|
This FARA amp is a very nice, well behaved amp with constant (with frequency) gain¡ of course due to the fact that it uses ¡°real RF transistors¡± instead of motor current switches (AKA IRF510s) with input capacitance that varies sharply with frequency.? There are some larger RF transistors very similar to the 2312¡¯s that could easily be adapted to this circuit to give over 100 watts out. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? ? email:? bill@... ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of M Garza
Sent: Wednesday, January 10, 2018 2:53 PM
To: [email protected]
Subject: Re: [BITX20] Amplifier Kit? ? Has anyone built the FARA Amplifier?? Any thoughts on it?? It uses a pair of 2SC2312 bipolar transistors. Here is a link for a pdf:? I have a few HG 2SC2312s, so I am debating on ordering a couple of the board sets from FAR Circuits.? ?$18 for the 2 board set. ? On Wed, Jan 10, 2018 at 2:18 PM, kc0wox Leeper <kc0wox@...> wrote: You can see a youtube video testing the wa2eby amplifier lowpass filter frequency response at It uses a HP8407a network analyzer to check the frequency response. The first part of the video explains how a network analyzer works and then tests the lowpass filters.
Leonard
kc0wox
?
|
?
On Wednesday, January 10, 2018 8:18 PM, KC9SGV <kc9sgv@...> wrote:
This is probably all you need. I built one. It has about 10 SMD components to solder in... Still testing it, but it works ok so far.
KC9SGV
Sent from my iPad
On Jan 10, 2018, at 5:07 PM, chris gress < Chrisg0wfh@...> wrote: Any of you guys tried HFR-20w from Eleflow supposed to be 2sc1969 equivalent transistors made under licence I got them for a sgc2020 but was never used chris
|
This is probably all you need. I built one. It has about 10 SMD components to solder in... Still testing it, but it works ok so far.
KC9SGV
Sent from my iPad
toggle quoted message
Show quoted text
On Jan 10, 2018, at 5:07 PM, chris gress < Chrisg0wfh@...> wrote: Any of you guys tried HFR-20w from Eleflow supposed to be 2sc1969 equivalent transistors made under licence I got them for a sgc2020 but was never used chris
|
Any of you guys tried HFR-20w from Eleflow supposed to be 2sc1969 equivalent transistors made under licence I got them for a sgc2020 but was never used chris
On 10 Jan 2018 21:49, "M Garza" < mgarza896@...> wrote: I have been purchasing MRF477s, 2SC2312s, and 2SC1969s directly from HG semiconductor (). ? I have a HTX-10 and a couple of HTX-100s that I repaired with the parts.? The parts work well and are direct drop in replacements.? The repairs have all been 10M radios, so I want to see if they work in a push-pull amp.?? I also would not mind putting together a 50 watt MRF477 push-pull amp (1995 Handbook, page 17.93).
Marco - KG5PRT
|
I have been purchasing MRF477s, 2SC2312s, and 2SC1969s directly from HG semiconductor ().? I have a HTX-10 and a couple of HTX-100s that I repaired with the parts.? The parts work well and are direct drop in replacements.? The repairs have all been 10M radios, so I want to see if they work in a push-pull amp.?? I also would not mind putting together a 50 watt MRF477 push-pull amp (1995 Handbook, page 17.93).
Marco - KG5PRT
On Wed, Jan 10, 2018 at 3:15 PM, Thomas Sharka via Groups.Io <sharkatw@...> wrote: The 2SC2312 is long out of manufacture so any "new" ones that you find on ebay will most likely be factory sweepings that were relabled. While it's possible to stress test each and every one that you purchase, there won't be a reliable run to be found. ? But if you enjoy the thrill of finding a suitable substitute, I don't see anything wrong with the design. It's simple and straightforward. You have to be careful not to overdrive it, however as it will probably fry those finals in a very short time. Also, the max ratings on the transistor are about 17 watts each, so if you're driving a pair at 40 watts, you're going to be pushing them a bit.
Sent from Yahoo Mail.
