EMRFD Message Archive 3854
Message Date From Subject 3854 2009-12-12 12:13:34 tetranz Replacement for 2SC5739 ?
I wonder if anyone can recommend a replacement for the 2SC5739. Unfortunately, it seems to be discontinued part.
I built a W7ZOI Universal QRP TX for 80m. It works very well or at least it did until I started experimenting and, umm ... let the magic smoke out of a couple of 2SC5739s. Exactly why it happened, twice, may be the subject of another post but it's taught me that my next step has to be to build or otherwise acquire some simple test equipment to better understand what I'm doing.
I still have a couple of spares and I think some of the small kit vendors still have some but when that's gone it looks like it's the end of the road for the 2SC5739 which is a pity. I'd prefer to be working with something that is still current.
I see on Wes' site he talks about the MJE181 and 2SC5739 both as possible replacements for a previously discontinued transistor. It looks like the MJE181G from OnSemi is still in production and readily available from Mouser at about $10 for 25. Would it be a good choice? I'm trying to compare the datasheets but I don't quite understand all the relevant parameters yet. I'm mostly interested in 80 meters for now and happy if I can get 3 or 4 watts output.
73
Ross KB1KGA3856 2009-12-12 14:19:36 KB9BVN Re: Replacement for 2SC5739 ?
W8DIZ has the 2SC5739 in stock at $2 each. I think he said he had about 1000 of them, but could not get any more.
http://www.kitsandparts.com
73
----- Original Message -----
3858 2009-12-12 23:05:25 WA0ITP Re: Replacement for 2SC5739 ?
-------------------------------------------------------------------
Back to the bench, Winter's too valuable to waste!
I love this radio stuff !
72, 73 Terry, WAØITP
www.wa0itp.com
www.4sqrp.com
www.qrpspots.com
----- Original Message -----
3861 2009-12-13 12:06:15 w7zoi Re: Replacement for 2SC5739 ?
I thought that I had found a real gem with that 2SC5739. It is a great little part and will generate all kinds of RF power with ease. But alas, Panasonic tells us that is on the way out.
As you mentioned, we have the MJE181. I was able to get it to fly on 40 and I'm sure that 80 would also work. However, it is NOT a hot part at all. Gain is low, so you have to work at it a little more, but that's the fun, I guess. There are some other common bipolar power parts that work well at the lower bands, like the BD139. I grabbed some of them on a recent order, but have not yet fired one up. I recall a much earlier post3862 2009-12-13 12:24:32 k5nwa Re: Replacement for 2SC5739 ?
>Try these two;
>
>Hi Ross and group,
>
>I thought that I had found a real gem with that 2SC5739. It is a
>great little part and will generate all kinds of RF power with ease.
>But alas, Panasonic tells us that is on the way out.
>
>As you mentioned, we have the MJE181. I was able to get it to fly on
>40 and I'm sure that 80 would also work. However, it is NOT a hot
>part at all. Gain is low, so you have to work at it a little more,
>but that's the fun, I guess. There are some other common bipolar
>power parts that work well at the lower bands, like the BD139. I
>grabbed some of them on a recent order, but have not yet fired one
>up. I recall a much earlier post on this site about them.
>
>Study of the catalogs shows us some strong trends. I think that
>bipolar power is slowly becoming something of the past. The 2sc5739
>was a holdover for switching applications, but everything seems to
>be moving toward FETs of one kind or another for this chore. The
>MOSFETs are very abundant and amazingly cheap. Our challenge is
>going to be to find the ones that will also do the job we want with
>RF power amplifiers at the HF bands. It may be well to move beyond the IRF510.
>
>There are some great special RF FETs available that are in the $5
>category instead of the $1 area of the switching FETs. The one that
>seems to be emerging as a "standard" is the RD16HHF1. But there are others.
>
>Our goal with EMRFD was not to present circuits for duplication, but
>to provide some tools. Hopefully, we can find some good parts to use
>with our tools.
>
>So, I think that the longer term answer is to "Think FETs."
>
>73, Wes
>w7zoi
>
< http://www.dspradio.org/KSC1173Y > a very linear device
< http://www.dspradio.org/KSC2690A > very high voltage rating and 20W rating
Both are pretty cheap.
Cecil
k5nwa
www.softrockradio.org www.qrpradio.com
< http://parts.softrockradio.org/ >
Never take life seriously. Nobody gets out alive anyway.3865 2009-12-13 19:52:59 Mike Czuhajewski Re: Replacement for 2SC5739 ?
