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Author Topic: 10 meter mobile amp  (Read 8944 times)
W8GU
Member

Posts: 2




Ignore
« on: November 05, 2012, 04:55:19 PM »

OK.  Don't want to be a lightning rod.  
Not looking for a CB 'linear' amplifier.

I picked up an old Uniden HR2600 at a hamfest about a week ago to use in the car.  I have been having a lot of fun lately on 15 and 10, and I have more time in the car than I do at home, so it just made sense.

I would like to beef up the output of unit, but I don't want to buy an illegal CB linear because from what I hear they are mostly nonlinear linears.  I want a nice clean signal.

I have looked around and mostly what I see when someone asks about a 10 meter mobile amplifier is screaming that the CB amplifiers are bad.  I know this.  If that is all you have to say, please don't respond to this message.

So, does anyone have any suggestions?
My criteria:
- affordable
- small
- runs on 12 volts nominal
- takes 25 watts or so PEP SSB input
- clean signal
- A kit would be WONDERFUL
- Plans with a PC board would be WONDERFUL
- Output of 100 Watts PEP would be desirable

Thanks,
Mark
W8GU
« Last Edit: November 05, 2012, 05:00:05 PM by W8GU » Logged
K6LO
Member

Posts: 226




Ignore
« Reply #1 on: November 05, 2012, 05:22:52 PM »

Have a search of the QST archives. You may find just what you need.

73, Luke
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W9GB
Member

Posts: 2623




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« Reply #2 on: November 05, 2012, 06:16:47 PM »

Mark -

Small HF amplifiers in this class have been offered by Kenwood and Yaesu in the past (1970s, 1980s).
The higher costs of these amps were associated with providing the proper filtering, band switching, and heat sink sizing.

Virgil Stamps, K5OOR provides a set of kits for the DIY builder.  
http://site.hfprojectsyahoo.com/home

You will note that they are BAND Switchable.
http://site.hfprojectsyahoo.com/hf_packer-amp
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KW6LA
Member

Posts: 92




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« Reply #3 on: November 05, 2012, 07:27:16 PM »

http://www.w8ji.com/rm_hla-150_test.htm

Take a look at this . If you use a monoband antenna and not over drive it, might be what you’re looking for. Tom said it passed holding his noise !

GL-   KW6LA
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W8JX
Member

Posts: 5791




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« Reply #4 on: November 06, 2012, 06:33:03 AM »

Honestly when 10 is open you do not need a amp. I never used my amp up there. That band is very QRP friendly.
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KB1GMX
Member

Posts: 773




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« Reply #5 on: November 06, 2012, 01:32:24 PM »

The problem is 25watts is too much drive for amps under 300W.

The next one is to make it worth your time 100W minimum (most only want a few watts drive).

Anything over 100-150W output will suck current like mad (think #4 gauge or heavier
cables to battery).

I assume your using a full size whip (about 96-100inches). If not that would buy you more
with less pain.


Allison
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WX7G
Member

Posts: 6052




Ignore
« Reply #6 on: November 06, 2012, 01:44:55 PM »

Have you considered selling the Uniden and buying a 100 watt transceiver?
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W8GU
Member

Posts: 2




Ignore
« Reply #7 on: November 06, 2012, 04:48:11 PM »

Well, first let me say that I am very pleased with the responses I have received.
I have researched some of them, but I have a lot of work before I decide.
I appreciate all of the help.

Luke, K6LO, that is a great idea.  I have started from 2011 working backwards.  A lot of interesting reading.

W9GB, thanks.  I would prefer a Yaesu or Kenwood unit from the 70's or 80's.  My home rig is a FT-301 with the booster unit on the back.  I guess if there was something like that booster unit out there, followed by a filter on the output, that would feel very comfortable to me.

The K5OOR unit sounds interesting, but I was hoping for something a little more affordable.

KW6LA, I might consider that unit.  I was surprised to see it listed on newegg.com.  I am not sure that I am comfortable with the level of linearity, but it is not too bad.

W8JX, you are right, but when the band is open and there is DX out there, sometimes a little more power makes a much better overall experience.  I would like the option to QRO when I need to do so to make a contact.

KB1GMX, interesting analysis.  I need to think about all of what you said for a while.  As for my antenna, I am working on that.  Right now, I am just using a Larsen NMO27, and that can certainly be improved.

WX7G, I got the uniden because i have been focusing on affordability.  Maybe penny wise, but I am a cheap ham.  That is part of the fun of it.

Thanks to all
Mark
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KW6LA
Member

Posts: 92




Ignore
« Reply #8 on: November 06, 2012, 04:53:43 PM »

These are comments well said, however you can adjust the drive of the HR 2600. I had a HR 2510 years back and did the same thing with a amplifier, but it’s a crappy radio !
Full ¼ wave whip is great way to operate Ten meters.  Shame to say it did feed my ego to QRO to 400 pep to break a pile up. If you build QRP rigs and operate them like I do,
It’s nice to have a amp to use when QRP is not viable. Otherwise save your money and buy a better radio with 100 or 200 pep output. To many Hams buy it 3 or more times till
they get it right !

KW6LA-
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KG4FET
Member

Posts: 26




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« Reply #9 on: November 09, 2012, 06:23:52 AM »

There is an add on 100 watt amp out there on Fleabay.  There is also a mod to replace the obsolete finals with a single MFR 455 final in the 2510/26000 on Rogerbirds web site, the President Lincoln had this done to it already so there is a president. This will give you in the neighborhood of 80 watts output pep.
73 es Good Luck
DE KG4FET Sandor
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KC4MOP
Member

Posts: 734




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« Reply #10 on: November 12, 2012, 05:09:56 PM »

These are pretty nice amps.
I have a smaller one from them that puts out 200W using AM or 400W SSB......
I do not push it hard (over drive)

http://www.rmitaly.com/showproducts.asp?idgr=1&cat=0&NumPagRec=1

And there are some RM Italy amps on fleebay. The link above is their website.
Fred
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ZENKI
Member

Posts: 935




Ignore
« Reply #11 on: November 16, 2012, 12:31:15 AM »

All really poor CB rubbish that does not belong on the ham bands.

