EMRFD Message Archive 931

Message Date From Subject
931 2007-08-05 14:10:11 Ted Bruce KX4OM Transceivers you have built
Hi, Allison,
From your participation in various groups that I follow, I know you
are a very experienced designer. Your comment on the number of rigs
you have built caught my attention, and I wonder if you have published
these designs. It's not widely known yet, except for some
announcements withing QRP ARCI, but I am the new editor of QRP
Quarterly, replacing Mike Boatright, KO4WX...well, actually replacing
VP Ken Evans, W4DU who was on the hook for the upcoming Fall issue
until last week, when he and Dick Pascoe convinced me I should take
the job.

I invite you to submit an article on one of your designs. If you are
interested, we can discuss it further, if you wish.

933 2007-08-05 19:57:52 Allison Parent Re: Transceivers you have built
940 2007-08-06 18:25:25 Ted Bruce KX4OM Re: Transceivers you have built
Well, I assumed that "Send email" meant an offline reply; obviously
not. That message wasn't intended for the group.

FB on your junk box. I have exactly one 40673, and one CA3028A. I
just made a little board in Eagle CAD using a CA3086 and it's
differential amp internal connections, another transistor in the chip,
and added resistors from the CA3028A data sheet. It will be
interesting to see how that works out. The 40673 should be so easy,
but 'fraid not.

Until I happened upon a 9MHz crystal filter, I was going to use 9.216
as an IF, for this current work in progress, since I got 20 of them at
about $.40 apiece (those are series ECS HC-49U), as are all of my
various HFO crystals. I did characterize a bunch of 9.0 HC-49US
crystals that I got from Jameco a couple of years ago, but the Rs is
much higher than any I've done, so I won't be using those.

I also collected a full set of Heathkit essentials, including the SSB
and CW filters, the LSB & USB BFO crystals, along with the HFO
crystals. I intend to put together something useful to me, but hardly
reproducible, so I understand what you say. The scarcity of 6146A
tubes has me miffed. I have an HW-101 that will not neutralize with
GE 6146B or 6146W tube, so I'm going to do something really unorthodox
and convert the PA to 2E26 finals. Those are available new at $6.95
from Pacific TV, plus I have a few good pulls from old Johnson Marine
VHF rigs. I plan on running it at QRP levels with the plate voltage
as low as I can bring it toward 400 V and still be ina good place on
the tube curves. Of course, I'll have to change the Pi-net coil,
because even at 600V, the values I worked out from the 1968 Handbook
show the Q moving from 10 to 20 for the existing Xl. At even lower Ep
& Ip, it would only get worse.

Yes, it will heat up the room for 5 Watts CW/10 Watts SSB, but the
first FM rig I had was a vibrator-supply rig run from a homebrewed
transformer, and it drew 15 amps on receive. The old-tech stuff is
interesting to fool with.

Good luck with your projects,


--- In emrfd@yahoogroups.com, "Allis
941 2007-08-06 21:29:05 Allison Parent Re: Transceivers you have built
945 2007-08-07 17:44:07 Ted Bruce KX4OM Re: Transceivers you have built
Comments in-line:

947 2007-08-07 21:13:12 Allison Parent Re: Transceivers you have built
949 2007-08-08 12:03:56 Ted Bruce KX4OM Re: Transceivers you have built
--- In emrfd@yahoogroups.com, "Allis
950 2007-08-10 16:26:19 sp9mrn Re: Transceivers you have built
> I recently bought 50 27.0 MHz HC-49Us on eBay for $3, taking that
> chance that they might be overtones. Alas, they aren't.

As I did :-). Nothing from my dream about roofing...

951 2007-08-11 05:02:47 w4zcb77 Re: Transceivers you have built
952 2007-08-11 05:12:56 w4zcb77 Filters
Nothing from my dream about roofing...
> >
> > MAc
> GM Mac. I read this as you looking to making a filter and so made a
> change to the subject line, but if you're looking towards making a ~
> 9 MHz filter, what bandwidth do you wish to end up with? I have
> several 8.8 MHz 8 pole 2.4 KHz lattice filters excess to my needs
> and looking for a good home.

Well, I THOUGHT I changed the subject line!
> Regards
> >
953 2007-08-11 17:08:01 sp9mrn Re: Filters
954 2007-08-11 18:08:32 Allison Parent Re: Filters