pete ke90a wrote:
snip
If you brush the dust off the circuit boards, make sure that you don't
bump any of the trimmer capicators.

Pete KE9OA

Reminds me of when I was a kid - my best friend decided to soup up his
dad's radio and found the trimmer caps and the slugs in the IF
transformers were loose and needed tightening.

Any update on the enthusiast's MW radio you were working on?

Hi Mark,
All of the RF design is done...........I have built two
prototypes. On one of them, I use a ten turn pot to tune the VCO. The other
unit uses a PLL for tuning. I think we will have some time to develop the
tuning software, etc.
We were tied up with a big project for the last several months; this was the
Automark election machine that you may have heard about in the news. All
kinds of fun things, getting it through EMC certification.
Speaking of MW receivers, I did purchase the Boston Acoustics
Receptor clock radio. MW performance is not bad, but the selectivity is
pretty wide. It appears to be a single conversion affair that uses a 450kHz
I.F. It might be a double conversion unit, but when I peaked the Radio Shack
loop antenna on the image frequency, I was able to receive the image. It
could also be that the (2 X 2nd I.F.) rejection isn't too good, if this is
truly a double conversion unit. Is it worth the 150 dollars? Could be. I did
call up Boston Acoustics to see if I could get ahold of some service
information. The wouldn't make it available. When I asked them how to remove
the main circuit board from the unit so that I could change the 450kHz
filter, they explained that they couldn't give me that information, since I
if were electrocuted, they would be liable. When I explained that I was
going to quote them in my review, they said that it was ok. If anybody
figures out how to get this thing apart, feel free to contact me.
Oh, another thing............it could be off topic, but this is good for
you Drake '7 line folks. If you change the 1st mixer in your Drake R7/TR7 to
a Mini-Circuits SRA-3MH (Level 13) mixer, and you change the 1N4148s in the
2nd mixer to matched sets of 1N5711 hot carrier diodes, the receive
performance improves a bit. The original 1st mixer has an SSB conversion
loss of 6.5dB, while the Mini-Circuits mixer has a conversion loss of
4.75dB. As far as the 2nd mixer, it is good to get rid of those general
purpose switching diodes and replace them; the 1N5711 Hot Carrier diodes
have lower loss, better IM characteristics, and they are designed for RF
applications.
One thing about that Radio Shack cleaner. I have used some of it in the
past, and it has dissolved plastic switch wafers. I would stay away from
that. The Caig De-Oxit is in the same price range, and it doesn't destroy
components.
In the old days, we used to use Freon based solvents to clean circuit
boards. I would get ahold of the De-Oxit and play it safe. Caig is the same
company that marketed a product called Tweak.

Pete

"Mark S. Holden" wrote in message
...
pete ke90a wrote:
snip
If you brush the dust off the circuit boards, make sure that you don't
bump any of the trimmer capicators.

Pete KE9OA

Reminds me of when I was a kid - my best friend decided to soup up his
dad's radio and found the trimmer caps and the slugs in the IF
transformers were loose and needed tightening.

Any update on the enthusiast's MW radio you were working on?

Pete KE9OA wrote:

As far as the 2nd mixer, it is good to get rid of those general
purpose switching diodes and replace them; the 1N5711 Hot Carrier diodes
have lower loss, better IM characteristics, and they are designed for RF
applications.

Is the 1N5711 a good substitute for the 1SS135?

According to
http://www.geocities.co.jp/SiliconVa...v-di.htm#mixer
the 1SS135 appears to be a VHF/UHF switching diode, from Rohm
Semiconductors. It could be a good diode, but I know that the 5711 is
intended for mixer/detector service. I was unable to find a data sheet for
the 135, so I can't make direct comparisons. I have used the 5711 over the
past several years, with good results. Awhile back, I picked up a batch of
matched quad sets of these diodes from the Rockwell-Collins Inventory
Disposal store for around a dollar a pound. Too bad I got rid of most of
them.........................I thought I would be living out there for
longer than I did. Easy to take things for granted, when they are plentiful.
Fortunately, these things are currently available, and they aren't too
expensive.

Pete

"starman" wrote in message
...
Pete KE9OA wrote:

As far as the 2nd mixer, it is good to get rid of those general
purpose switching diodes and replace them; the 1N5711 Hot Carrier diodes
have lower loss, better IM characteristics, and they are designed for RF
applications.