On Wednesday, January 10, 2018 3:53 PM, M Garza <mgarza896@...> wrote:
Has anyone built the FARA Amplifier?? Any thoughts on it?? It uses a pair of 2SC2312 bipolar transistors. Here is a link for a pdf:? I have a few HG 2SC2312s, so I am debating on ordering a couple of the board sets from FAR Circuits.? ?$18 for the 2 board set.
|
Um No. ?ALC was designed for limiting catastrophic over drive situations from occurring, not to use as gain control. ?The feedback loop turns your otherwise linear amplifier into a non-linear amplifier generating all sorts of bad byproducts.?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it:
email:??bill@... ?
toggle quoted message
Show quoted text
On Jan 10, 2018, at 2:38 PM, Vince Vielhaber < vev@...> wrote: Another option would be ALC like on commercially made rigs.Vince.On 01/10/2018 11:51 AM, Diver Martin wrote:The biggest problem to adding an amp to the uBitx is the fact that it's
using the IRF510's as the output amplifier, and the output power is not
consistent. ?I've thought about adding my 50W amplifier to the uBitx,
but the issue there is that the amplifier only needs 0.7W drive at 40m,
and needs 3W drive at 10m. ?The uBitx is putting out 7-10W @ 40m, and
under 3W at 10m, so a variable attenuator or something would be needed,
or a set of attenuation resistors and switches.
One option might be to reduce the gain (Increase negative feedback) of
the output amplifier using R261/R262 which are pretty large at 200 ohms,
and increasing the input drive. ?I haven't experimented with this yet
though, and they'd probably have to be beefier resistors. ?All things in
due time, my mod PCB project comes first (it's almost done, will
hopefully send out a preliminary design email tonight).
On Wed, Jan 10, 2018 at 8:44 AM, Rob N4RMK <N4RMK.tn@...
<mailto:N4RMK.tn@...>> wrote:
???I'm a total novice with electronics, so I'm not sure whether I could
???effectively make this mod. ?I'm just thinking that a 50 watt or 100
???watt amp would be an awesome addition to the uBitx.
--
Martin Held - AE7EU
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?
-- ?Michigan VHF Corp. ?? ?? ?????????????????????????
|
The 2SC2312 is long out of manufacture so any "new" ones that you find on ebay will most likely be factory sweepings that were relabled. While it's possible to stress test each and every one that you purchase, there won't be a reliable run to be found. ? But if you enjoy the thrill of finding a suitable substitute, I don't see anything wrong with the design. It's simple and straightforward. You have to be careful not to overdrive it, however as it will probably fry those finals in a very short time. Also, the max ratings on the transistor are about 17 watts each, so if you're driving a pair at 40 watts, you're going to be pushing them a bit.
Sent from Yahoo Mail.
On Wednesday, January 10, 2018 3:53 PM, M Garza <mgarza896@...> wrote:
Has anyone built the FARA Amplifier?? Any thoughts on it?? It uses a pair of 2SC2312 bipolar transistors. Here is a link for a pdf:? I have a few HG 2SC2312s, so I am debating on ordering a couple of the board sets from FAR Circuits.? ?$18 for the 2 board set.
On Wed, Jan 10, 2018 at 2:18 PM, kc0wox Leeper <kc0wox@...> wrote: You can see a youtube video testing the wa2eby amplifier lowpass filter frequency response at It uses a HP8407a network analyzer to check the frequency response. The first part of the video explains how a network analyzer works and then tests the lowpass filters.
Leonard
kc0wox
|
Thanks! That German project is interesting too.
Vince.
toggle quoted message
Show quoted text
On 01/10/2018 02:32 PM, AndyH wrote: Vince - on 40 meters the prototype WA2EBY drew about 4A from 28V.
Both of the original QST articles are here (in English) along with a
100W variant (in German):
Andy
On Wed, Jan 10, 2018 at 10:46 am, Vince Vielhaber wrote:
They say the EBY amp puts out 40 watts with a 28v supply. What's the
current draw on that?
Vince.
