, 19 Sep 2006 14:31:52 -0700, Frank Gilliland wrote: +++ +++Enough of that cheap one-board crap..... this amp is MODULAR! +++ +++Modular design allows easy repair and modification, as well as ease of +++construction and interchangeability between different amps. It also +++allows seperation of functions both electronically and physically. The +++modules include: +++ +++* Input module. Includes variable attenuator and dummy load which +++provides adjustment of input power without 'tweaking' anything inside +++the radio. +++ ************* An attenuator on the input is nice. I am not sure a variable one is needed. By variable a multistep attenuator with four to six different values of attenuation would be a sufficient. A capability to switch the input drive to a internal du mmy load would nice luxury item but not necessary. There are two reasons for a variable attenuator. First, it allows the user to adjust the input power to achieve the best output power for the transistors being used. Second, the circuit is physically smaller than a stepped attenuator. The dummy load can also be external if the driver is more than a few watts. +++* Control module. Board that controls keying, bias & cooling fan. +++ +++* Sensor module. Board with circuits that take measurements from +++various locations throughout the amp and sends them to a meter. Meter +++function selection can be by rotory switch or by LCD display simply by +++swapping the board (module). Meter functions may include: +++ ***************** Man talk about monitoring circuits. Nice thing to have on a high tier amp. In reality most of these are great for development and early testing. Actual production would cause product cost to sky rocket. The idea here is to show all the possibilities, not necessarily to include all of them. Regardless, a sensor module could be built that -does- include all of them. And the rest of the amp will be designed with numerous test points that can easily be tapped for use by the sensor module, or just used for occasional service and calibration. There is one major advantage of having lots of measurements available at the front panel: it provides an opportunity for non-technical users to learn more about the internal operation of the amp, and therefore the best way to use it. So it could be a great educational tool for a classroom, or maybe even a ham. snip +++* Power Amplifier Module. The module will consist of the amplifier +++circuit, heat sink and cooling fan, constructed inside an enclosed +++sub-chassis designed for forced-air cooling. Flying in the face of +++convention, the power amplifier circuit will -not- be mounted on a PC +++board. Instead, the components will be chassis-wired with heavy-guage +++copper, except for the transistors which will be wired with strips of +++copper sheet having rounded edges and corners. This allows easy repair +++and modification, as well as more secure and robust connections. +++Circuit will be an ultra-linear, broadband, AB push-pull design +++(details at a later date). +++ **************** AIr dielectric striplines are nice for the power transistors. They do introduce some memchanical issues. Aint teflon great? It's almost too easy to drill a small hole in the strip and mount a teflon standoff. Heck of a lot easier than trying to design a board around the mounting feet. And strips allow a mechanical connection to the flags that's better than filling the gap between the flag and trace with solder. Great if you are in the 2KW or more output range. In the 100 to 250 watt range 2 ounce copper laminate would be quite sufficient. True, if you expect the transistors to never be replaced. But that's not the reality with CB amps. The owners like to swap transistors for more power. Either that, or they overdrive the transistors and blow them up. Replacing them tears up the board, which is why it's hard to find an old single-board amp with good traces. Point-to-point wiring eliminates this problem because both the transistors -and- the strips can be replaced. The servicable life of the amp is almost indefinite irrespective of the amount of work done to it. snip If you really want to go whole hog on the striplines then why not take the copper strips and either silver or gold plate them. Because it wouldn't last, and that's contrary to the concept behind the amp. Word of caution on gold over copper. Nickel is not a good conductor of RF. Nickel is usually plated onto copper to give gold a hard surface to plate to. Plating gold directly onto copper requires a much thicker plating so that the copper will not leach through the gold. Gold plating onto copper or brass is best done on top of a layer or two of silver. You can verify this with a call to your local trombone repair shop. snip ********************* Man after designing such a high tier amp, you adjust the bias through a panel hole with a screwdriver? Will you supply the gold plated screwdriver? It's not "high tier" at all. It's just moving the technology forward about 20 years or so (with 20-30 years of catch-up still to go). The boards are single-layer and can be fabricated at home with that cool laser-printer transfer stuff, the individual components are common and inexpensive (except maybe the power transistors), and the construction is both simple and flexible. The only major expense (other than the power transistors) is the labor. Just hire a few illegals and you have yourself a business! Or build it yourself with all the gold-plated frills and LCD sensor array if you want. Or build it one module at a time. Or buy the basic model and modify the modules as needed. It's all up to the builder. Yet despite all the possible variations, the basic design remains constant. That's the great part about a modular design. |
Amp Design Concept -- Preliminary
On 20 Sep 2006 09:06:03 -0700, "Telstar Electronics"
wrote in .com: james wrote: Prefer FETs even with their cost. They suffer less from thermal runaway as bipolar designes do. Bias network is easier to design. Major disadvantage to FETS are the inputs are very static sensitive. SO some means of ESD protection is needed that wont h inder RF performance. But what about B+ requirements... power FETs are usually 28V or higher... while the bipolar allows for mobile use at much lower voltages. Maybe you missed the part about the optional power supply. Go back and read it again. The FETs are also cost prohibitive as far as I'm concerned. I'm not suprised. |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
* Power supply module (optional). Power transistors that are designed for higher voltage are more linear and -much- more reliable than those designed to operate on 12-14 volts. This switching power supply bumps up the voltage to 28 or 50 VDC and allows the use of such transistors. Frank, just how much do you think this amp is going to cost? Sounds like It's going to be out of this world with all the stuff you are talking about... www.telstar-electronics.com |
Amp Design Concept -- Preliminary
On 20 Sep 2006 17:48:15 -0700, "Telstar Electronics"