Why any ham would want to use this CB garbage on the ham bands in the form of   splattering CB amplifiers and freeband CB radios with poor IMD suppression is beyond belief. There  are so many affordable genuine ham radios
available that perform much better and cost less. A second point is that the economics of buying a freeband radio and  crap CB amplifier dont add up when you can buy a proper 100 watt transceiver like the IC718 for much less money.
The operating ergonomics  is certainly superior. I guess you cant take the CB'er out of some hams. It seems many CB'ers who become hams dont want to give up their ignorant  ways and poor equipment.

Leave the CB junk up on the CB bands not on the ham bands.

 Hams who use this type equipment stand out like sore thumb on the ham bands because of the interference that they cause.  It seems many hams who use this equipment suffer from technical deficit disorder, it seems that there is no cure for this malaise.



These are pretty nice amps.
I have a smaller one from them that puts out 200W using AM or 400W SSB......
I do not push it hard (over drive)

http://www.rmitaly.com/showproducts.asp?idgr=1&cat=0&NumPagRec=1

And there are some RM Italy amps on fleebay. The link above is their website.
Fred
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K2FOX
Member

Posts: 110




Ignore
« Reply #12 on: November 17, 2012, 08:28:42 PM »

All really poor CB rubbish that does not belong on the ham bands.

Why any ham would want to use this CB garbage on the ham bands in the form of   splattering CB amplifiers and freeband CB radios with poor IMD suppression is beyond belief. There  are so many affordable genuine ham radios
available that perform much better and cost less. A second point is that the economics of buying a freeband radio and  crap CB amplifier dont add up when you can buy a proper 100 watt transceiver like the IC718 for much less money.
The operating ergonomics  is certainly superior. I guess you cant take the CB'er out of some hams. It seems many CB'ers who become hams dont want to give up their ignorant  ways and poor equipment.

Leave the CB junk up on the CB bands not on the ham bands.

 Hams who use this type equipment stand out like sore thumb on the ham bands because of the interference that they cause.  It seems many hams who use this equipment suffer from technical deficit disorder, it seems that there is no cure for this malaise.

From the man with a CB HANDLE for a screen name. LOL!
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KB1GTX
Member

Posts: 459




Ignore
« Reply #13 on: November 17, 2012, 10:48:13 PM »

More time than not the difference between a cb garbage amp and many older ham set final amps is just a few ma of bias on the bases on the transistors.
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YO9IRF
Member

Posts: 29


WWW

Ignore
« Reply #14 on: November 18, 2012, 01:40:03 AM »

All really poor CB rubbish that does not belong on the ham bands.

Why any ham would want to use this CB garbage on the ham bands in the form of   splattering CB amplifiers and freeband CB radios with poor IMD suppression is beyond belief. There  are so many affordable genuine ham radios
available that perform much better and cost less. A second point is that the economics of buying a freeband radio and  crap CB amplifier dont add up when you can buy a proper 100 watt transceiver like the IC718 for much less money.
The operating ergonomics  is certainly superior. I guess you cant take the CB'er out of some hams. It seems many CB'ers who become hams dont want to give up their ignorant  ways and poor equipment.

Leave the CB junk up on the CB bands not on the ham bands.

 Hams who use this type equipment stand out like sore thumb on the ham bands because of the interference that they cause.  It seems many hams who use this equipment suffer from technical deficit disorder, it seems that there is no cure for this malaise.


You need to understand the purpose of each equipment first, then start calling it "junk" or otherwise. A transmitter made to run on mobile, on a monoband resonant antenna and with 10KHz spacing between channels won't be as clean in IMD and harmonics as a transmitter made for the ham bands, of course; that doesn't mean it's junk, just that it was made for another purpose, where it may do it's job very well. Also, the CB mobile amplifiers are running in class-C because they're made for FM, and certain designs can meet ERP harmonics requirements even without amplifier output filters; the equipment is not necessarily junk, it's designed for another purpose.

The person that uses such equipment in another way that it was intended to, well, that is the real problem. A "500W" CB amplifier usually uses a pair of transistors that can actually put out less than 300W in total, and to be SSB IMD compliant you need to modify it to class AB and run it at below 200W out. It's specs will stand up to any decent ham amplifier this way, but it makes no sense in getting such a thing as long as you already have reasonably priced ham transcievers out there that put out 100W.

@ Mark W8GU: from 25W to 100W you have a 6dB increase, that is a single S-unit at the recieving station. In my opinion it's not worth it to go trough the trouble for only that much; you would first need to go for the best antenna you can use, than start thinking about more power - and when you do, go for something around 300W, otherwise you won't even notice the improvement. Plus there is the problem of not overdriving the amplifier, usually amps have around 10-13dB gain (5-10W input > 100W output), if you want to drive a 100W amplifier with 25W you'll have to either add an attenuator (one that can handle 25W will get hot, needs a radiator, box and RX/TX switch of it's own, adds to the price) or turn down the transciever output power, wich may kill the amplifier by overdriving if you accidentally forget to turn it down everytime you switch the amp on, or the transciever may spike on TX (ouputs max power for a very short time even if power it's turned down).
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