--
Michigan VHF Corp.
|
Has anyone built the FARA Amplifier?? Any thoughts on it?? It uses a pair of 2SC2312 bipolar transistors. Here is a link for a pdf:? I have a few HG 2SC2312s, so I am debating on ordering a couple of the board sets from FAR Circuits.? ?$18 for the 2 board set.
On Wed, Jan 10, 2018 at 2:18 PM, kc0wox Leeper <kc0wox@...> wrote: You can see a youtube video testing the wa2eby amplifier lowpass filter frequency response at It uses a HP8407a network analyzer to check the frequency response. The first part of the video explains how a network analyzer works and then tests the lowpass filters.
Leonard
kc0wox
|
|
|
Another option would be ALC like on commercially made rigs.
Vince.
toggle quoted message
Show quoted text
On 01/10/2018 11:51 AM, Diver Martin wrote: The biggest problem to adding an amp to the uBitx is the fact that it's
using the IRF510's as the output amplifier, and the output power is not
consistent. I've thought about adding my 50W amplifier to the uBitx,
but the issue there is that the amplifier only needs 0.7W drive at 40m,
and needs 3W drive at 10m. The uBitx is putting out 7-10W @ 40m, and
under 3W at 10m, so a variable attenuator or something would be needed,
or a set of attenuation resistors and switches.
One option might be to reduce the gain (Increase negative feedback) of
the output amplifier using R261/R262 which are pretty large at 200 ohms,
and increasing the input drive. I haven't experimented with this yet
though, and they'd probably have to be beefier resistors. All things in
due time, my mod PCB project comes first (it's almost done, will
hopefully send out a preliminary design email tonight).
On Wed, Jan 10, 2018 at 8:44 AM, Rob N4RMK <N4RMK.tn@...
<mailto:N4RMK.tn@...>> wrote:
I'm a total novice with electronics, so I'm not sure whether I could
effectively make this mod. I'm just thinking that a 50 watt or 100
watt amp would be an awesome addition to the uBitx.
--
Martin Held - AE7EU
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?
--
Michigan VHF Corp.
|
You can see a youtube video testing the wa2eby amplifier lowpass filter frequency response at It uses a HP8407a network analyzer to check the frequency response. The first part of the video explains how a network analyzer works and then tests the lowpass filters.
Leonard
kc0wox
|
Vince - on 40 meters the prototype WA2EBY drew about 4A from 28V.
Both of the original QST articles are here (in English) along with a 100W variant (in German):?
Andy
toggle quoted message
Show quoted text
On Wed, Jan 10, 2018 at 10:46 am, Vince Vielhaber wrote:
They say the EBY amp puts out 40 watts with a 28v supply. What's the
current draw on that?
Vince.
|
Rob,
? ?I can also recommend the WA2EBY linear - it works great with my BITX40v3 using a 7dB pad.? The next linear I'll build is the EB63A from Communication Concepts.? It's been confirmed to work with a number of QRP rigs including various BITXs.? Like the WA2EBY amp, it has an RF-operated keying relay circuit so requires no radio mods.
? ?If you decide on the WA2EBY amp, I suspect you'll find it to be a beginner-friendly project.? It's easy to build and adjust, especially with Leonard, KC0WOX's parts list, source links, and build instructions.? His Mouser project list covers all of the parts.? While a couple of the specific numbers are obsolete, Mouser has plenty of replacements.? When I load the list today, I see that we need an alternative for a 500V mica cap, an SMD cap, and a relay snubber diode.
The diode can be any 1N4004 or similar.
? ?
? ? Best,
? ? ?Andy, KG5RKP
toggle quoted message
Show quoted text
On Wed, Jan 10, 2018 at 07:13 am, Rob N4RMK wrote:
I hope this isn¡¯t too far off-topic to ask here. ?I¡¯ve looked for an amplifier kit similar to the Bitx radio. ?Does anyone here know of such a kit? ?
de N4RMK?
|
They say the EBY amp puts out 40 watts with a 28v supply. What's the current draw on that?
Vince.
toggle quoted message
Show quoted text
On 01/10/2018 10:24 AM, N8DAH wrote: Only ones I know of are the Hardrock-50, HFpacker and the WA2EBY. All
but the last one are total kits and cost 300+
I just built up a WA2EBY amp and am pretty happy with it so far.
