Linear amplifiers for UBITX6 and other QRP transceivers...


Dan Eggers N7DE
 

I have attached a copy of what is more or less my report about the available linear amplifiers for QRP transceivers as well as some additional reference material.

       73, Dan Eggers, N7DE
              P.O. Box 751
              Edinburg, TX 78540-0751


Max
 

Looking at the XDT-LPF200 filter, are the caps on the back side of the board? I don't see any on the top side.

I don't understand why some of these amp don't cover 80/75 meters. Thunder storms can make a lot of noise on that band.

Max KG4PID

p.s. Thanks for sharing you finding.



On Wednesday, November 9, 2022, 04:42:23 PM CST, Dan Eggers N7DE <n7de@...> wrote:


I have attached a copy of what is more or less my report about the available linear amplifiers for QRP transceivers as well as some additional reference material.

       73, Dan Eggers, N7DE
              P.O. Box 751
              Edinburg, TX 78540-0751


ajparent1/kb1gmx
 

Since i have a few of thse tje answer is they all cover 80m and some 160m. 


also I’ve used my EBY built back in the single digits
running 28v to 60w on 40, 20.  Mine does about
25w on 6m.  Transformer is not optimal there.  On 
10m i see 37w for 1.4w drive.

Most shown are not optimized or workable above 20 Mhz. 


--
Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

of all the amps mentioned the "70 watt" is both the worst and interesing.

ITs really 70W DC input maybe 35-40 out, least mine is.  Choice of
Mosfets used is poor and the transformer are far from optimum.
Result is power above 20M falls off rapidly with frequency.

The board when used with even IRF510s is better though
transformer optimization is required.

One note the best result with with RF grade devices
(gemini on single flange).  I made on up using MRF151G
I had looking for a home and with a Transformer described
by GFX back a few years in QEX makes a nice 300W @ 50V
good to 6M (290W).  Not for the average builder.

Allison
------------------
Please use the forum, offline and private will go to bit bucket.


Ashhar Farhan
 

Why don't you just use the sbitx amp? It has far better output in terms of being clean and it is sufficiently developed by now.


On Thu, Nov 10, 2022, 7:57 PM ajparent1/kb1gmx <kb1gmx@...> wrote:
of all the amps mentioned the "70 watt" is both the worst and interesing.

ITs really 70W DC input maybe 35-40 out, least mine is.  Choice of
Mosfets used is poor and the transformer are far from optimum.
Result is power above 20M falls off rapidly with frequency.

The board when used with even IRF510s is better though
transformer optimization is required.

One note the best result with with RF grade devices
(gemini on single flange).  I made on up using MRF151G
I had looking for a home and with a Transformer described
by GFX back a few years in QEX makes a nice 300W @ 50V
good to 6M (290W).  Not for the average builder.

Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

Talking to me?

Its not an issue for me, its the earlier part of this string talking about
potential uBitx/BITx useres that need amps.  That would be the go
from 2w out (or attenuated down to 2W)  to the  50 to 100W region.

Like I've said multiple times with a few watts I have amps already
completed that will do 50W (EBY) or 100W(MRF255x2).  One is now
(EBY) 17 years old and the other is working and tested.  They work
well with multiple radios like the FT817, and a few of my other
monobanders.

The others are experiments gone wild.

Allison
------------------
Please use the forum, offline and private will go to bit bucket.


Dan Eggers N7DE
 

I wish I had known about your amplifiers, because that would have saved me a lot of work.  

      73, Dan


From: BITX20@groups.io <BITX20@groups.io> on behalf of ajparent1/kb1gmx <kb1gmx@...>
Sent: Thursday, November 10, 2022 7:25 AM
To: BITX20@groups.io <BITX20@groups.io>
Subject: Re: [BITX20] Linear amplifiers for UBITX6 and other QRP transceivers...
 
Talking to me?

Its not an issue for me, its the earlier part of this string talking about
potential uBitx/BITx useres that need amps.  That would be the go
from 2w out (or attenuated down to 2W)  to the  50 to 100W region.

Like I've said multiple times with a few watts I have amps already
completed that will do 50W (EBY) or 100W(MRF255x2).  One is now
(EBY) 17 years old and the other is working and tested.  They work
well with multiple radios like the FT817, and a few of my other
monobanders.

The others are experiments gone wild.

Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

You compiled what is typical with average construction habits.  There is a lot of junk out there and most need help to understand the basics.

 
--
Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

Dan,

The nearly 100000 postings here can be farmed.
I mentioned the 'EBY amp here back in 2007 and many times since.

Generally there are a dozen or so topics that reappear every few
months or so and are in the wiki, files, and of course posting history.

Yet its incredibly rare any one looks.

Allison
------------------
Please use the forum, offline and private will go to bit bucket.


AndyH
 

A couple of shipments arrived today for a 100W MRF101A- based amp project. Appears to be another entry for the uBITX boots list.

https://sites.google.com/site/rfpowertools/rf-power-tools/nxp-mrf-101
https://hf5l.pl/en/amplifier-mfr101/

I like the Juma PA100-D - nicely engineered. But a number of parts are obsolete at this point, adding to the challenge.  Possibly still available from Romania, yet pricy.

http://www.jumaradio.com/juma-pa100/
https://rowaves.com/120%C3%B7300w/juma-pa-100d-160-10m-100w-linear-amplifier-digital-control/

Andy


ajparent1/kb1gmx
 

MRF101, hope you got the mechanical complments as it makes for good layouts. 

with a good ground plane and vhf layout there good to well above 6m.  The only yabut is 50V power. 


