From rec.radio.amateur.homebrew 779
Path: ucbvax!agate!howland.reston.ans.net!usenet.ins.cwru.edu!news.ecn.bgu.edu!willis1.cis.uab.edu!spam.dom.uab.edu!user
From: gila005@uabdpo.dpo.uab.edu (Stephen Holland)
Newsgroups: rec.radio.amateur.homebrew
Subject: Re: Low-cost VHF amplifier application note
Message-ID: <gila005-161193124904@spam.dom.uab.edu>
Date: 16 Nov 93 17:44:51 GMT
References: <holland-151193111058@beagley.dom.uab.edu>
Sender: root@cis.uab.edu (Operator)
Followup-To: rec.radio.amateur.homebrew
Organization: Univ. of Alabama at Birmingham
Lines: 32
In article <holland-151193111058@beagley.dom.uab.edu>,
holland@gasmac.dom.uab.edu (Steve Holland) wrote:
>
> One person asked about what application note had a reference to
> a vhF power amplifier. I got several frol motorola. One, a
> broadband 300 watt amplifier from 10 to 300 MHz was interesting
> until I saw the power transistor alone cost about $300 in quantity
> of one. A much more affordible amplifier was described in
> engineering Bulletin EB-90, Low-cost VHF amplifier has broadband
> performance. It uses the MRF 260 and MRF 262 and includes the
> PCB pattern in the note. 15 Watts output at 146 MHz.
>
> Darn, I realize I had another note for a higher note for a higher
> power amplifier which included an automatic T/R relay in the
> design. I'll post on that when I bring it into work.
The other note of interest is AN-791m a 75W and 35W power amp optimized
for 144-148 MHz. It has a built in carrier operated relay, which stays
up in SSB and CW with a built in delay on releasing the relay.
To the person who emailed me, the responses bounced.
There are kits for these amps from communication concepts,
508 Millstone Drive
Beaver Creek OH 45434-5840
513-426-8600
The 35 watt and 75 watt amps are $80 and $120 respectivley.
Does anyone have experience dealing with them?
Steve Holland
From rec.radio.amateur.homebrew 782
Path: ucbvax!agate!howland.reston.ans.net!spool.mu.edu!news.clark.edu!netnews.nwnet.net!news.uoregon.edu!newsadmin
From: jeffh@ludwig.cc.uoregon.edu (Jeff Hite)
Newsgroups: rec.radio.amateur.homebrew
Subject: Re: Low-cost VHF amplifier application note
Message-ID: <2cb6ta$mj7@pith.uoregon.edu>
Date: 16 Nov 93 18:41:46 GMT
References: <gila005-161193124904@spam.dom.uab.edu>
Organization: University of Oregon
Lines: 43
NNTP-Posting-Host: ludwig.cc.uoregon.edu
In article <gila005-161193124904@spam.dom.uab.edu> gila005@uabdpo.dpo.uab.edu
(Stephen Holland) writes:
> In article <holland-151193111058@beagley.dom.uab.edu>,
> holland@gasmac.dom.uab.edu (Steve Holland) wrote:
> >
> > One person asked about what application note had a reference to
> > a vhF power amplifier. I got several frol motorola. One, a
> > broadband 300 watt amplifier from 10 to 300 MHz was interesting
> > until I saw the power transistor alone cost about $300 in quantity
> > of one. A much more affordible amplifier was described in
> > engineering Bulletin EB-90, Low-cost VHF amplifier has broadband
> > performance. It uses the MRF 260 and MRF 262 and includes the
> > PCB pattern in the note. 15 Watts output at 146 MHz.
> >
> > Darn, I realize I had another note for a higher note for a higher
> > power amplifier which included an automatic T/R relay in the
> > design. I'll post on that when I bring it into work.
>
> The other note of interest is AN-791m a 75W and 35W power amp optimized
> for 144-148 MHz. It has a built in carrier operated relay, which stays
> up in SSB and CW with a built in delay on releasing the relay.
>
> To the person who emailed me, the responses bounced.
>
> There are kits for these amps from communication concepts,
> 508 Millstone Drive
> Beaver Creek OH 45434-5840
> 513-426-8600
>
> The 35 watt and 75 watt amps are $80 and $120 respectivley.
>
> Does anyone have experience dealing with them?
>
> Steve Holland
I assembled the 35W version about 6 yrs ago...used it for about 3 and sold it
at a hamfest. Worked fine for me and was fairly easy to put together, would
have been nice to have a pre-amp though.
