[AMRadio] dds information


Jim candela jcandela at prodigy.net
Sat Jul 17 12:46:51 EDT 2004




Jim,

	You got me excited and then I realized that the $50 price you mentioned may
have been a typo. If not where are these to be had for 50 bucks? There is a
PTS 040 on Ebay now "buy it now" for nearly 4 grand.... These would fit
nicely next to a boat anchor..

	I have two BC458's modified as per CE bulletins. It is true that I never
went through the long procedure to align them, and to temperature compensate
them. They have one major drawback, and that is the series dropping resistor
in the back heats things up pretty well, and the dang thing drifts as a
consequence in two stages. The parts near the 1626 heat up first, and later
the parts within the oscillator shielded enclosure start heating up.

	I once got on 7215 where there were some that would say they were running
hi-fi SSB (is that an oxy-moron?). Initially they were impressed with my
phasing QRO'd 20A setup. I was between the two stage drift, and remember on
40m, the BC-458 output is tripled. Then I drifted up 200 hz during an old
buzzard 60 second transmission as phase two of the drift started. I switched
to receive, and there were 20 people screaming at me for "drifting out of
the band"!

	I hope to have better luck with the DDS.... See link below for a PTS 040
for sale:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4683&item=2585135703&
rd=1&ssPageName=WD1V

Regards,
Jim

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net]On Behalf Of James M. Walker
Sent: Friday, July 16, 2004 10:52 PM
To: Discussion of AM Radio
Subject: Re: [AMRadio] dds information


Well Gang,
I have several PTS signal sources here, and they provide coverage over a
wide range of frequencies at adjustable output levels. I use one as  a
signal source for my RCA BTA-1M, that would be the PTS 040 model. As a
shop signal source I use the PTS 250 with the GPIB interface for
computer
control. They are stable and highly accurate over their frequency
ranges,
and no drifting. I know you will say, what a lab instrument, is going to
be expensive, but none of mine cost more than 50.00, they are still easy
to purchase from the Mfr, at their full price, but more and more they
are
showing up at bargain prices. Well worth the effort to look around for
them.

On the case for the BC-458 VFO used with the Central Electronics 10A-10B
and 20A series, I have two of the modified vfos per the CE manual, they
both work great and do not drift in NORMAL operation. The CE manual
gives
good directions for using them, and applied per the manual they BC-458
as
a "mixing" signal source is extremely stable signal source.

FWIW

Info on PTS can be found here http://www.programmedtest.com/
including spec and ratings and current pricing info.
Jim
WB2FCN
http://eshop1.chem.buffalo.edu


"KC8OPP Roger S." wrote:
>
> Neal,
>
> I use a Raytheon RA-250 on 160 and for the VFO I
> bought a master oscillator for an ARC-38 from the Fair
> Radio Store.  I think that it was around $35.  Inside
> this beast is a Collins PTO that tunes 1.75-3Mhz, I
> may be off a bit on the freq range.
>
> I built a regulated power supply and added a cathode
> follower circuit for the PTO and use it to feed the
> grid of the oscillator in the RA-250.  Works great,
> very stable and easy to use.
>
> Looked at your web site and saw the RCA, looks great.
> I am in the process of re-working a RCA BTA-1R for
> multi band operation.  You can have a look at it here,
>
> http://photos.yahoo.com/kc8opp
>
> I will be using a Kenwood 520 for an exciter for the
> RCA.  I have been using this same radio with a HB rig
> for the last year and seems to work good.
>
> Good luck with your projects.
>
> 73's
> Roger
> KC8OPP
>
> --- Neal Newman <groucho at skyweb.net> wrote:
> >  Jim Do you have a website up?
> > I run a few broadcast transmitters on 160 Meters
> > AM.... looking for a
> > crystal replacement to change Frequencys On 160
> > meters..  any plans on a
> > VFO for these type Rigs?
> > Neal Newman-KA2CAF
> > Big Iron  collector
> > http://www.angelfire.com/nj4/wttm/rca.html
>
>
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