I got the pcb's from
Toroids
Build notes
I would suggest if you choose the WA2EBY option be sure to do a proper
parts list as the on from the link in the build notes is a bit outdated.
73
GL
David
N8DAH
--
Michigan VHF Corp.
|
Seems acceptable to twiddle RV1 (or some sort of mike audio gain) when switching bands, given the $120 price.?
Though we need a convenient way to indicate how far to twiddle.
Adding negative feedback as per post 38817 to the existing uBitx final,
then driving that reduced but consistent output into something like the WA2EBY is also a good option.
Jerry, KE7ER
toggle quoted message
Show quoted text
On Wed, Jan 10, 2018 at 09:24 am, M Garza wrote:
I guess it would be more like a 4P switch, 2 for the input pads and 2 for the LPFs.
You could also use relays. The switch would just turn on the appropriate relays.
?
|
I guess it would be more like a 4P switch, 2 for the input pads and 2 for the LPFs. You could also use relays. The switch would just turn on the appropriate relays.
Just thinking out loud.
Marco - KG5PRT
On Wed, Jan 10, 2018 at 11:19 AM, M Garza <mgarza896@...> wrote: Here is an idea for the variable input pad control: Since you are probably going to have a rotary switch to select the correct LPF, use a double pole rotary switch.? 1 pole controls the LPF and the other selects the correct input pad.?? Yes, it makes the part count increase, but it is only a few more resistors.
Just an idea.
Marco - KG5PRT
|
Hobbypcb has a 5 watter that's pretty good.
TAPPR (?) has a 20 watt unit
I've built both the above and they are good amps.
Lots of them from 5 to 50 watts, $20 to $300
PJH, N7PH
|
Here is an idea for the variable input pad control: Since you are probably going to have a rotary switch to select the correct LPF, use a double pole rotary switch.? 1 pole controls the LPF and the other selects the correct input pad.?? Yes, it makes the part count increase, but it is only a few more resistors.
Just an idea.
Marco - KG5PRT
On Wed, Jan 10, 2018 at 10:51 AM, Diver Martin <diver.martin@...> wrote: The biggest problem to adding an amp to the uBitx is the fact that it's using the IRF510's as the output amplifier, and the output power is not consistent.? I've thought about adding my 50W amplifier to the uBitx, but the issue there is that the amplifier only needs 0.7W drive at 40m, and needs 3W drive at 10m.? The uBitx is putting out 7-10W @ 40m, and under 3W at 10m, so a variable attenuator or something would be needed, or a set of attenuation resistors and switches.
One option might be to reduce the gain (Increase negative feedback) of the output amplifier using R261/R262 which are pretty large at 200 ohms, and increasing the input drive.? I haven't experimented with this yet though, and they'd probably have to be beefier resistors.? All things in due time, my mod PCB project comes first (it's almost done, will hopefully send out a preliminary design email tonight).
|
The biggest problem to adding an amp to the uBitx is the fact that it's using the IRF510's as the output amplifier, and the output power is not consistent.? I've thought about adding my 50W amplifier to the uBitx, but the issue there is that the amplifier only needs 0.7W drive at 40m, and needs 3W drive at 10m.? The uBitx is putting out 7-10W @ 40m, and under 3W at 10m, so a variable attenuator or something would be needed, or a set of attenuation resistors and switches.
One option might be to reduce the gain (Increase negative feedback) of the output amplifier using R261/R262 which are pretty large at 200 ohms, and increasing the input drive.? I haven't experimented with this yet though, and they'd probably have to be beefier resistors.? All things in due time, my mod PCB project comes first (it's almost done, will hopefully send out a preliminary design email tonight).
On Wed, Jan 10, 2018 at 8:44 AM, Rob N4RMK <N4RMK.tn@...> wrote: I'm a total novice with electronics, so I'm not sure whether I could effectively make this mod.? I'm just thinking that a 50 watt or 100 watt amp would be an awesome addition to the uBitx.
-- Martin Held - AE7EU
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?
|
K9HZ