--
Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

All of the good 50v stuff barely wakes up with less than 40v.  The upside is they produce  very low imd.  Fairly hard to cook too.


Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

https://rowaves.com/120%C3%B7300w/juma-pa-100d-160-10m-100w-linear-amplifier-digital-control/

At 556.5 euro that amp better be gold plated, wow!

For under 3000$US you can get (if you wait) a KW scale amp (Mercury III).
Or maybe a Elecraft KXP500.


Allison
------------------
Please use the forum, offline and private will go to bit bucket.


Dan Eggers N7DE
 

I wanted to have an HF linear amplifier including the lowpass filter for $200 or less.  That is why I am interested in a 50-watt amplifier is because that saves about $200 of the cost.  I still haven't seen one yet other than the ones I have presented.  

I hope this is an OK compromise font.          73, Dan, N7DE
 

From: BITX20@groups.io <BITX20@groups.io> on behalf of ajparent1/kb1gmx <kb1gmx@...>
Sent: Saturday, November 12, 2022 9:34 AM
To: BITX20@groups.io <BITX20@groups.io>
Subject: Re: [BITX20] Linear amplifiers for UBITX6 and other QRP transceivers...
 
https://rowaves.com/120%C3%B7300w/juma-pa-100d-160-10m-100w-linear-amplifier-digital-control/

At 556.5 euro that amp better be gold plated, wow!

For under 3000$US you can get (if you wait) a KW scale amp (Mercury III).
Or maybe a Elecraft KXP500.


Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

Much better font size.

See the other posting on this topic.  Its getting hard to do that for 200$
maybe the basic amp sans packaging.  And likely trade bandwidth as
well.

Do not forget the MEF9120 is obsolete and the supply is from salvage
maybe a few ar NOS. So the price is at best a maybe.  It still a 28V part,
at nominal 13.8V expect maybe 20W, likely less.  MRF101, good part
same issues. only now 48V but you get 100W for the effort.


Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

Do search the net for the price of LPF for desired bands good for 50 or more watts.

The sell price may raise a eyebrows, and you get to wind them.

--
Allison
------------------
Please use the forum, offline and private will go to bit bucket.


Dan Eggers N7DE
 

Look at the 3 - 30 MHz XDT-LPF200 lowpass filter.  It performs very well, and the price is very reasonable for what you get.  My solution to the switching is 6 toggle switches, and the one in the up position is the band you are on.  That problem I have solved already.

To get the price down the user has to do some of the work, or have it done in India.  Drilling and tapping is a good skill to have, and you have to use sheet metal these days, because Aluminum has gone up so much in price that it is now out as a material.  Sheet metal you can cut with a pair of shears.

        73, Dan, N7DE
 

From: BITX20@groups.io <BITX20@groups.io> on behalf of ajparent1/kb1gmx <kb1gmx@...>
Sent: Saturday, November 12, 2022 12:18 PM
To: BITX20@groups.io <BITX20@groups.io>
Subject: Re: [BITX20] Linear amplifiers for UBITX6 and other QRP transceivers...
 
Do search the net for the price of LPF for desired bands good for 50 or more watts.

The sell price may raise a eyebrows, and you get to wind them.

--
Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

On Sat, Nov 12, 2022 at 12:29 PM, Dan Eggers N7DE wrote:
XDT-LPF200
I don't do fleabay.  I already have a few LPF modules from years ago, a good buy.

Toggle switches?  how about a nice 5 or 6 position switch.

As to the rest its your project so how you proceed is up to you.  I'd poll the
possible customer base as to what they want and would do.


Allison
------------------
Please use the forum, offline and private will go to bit bucket.


Dan Eggers N7DE
 

The XDT-LPF200 is very good.  I tested it with very fancy equipment in the Electrical Engineering Department at the University of Texas Rio Grande Valley, and it completely meets all FCC requirements.  The rest may be flea bay, but this is different, and it is very good at a low price.

 A nice 6 position switch is out, because of the cost.  They used to be $80 from MFJ, but I feel sure they would be $100 or more now, and that is just too much.

As far as polling the customer base goes the company that made the UBITX6 would need to poll the purchasers.  I have been using an MFJ 9040 and an MFJ 9020 CW transceivers for 19 years now, but I bought some students a UBITX6 to work with, because I liked the all in one, and additional bands to work with, and I would be happy to respond to a poll, but I do not think the company would give me the purchaser's information.  I think it would be wonderful if they contacted the customers about buying a WA2EBY amplifier, and that would get them into the ballpark. 

         73, Dan, N7DE




From: BITX20@groups.io <BITX20@groups.io> on behalf of ajparent1/kb1gmx <kb1gmx@...>
Sent: Saturday, November 12, 2022 2:34 PM
To: BITX20@groups.io <BITX20@groups.io>
Subject: Re: [BITX20] Linear amplifiers for UBITX6 and other QRP transceivers...
 
On Sat, Nov 12, 2022 at 12:29 PM, Dan Eggers N7DE wrote:
XDT-LPF200
I don't do fleabay.  I already have a few LPF modules from years ago, a good buy.

Toggle switches?  how about a nice 5 or 6 position switch.

As to the rest its your project so how you proceed is up to you.  I'd poll the
possible customer base as to what they want and would do.


Allison
------------------
Please use the forum, offline and private will go to bit bucket.


ajparent1/kb1gmx
 

I was not talking about a mfj band switch.  

just a inexpensive 6 pole dwitch that gors for a few dollars. 


--
Allison
------------------
Please use the forum, offline and private will go to bit bucket.