wrote in .com: Frank Gilliland wrote: * Power supply module (optional). Power transistors that are designed for higher voltage are more linear and -much- more reliable than those designed to operate on 12-14 volts. This switching power supply bumps up the voltage to 28 or 50 VDC and allows the use of such transistors. Frank, just how much do you think this amp is going to cost? Sounds like It's going to be out of this world with all the stuff you are talking about... It will cost much more than you can afford on your budget, Brian. But if you -really- want one just wait a few years and maybe they'll start showing up at garage sales and thrift shops...... ok, probably not. But you can dream, right? |
Amp Design Concept -- Preliminary
Frank Gilliland wrote:
It will cost much more than you can afford on your budget, Brian. But if you -really- want one just wait a few years and maybe they'll start showing up at garage sales and thrift shops...... ok, probably not. But you can dream, right? I thought you were going to show me how to design a amp that was superior to mine... and was a product that was easily manufactured, repeatable, reliable, and profitable. Business-101 Frank. From what I can see of your design concept so far... you should reply... "none of the above"... LOL www.telstar-electronics.com |
Amp Design Concept -- Preliminary
On 21 Sep 2006 02:56:23 -0700, "Telstar Electronics"
wrote in .com: Frank Gilliland wrote: It will cost much more than you can afford on your budget, Brian. But if you -really- want one just wait a few years and maybe they'll start showing up at garage sales and thrift shops...... ok, probably not. But you can dream, right? I thought you were going to show me how to design a amp that was superior to mine... and was a product that was easily manufactured, repeatable, reliable, and profitable. Business-101 Frank. From what I can see of your design concept so far... you should reply... "none of the above"... LOL Repeatable -- Not only am I making the final design public, the entire process is going to be public domain. You, OTOH, won't even release your schematic for fear of constructive criticism. Reliable -- In case you haven't been paying attention, the fundamental concept of the design is longevity. These amps are going to be around and working long after you and your amps are dead and buried. Profitable -- I have saved the best for last. The -best- thing about a modular design is that it is perfectly LEGAL!!!. I can manufacture and market the chassis and modules independently under the premise that no component, in and of itself, constitutes an amplifier. The only way the government can touch this is if they outlaw every aspect of hobby electronics and the sale of each and every component, which we all know isn't going to happen (unless Bush declares a national emergency right after the 2008 election, refuses to give up his office, and installs a Republican dictatorship). There isn't one business-person on the planet that wouldn't invest in a business that can open up an entire market that was previously illegal. That, my friend, is called "profitable". But you go ahead and continue your work on your diminutive little amp, knowing that your market is limited in both scope and time. Feel free to waste your time on a product that will soon be without a market. The only thing you have going for you is the price.... but then again, have you done any market research lately? Do you know what people will pay for a decent amp? Probably not. But I have. So now that the cat's out of the bag, how hard are you going to fight this? Or would you rather buy into it and make a ****load of money? Feel free to email me with your answer. |
Amp Design Concept -- Preliminary
Frank Gilliland wrote: Repeatable -- Not only am I making the final design public, the entire process is going to be public domain. You, OTOH, won't even release your schematic for fear of constructive criticism. **Your statement here has nothing to do with having a repeatable design.** Reliable -- In case you haven't been paying attention, the fundamental concept of the design is longevity. These amps are going to be around and working long after you and your amps are dead and buried. **This is all talk right now. The fact that you will be using components such as connectors for board-to-board interfacing does not lend itself to high reliability.** Profitable -- I have saved the best for last. The -best- thing about a modular design is that it is perfectly LEGAL!!!. I can manufacture and market the chassis and modules independently under the premise that no component, in and of itself, constitutes an amplifier. The only way the government can touch this is if they outlaw every aspect of hobby electronics and the sale of each and every component, which we all know isn't going to happen (unless Bush declares a national emergency right after the 2008 election, refuses to give up his office, and installs a Republican dictatorship). There isn't one business-person on the planet that wouldn't invest in a business that can open up an entire market that was previously illegal. That, my friend, is called "profitable". **Again, nothing but talk and very premature... you have no design yet to base any profitability claims.** www.telstar-electronics.com |
Amp Design Concept -- Preliminary
On a sunny day (Thu, 21 Sep 2006 03:53:36 -0700) it happened Frank Gilliland
wrote in : knowing that your market is limited in both scope and time. Feel free to waste your time on a product that will soon be without a market. The only thing you have going for you is the price.... but then again, have you done any market research lately? Do you know what people will pay for a decent amp? Probably not. But I have. So now that the cat's out of the bag, how hard are you going to fight this? Or would you rather buy into it and make a ****load of money? Feel free to email me with your answer. There is a problem here with 'profit'. I just had a look at where I bought some other stuff, what amplifiers here go for: 100W MOSFET 42 Euro and 86 cent ( 54 $ and 44 cent). 500W 242 Euro and 93 cent (308 $ and 58 cent). 1000W 660 Euro and 15 cent (838 $ and 55 cent). Will indeed be hard to make any $$$$ on 100W amps. Not so different in the US I think, 1700W 650$: http://www.amateurlinearamplifiers.c...ce=hotproducts 500W 329$ http://www.amateurlinearamplifiers.c...ce=hotproducts I cannot make 100W for 54$, and I cannot make 1700W for 650$...... You have to count the hours too. Telstar has been at it now for years..... At 4$ profit per amplifier you'd have to sell zillions. :-) OTOH as a learning exercise making them was great. Just that I stopped when they were at in the street with the radio car to arrest me, spotted them just in time.... OK maybe I had some harmonics... and one licensed amateur was upset.... when he did see me with those big toobes. 'If I hear you I will turn you in'. He was later overrun by a car IIRC. It somehow strengthened my faith in God. But that is all of the past, and not on 27MHz. Honestly. Damn are we honest today. |
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