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Rag Chew => Off Topic Discussions => Topic started by: onanparts on February 08, 2013, 02:28:10 AM

Title: Rfconcepts VHF amps under the covers
Post by: onanparts on February 08, 2013, 02:28:10 AM
First up is an RFC2-417. 143-149Mhz 45 watts in 170 watts out brick. I've had this amp for about 15 years and it has been rock solid with no problems.



Title: Re: Rfconcepts VHF amps under the covers
Post by: onanparts on February 08, 2013, 02:31:47 AM
Next up an Rfconcepts VHF/UHF mini brick.
Title: Re: Rfconcepts VHF amps under the covers
Post by: boB on February 08, 2013, 03:09:29 AM
Thanks for the pix, TJ !

I love RF circuitry.  I haven't done a lot of RF amp building but would really like to do more.

I usually work on trying to reduce RF radiation !

boB
Title: Re: Rfconcepts VHF amps under the covers
Post by: onanparts on February 08, 2013, 04:23:13 AM
Quote from: boB on February 08, 2013, 03:09:29 AM
Thanks for the pix, TJ !

I love RF circuitry.  I haven't done a lot of RF amp building but would really like to do more.

I usually work on trying to reduce RF radiation !

boB

Hi boB,

I didn't take any pics but have another Rfconcepts brick like the first one but it has a driver pill so 10 in 170 out. Great for the HT in the mobile. 300MW drive =20 watts out. 5 watt drive gets me 150+ out. Circuit designs are works of art to me. Little cities full of diodes, transistors, resistors, IC's etc.  ;D

Are you and the usual suspects going to be at the Mike and Key hamfest next moth? I think I'm going to be at the same table as last year.
Title: Re: Rfconcepts VHF amps under the covers
Post by: niel on February 08, 2013, 12:39:23 PM
nice stuff. i don't think that fm has much of a need for that high of power unless you're on simplex. ssb is great on vhf/uhf and the power does come in handy there. only real problem going ssb is most use horizontal polarity making the easier high gain verticals to be a 20db handicap for ssb right out of the gate. i have a kenwood ts2000 and would really love a good multiband omnidirectional horizontally polarized antenna for my limited mounting abilities on this city type property. i'm not asking for too much now am i? (sarcasm)
Title: Re: Rfconcepts VHF amps under the covers
Post by: boB on February 08, 2013, 06:21:52 PM
Quote from: onanparts on February 08, 2013, 04:23:13 AM

Are you and the usual suspects going to be at the Mike and Key hamfest next moth? I think I'm going to be at the same table as last year.


I'll be there but don't know if we will have a table or not.

Agree on RF stuff being kind of a work of art.

Sort of looks like plumbing some times.

boB
Title: Re: Rfconcepts VHF amps under the covers
Post by: onanparts on February 09, 2013, 01:00:00 AM
Quote from: boB on February 08, 2013, 06:21:52 PM
Quote from: onanparts on February 08, 2013, 04:23:13 AM

Are you and the usual suspects going to be at the Mike and Key hamfest next moth? I think I'm going to be at the same table as last year.


I'll be there but don't know if we will have a table or not.

Agree on RF stuff being kind of a work of art.

Sort of looks like plumbing some times.

boB

You're welcome to camp out at our table if your friends don't have one. I'll let you know the table number. I have it someplace as I just received the postcard confirming the spot.

More pics?

Yes!

This is the stack. Two pill high drive on top and 3 pill low drive bottom. And a look inside the 3 pill brick.



Title: Re: Rfconcepts VHF amps under the covers
Post by: onanparts on February 09, 2013, 01:04:12 AM
A little closer....
Title: Re: Rfconcepts VHF amps under the covers
Post by: onanparts on February 09, 2013, 01:05:23 AM
One more..... :)
Title: Re: Rfconcepts VHF amps under the covers
Post by: dbcollen on February 09, 2013, 01:15:38 AM
looks very primative compared to the modern SMD boards
Title: Re: Rfconcepts VHF amps under the covers
Post by: onanparts on February 09, 2013, 02:35:14 AM
Quote from: dbcollen on February 09, 2013, 01:15:38 AM
looks very primative compared to the modern SMD boards

One of the many reasons I like old junk. These amps were made roughly 20 years ago. You can actually SEE the components and easily make repairs, if required, without a magnifying glass! Plus, they were made to last a long time. Mine are still working just fine with no repairs and most likely will be around for another 20 years.  ;D

Niel,

These are my spring VHF/UHF antenna projects. The VHF beam has been in storage the last 10 years. It took a fall from the tower during a big blow. Survived in good shape just need to straighten out a few elements.

It's a Cushcraft A144-11 designed for 144-146Mhz. 13.2 dBd forward gain. 20 dB front to back ratio. Rated for 1KW PEP. Design has been around a LONG time. Late 50's or so. The beam is not really optimized for gain but hey, I paid $10.00 for it so no complaints here.  :) SSB on the flat side and driving the RFC with my 706 it hit around 200 watts to the dummy load so I'll be trying for some DX contacts when the bands are active, or even when they are not.

The UHF beam was $1.00 at a hamfest last year. Have not played with it yet but will get to it as time permits.