> and 20W rating
the price on that web site. Mouser has it with several different
suffixes, all of them 38 cents in small quantities.3866 2009-12-13 20:28:33 k5nwa Re: Replacement for 2SC5739 ?
>Mouser will hit you with $7 to $8 shipping for 1 transistor, I don't
>
> > <
> <http://www.dspradio.org/KSC2690A>http://www.dspradio.org/KSC2690A >
> very high voltage rating
> > and 20W rating
>
>You can also find this one at Mouser for substantially less than
>the price on that web site. Mouser has it with several different
>suffixes, all of them 38 cents in small quantities.
and I give discount with small quantities, and if you look at the top
of the page all semiconductors are about to get their prices lowered.
But aside from all of that I mentioned it because it works rather
well at HF all the way to 10M and beyond.
Cecil
k5nwa
www.softrockradio.org www.qrpradio.com
< http://parts.softrockradio.org/ >
Never take life seriously. Nobody gets out alive anyway.3867 2009-12-13 21:29:23 Mike Czuhajewski Re: Replacement for 2SC5739 ?
had, I wouldn't have said a thing :-)
To everyone else: Please look into my little flashy thing. ["Men
in Black" movie reference; a device for selectively erasing
people's memory. Or if you're someone that the Jedi mind tricks
work on, I'll wave my arm and say "You never saw my post!"]3868 2009-12-14 03:20:33 jim_kr1s Re: Replacement for 2SC5739 ? 3869 2009-12-14 05:05:34 Jim Miller Re: Replacement for 2SC5739 ?
That FET looks very interesting. How in the world do you figure out
the "trends" in the discrete semi world without attending a bunch of
conferences, tearing apart a lot of modern HF power gear or sharing a
lot of microbrews with a bunch of HF power designers?
73
jim ab3cv3870 2009-12-14 05:35:32 Francis DUPONT Re: Replacement for 2SC5739 ?
> Diz at Kits and Parts still has some http://kitsandparts.com/parts.phpHi Terry,
Many thanks for the info.
By the way, I have some difficulties to send you direct mails.
Always get:
> Undelivered Mail Returned to Senderand
> The mail system550 Blocked
>
>: host gateway.mchsi.com[204.127.203.150] said:
> 550-80.12.242.111 blocked by ldap:ou=rblmx,dc=mso,dc=att,dc=net
> for abuse. Please contact the administrator of your ISP or sendingAbusing, amusing...
> mailservice. (in reply to MAIL FROM command)
Have you got the LMF100?
73 Francis3871 2009-12-14 06:03:57 Mike Czuhajewski Re: Replacement for 2SC5739 ?
>
> "Your search returned results from our extended database of
> parts not
> presently available online. Please call us for ordering
> information."
> <http://www.mouser.com/contact/>
misinterpreted my comment. I was not talking about that, but
rather the KSC2690A which K5NWA mentioned. As of midnight, Mouser
had a few thousand of them listed online.3872 2009-12-14 06:30:27 Ross Re: Replacement for 2SC5739 ?
added a few BD139, KSC2690A and KSC1173Y to play with. I was aware that Diz
has some 2SC5739 but I prefer to use something that I can blow up without
feeling guilty that I'm destroying the world's dwindling supply.
The comments noted about FETs Wes. It looks like that's the way I should
really be going.
Cheers
Ross
[Non-text portions of this message have been removed]3873 2009-12-14 06:31:34 Pat Bunn Re: Replacement for 2SC5739 ?
Pat
N4LTA
----- Original Message -----
3875 2009-12-14 08:00:40 KK7B Regarding "Trends in Discrete Semiconductors"
Good question, but you got it backwards. The young (and not so young) guys designing discrete semiconductors, RFICs and RF power amplifiers--and presenting their work at professional technical conferences--go out of their way to share a microbrew with Wes. We are indeed fortunate that a gentleman of his stature in the professional RF world shares our passion for experimenting with amateur radio circuitry.
His work is often deceptively simple, but it is both brilliant and profound, and he presents it with comm3876 2009-12-14 09:05:30 Jim Miller Re: Regarding "Trends in Discrete Semiconductors"
Thanks for the insight! Like most (I suspect) I continue to find new
nuggets everytime I read EMRFD.
73
jim ab3cv