--
Jeff Hite KF7SZ
Computing Center
U of Oregon
jeffh@ludwig.cc.uoregon.edu
From rec.radio.amateur.homebrew 784
Path: ucbvax!dog.ee.lbl.gov!agate!howland.reston.ans.net!cs.utexas.edu!uunet!world!dts
From: dts@world.std.com (Daniel T Senie)
Newsgroups: rec.radio.amateur.homebrew
Subject: Re: Low-cost VHF amplifier application note
Message-ID: <CGLwEq.LI6@world.std.com>
Date: 16 Nov 93 22:42:25 GMT
References: <holland-151193111058@beagley.dom.uab.edu> <gila005-161193124904@spam.dom.uab.edu>
Organization: Daniel Senie Consulting, Clinton, MA
Lines: 65
In article <gila005-161193124904@spam.dom.uab.edu> gila005@uabdpo.dpo.uab.edu (Stephen Holland) writes:
>In article <holland-151193111058@beagley.dom.uab.edu>,
>holland@gasmac.dom.uab.edu (Steve Holland) wrote:
>>
>> One person asked about what application note had a reference to
>> a vhF power amplifier. I got several frol motorola. One, a
>> broadband 300 watt amplifier from 10 to 300 MHz was interesting
>> until I saw the power transistor alone cost about $300 in quantity
>> of one. A much more affordible amplifier was described in
>> engineering Bulletin EB-90, Low-cost VHF amplifier has broadband
>> performance. It uses the MRF 260 and MRF 262 and includes the
>> PCB pattern in the note. 15 Watts output at 146 MHz.
>>
>> Darn, I realize I had another note for a higher note for a higher
>> power amplifier which included an automatic T/R relay in the
>> design. I'll post on that when I bring it into work.
>
>The other note of interest is AN-791m a 75W and 35W power amp optimized
>for 144-148 MHz. It has a built in carrier operated relay, which stays
>up in SSB and CW with a built in delay on releasing the relay.
>
>To the person who emailed me, the responses bounced.
>
>There are kits for these amps from communication concepts,
>508 Millstone Drive
>Beaver Creek OH 45434-5840
>513-426-8600
>
>The 35 watt and 75 watt amps are $80 and $120 respectivley.
>
>Does anyone have experience dealing with them?
>
>Steve Holland
I have built one of each size. The 75 watt one has been on a repeater
for quite some time now (over a year). I had to rebuild it a while
back because the RF sensing circuit was chattering the relay. I do not
know why, but the amplifier was going into oscillation. For the repeater
case, I just added a jumper so that when power is present, the relay is
pulled down, putting the amp into line. The only reason I did not
eliminate the relay altogether is that we want the amp out of line when
the AC power fails. For repeater use, I added a fan on the heatsink.
I loaned out the 35 watt model and a power supply to a new ham who had
been in one of my ham radio classes (I do LOTS of elmering!) and it worked
fine for a few days, then it developed the same problem with oscillation.
Fixing this one is harder, since I really DO want the RF sense switch
to work. I tried rebiasing the thing to class C, but there is still a
problem with oscillation after the first time RF is applied. This one
is going to wind up in the hands of the master (WA1RHP, an expert at
solid state amplifiers), to see if he can get it to work.
The old adage is true: you try to build an amplifier and you get an
oscillator. Try to build an oscillator and you get an amplifier!
If you are looking for a finished product, look at TE systems or
RF Concepts. (Stay away from Mirage).
--
---------------------------------------------------------------
Daniel Senie Internet: dts@world.std.com
Daniel Senie Consulting n1jeb@world.std.com
508-365-5352 Compuserve: 74176,1347
From rec.radio.amateur.homebrew 824
Path: ucbvax!agate!howland.reston.ans.net!europa.eng.gtefsd.com!emory!kd4nc!ke4zv!gary
From: gary@ke4zv.atl.ga.us (Gary Coffman)
Newsgroups: rec.radio.amateur.homebrew
Subject: Re: 2M 10w amp?
Message-ID: <1993Nov27.150335.17476@ke4zv.atl.ga.us>
Date: 27 Nov 93 15:03:35 GMT
References: <CH1q8E.BCu@mentor.cc.purdue.edu>
Reply-To: gary@ke4zv.atl.ga.us (Gary Coffman)
Organization: Destructive Testing Systems
Lines: 30
In article <CH1q8E.BCu@mentor.cc.purdue.edu> blumb@sage.cc.purdue.edu (Bill Blum) writes:
>Well, I have a choice.
>
>I can either shell out the $$ to buy a 2m amp for my HT, or I can buy a
>theory book, learn theory, and build one.
>
>Recommendations either way?
Buy the book! _Solid State Design for the Radio Amateur_ is growing
whiskers, but is still a good starting point. A somewhat more advanced
treatment is Chris Bowick's _RF Circuit Design_. Others will have their
favorite references to recomend. I'd suggest starting with a simple
2E26 amp like the PA in figure 17-24 of the 1962 Handbook. Tube designs
are simple and forgiving, and they glow pleasantly in the dark. :-)
Somebody suggested the Ramsey PA kit. You won't learn much circuit
theory from building it, but you'll learn a *lot* about taming spurious
outputs when you attempt to tune it. You might want it anyway as a
convienent source of metalwork and hardware that you can use to build
a decent amp. Or, you can pull a no-brainer and use one of the many
power brick ICs that are available. They're great, but you won't learn
much interfacing power to a 50 ohm in and out, unconditionally stable,
amplifier IC.
Gary
--
Gary Coffman KE4ZV | Where my job's going, | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems | I don't know. It might | uunet!rsiatl!ke4zv!gary
534 Shannon Way | wind up in Mexico. | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244 | -NAFTA Blues |