Building an HT amp

[KD0RVY]

So I currently have my Wouxun KG-UV6D and I would like to build an amp for it. I'm thinking something since the radio is 5w, I would want to do 5w in and then be able to get it up to 30w-50w or so. I have been doing a lot of looking and I am just not finding anything yet. I would like a kit that is very compact, maybe even Altoid tin size if possible, and would be easy to put together. Doe's anyone in here know of any great kits or where I could look to get such a kit? Thank you all in advance.

KD0RVY
Wayne

[WA4OTD]

Have you googled 2 meter amp or are you looking for 2m and 70cm? Fifty watts is pretty serious, you will need pretty good heat sink.

[KD0RVY]

Well I am looking for 2m/70cm since that's what my radio is. I have done A LOT of googling and still not getting a whole lot. Well if not 50w is 30w doable?

[K1ZJH]

A single band amp is doable, but the dual band requirements and the size are the deal breakers.

Pete

[N8WWM]

Back when I was building solid state amps I used this book extensively. One thing to bear in mind, Radio Shack marketed these puppies in a small page/text format that made the PC board layout too small. If you copy the page at 133 percent you get the correct size. Of course my memory may have failed me. If so, you just need to shoot a few copies of the part's size specification in the range of 129 to 134% and compare the drawing with an actual transistor.

Here's one for sale on Amazon...
http://www.amazon.com/gp/offer-listi...&redirect=true

I'd suggest looking up the Motorola MRF-245 as a starting point. You can drive it with 5 watts and get 40 or so out. The beauty of that is if you drive it with 10 watts you get 80 watts. Plus, at HT power the amp will stay a bit cooler. The complete amp is in this book, along with PC board layouts. They don't make the 245 anymore but the 247 is the same transistor with a bit better specs.

73 Doug

PS...if you want to learn about small VHF amps this is the book for you. I have had mine since 1978 and never grow tired of it or find the info stale.

[KB4QAA]

Regarding improving your HT performance...

-Adding a counterpoise will provide an noticeable improvement. Just add a wire about 19.5 inches long and connected to the antenna base. I recommend a very thin flexible wire so you can easily roll it up.

-Another way would be to make a simple two or three element Yagi or Quad antenna that could be handheld or mounted on a simple tripod or stand.

[AD6KA]

Since the title of this thread is "Building an HT Amp",
there are two kit offerings from Communications Concepts, Inc.
BUT they are 2m only. Biased Class AB for FM and SSB
(for that FT-817, hihi)
Full and partial kits available.

Model 335A 35w:
http://www.communication-concepts.com/new_page_19.htm

Model 875A 75w
http://www.communication-concepts.com/new_page_20.htm

I agree with those who say an HT as your first ham purchase
is a really bad idea. Some years ago I worked part time at HRO and
we saw quite a few newcomers do this and quickly lose interest.

Thing is, if you try to talk them into a mobile rig, with coax, antenna,
and power supply (or without PS) they sometimes think you are trying to
"Bait and Switch" them into sepnding more money.

[WA4OTD]

Have you seen this? http://www.qsl.net/wn2a/DualBand_PA.pdf

VHF/UHF amps are are pretty simple but demanding. I'm sure there are many more instructions/kits if you look.

I always see a lot of these bricks at hamfests for not very much if there is a hamfest near you coming up.

[KD0RVY]

Yeah I did come across that. Wasn't sure what to make of it to be honest. Looks kind of bulky too. I honestly thought while looking at it that maybe it was some kind of old school amp...lol

[WB2WIK]

So I currently have my Wouxun KG-UV6D and I would like to build an amp for it. I'm thinking something since the radio is 5w, I would want to do 5w in and then be able to get it up to 30w-50w or so. I have been doing a lot of looking and I am just not finding anything yet. I would like a kit that is very compact, maybe even Altoid tin size if possible, and would be easy to put together. Doe's anyone in here know of any great kits or where I could look to get such a kit? Thank you all in advance.

KD0RVY
Wayne

There aren't any I know of, at all. Mirage makes a preassembled 2m/70cm amp, this one: http://www.mirageamp.com/Product.php?productid=BD-35

It's cheap, it's small, but a whole lot larger than an Altoids tin. To run even 35W output power means you have to dissipate 35W of power in the amplifier, which must escape as heat. The Altoids tin would have to bolt to a heat sink four times larger than the tin to make that work.

This amp draws 7A at 13.8Vdc, so you need a power supply that is considerably larger than the Altoids tin to power it, anyway.

Best thing to do, usually, when "more power" is needed is just get a mobile rig and use that, instead of the hand-held. Overall better investment.