On Tue, 10 Feb 2009, Tim Wescott wrote:


If it's the latter -- well, the same place may have what you want, or you
may be out of luck (did the Heath rigs _have_ an AM selection? Mine
certainly didn't), or you may have to mix to some other frequency (i.e.
455kHz), filter, and mix back. Note that my SB-201 didn't have an AM
detector, either, so it may be more than just a filter that you need.

If they kept the same IF frequency, and I know the SB line did use
something in the 3MHz range, then there was at least one AM filter, for
the shortwave band version of the SB series receiver, the SB-313 or
something.

There was a Heathkit receiver/transmitter set for AM about the time
of their early SSB rigs, same sort of styling as the SSB rig of
the time. The era of the Indian names. I don't know whether those
used a high IF or used the traditional 455KHz, but if it was the
former, they'd surely use the same 3MHz range scheme as the SSB
equpment.

Michael

On Tue, 10 Feb 2009 11:39:29 -0500, Michael Black wrote:

On Tue, 10 Feb 2009, Tim Wescott wrote:


If it's the latter -- well, the same place may have what you want, or
you may be out of luck (did the Heath rigs _have_ an AM selection?
Mine certainly didn't), or you may have to mix to some other frequency
(i.e. 455kHz), filter, and mix back. Note that my SB-201 didn't have
an AM detector, either, so it may be more than just a filter that you
need.

If they kept the same IF frequency, and I know the SB line did use
something in the 3MHz range, then there was at least one AM filter, for
the shortwave band version of the SB series receiver, the SB-313 or
something.

There was a Heathkit receiver/transmitter set for AM about the time of
their early SSB rigs, same sort of styling as the SSB rig of the time.
The era of the Indian names. I don't know whether those used a high IF
or used the traditional 455KHz, but if it was the former, they'd surely
use the same 3MHz range scheme as the SSB equpment.

Michael

I believe there was a regular brand rig (Kenwood?) of about that era that
also used the same mixing scheme, and had the same frequency fixed IF, if
not all the same matching impedances. I can't really recall, though,
other than I was thumbing through a replacement filter catalog and
noticed it because I had the SB-201.

--
http://www.wescottdesign.com

Tim Wescott wrote:


I believe there was a regular brand rig (Kenwood?) of about that era that
also used the same mixing scheme, and had the same frequency fixed IF, if
not all the same matching impedances. I can't really recall, though,
other than I was thumbing through a replacement filter catalog and
noticed it because I had the SB-201.

My fuzzy recollection says that 3395 shouldn't be difficult to find. A
check of completed auctions on ebay didn't bear that out. I suppose it
depends on how big of a hurry you're in

-Bill

On Tue, 10 Feb 2009, Tim Wescott wrote:

I believe there was a regular brand rig (Kenwood?) of about that era that
also used the same mixing scheme, and had the same frequency fixed IF, if
not all the same matching impedances. I can't really recall, though,
other than I was thumbing through a replacement filter catalog and
noticed it because I had the SB-201.

That sounds familiar, though I can't remember which brand it was either.

I just did some searching, and I was thrown off by the mention of "early"
in the first post.

I was thinking of the Heathkit Commanche as a small receiver suitable
for mobile operation, and it was used in tandem with the am Cheyenne
transmitter. A check shows that receiver used a 3MHz IF. The Mohawk,
which was a full blown receiver, used 1682KHz and then down to 50KHz,
obviously not a standard combination in Heathkit receivers. The HR-20
Mobile SSB receiver used a 3MHz IF too. A quick search doesn't turn
up what IF's the matching SSB transmitters were using, but I assume
they too were 3MHz.

So then Heathkit moved to 3395KHz, and that was pretty standard for
a really long time. I think even the HW series of monoband SSB
transceivers used the same frequency, though they used multiple
crystals rather than prebuilt crystal filter.

It's all relative, but I think of "early" as the pre-SB line, not
the SB line itself. Heath kept the SB line going into the seventies,
with cosmetic changes but the same basic design.

Michael VE2BVW