Is the 1N5711 a good substitute for the 1SS135?

Thanks Pete. Anything new to report on the MW receiver?

Pete KE9OA wrote:

According to
http://www.geocities.co.jp/SiliconVa...v-di.htm#mixer
the 1SS135 appears to be a VHF/UHF switching diode, from Rohm
Semiconductors. It could be a good diode, but I know that the 5711 is
intended for mixer/detector service. I was unable to find a data sheet for
the 135, so I can't make direct comparisons. I have used the 5711 over the
past several years, with good results. Awhile back, I picked up a batch of
matched quad sets of these diodes from the Rockwell-Collins Inventory
Disposal store for around a dollar a pound. Too bad I got rid of most of
them.........................I thought I would be living out there for
longer than I did. Easy to take things for granted, when they are plentiful.
Fortunately, these things are currently available, and they aren't too
expensive.

Pete

"starman" wrote in message
...
Pete KE9OA wrote:

As far as the 2nd mixer, it is good to get rid of those general
purpose switching diodes and replace them; the 1N5711 Hot Carrier diodes
have lower loss, better IM characteristics, and they are designed for RF
applications.

Is the 1N5711 a good substitute for the 1SS135?

I wish there was.....................it seems that there is always a project
ahead of mine at work. They do want to market the radio, but the software
folks are tied up in more lucrative projects. A friend of mine offered to
write the 145170 PIC code for me last Christmas.............I should have
let him do it. Originally, I just wanted to market a barebones synthesized
radio, but the boss wanted to have a spectrum analyzer display, bass and
treble controls, electronic volume, memories, automatic tracking of the
loopstick antenna...........etc. At Motorola, we used to call this "creeping
elegance". The radio is done............all we need is the uP
(arrrggggggggghhhhhhhhhh) control section to be completed.
I built myself a home version of this unit that has no sync detection, no
synthesizer, and manual tuning of the loopstick. I tune the VCO with a
Spectrol 10-turn pot, and after the first 5 minutes with about a 10kHz
drift, it stays tuned all night.
Right now, the radio sits up on my shelf along with some of my other
homebrew radios.
If this thing ever gets to market, I think you will have quite a bit of fun
with it. When I get my website up again, I will post some pictures of the
prototypes up there.

Pete

"starman" wrote in message
...
Thanks Pete. Anything new to report on the MW receiver?

"Pete KE9OA" wrote in message
news
I wish there was.....................it seems that there is always a
project ahead of mine at work. They do want to market the radio, but the
software folks are tied up in more lucrative projects. A friend of mine
offered to write the 145170 PIC code for me last Christmas.............I
should have let him do it. Originally, I just wanted to market a barebones
synthesized radio, but the boss wanted to have a spectrum analyzer display,
bass and treble controls, electronic volume, memories, automatic tracking
of the loopstick antenna...........etc. At Motorola, we used to call this
"creeping elegance". The radio is done............all we need is the uP
(arrrggggggggghhhhhhhhhh) control section to be completed.
I built myself a home version of this unit that has no sync detection, no
synthesizer, and manual tuning of the loopstick. I tune the VCO with a
Spectrol 10-turn pot, and after the first 5 minutes with about a 10kHz
drift, it stays tuned all night.
Right now, the radio sits up on my shelf along with some of my other
homebrew radios.
If this thing ever gets to market, I think you will have quite a bit of
fun with it. When I get my website up again, I will post some pictures of
the prototypes up there.

Pete

"starman" wrote in message
...
Thanks Pete. Anything new to report on the MW receiver?




Hi Pete

What I should buy, Caig's Pro Gold or Deoxit 5? I want to clean pots,
switches, etc. They seem to be similar. Any particular cheap vendor you buy
from on the net? Don't know if they sell this stuff locally.

Thanks
Lucky

"Pete KE9OA" wrote:

At Motorola, we used to call this "creeping
elegance".

Oh, you worked for the Dark Side at Bat Wing Central, huh?

I've always called that "creeping featureism."

--
Eric F. Richards

"Nature abhors a vacuum tube." -- Myron Glass,
often attributed to J. R. Pierce, Bell Labs, c. 1940

Wayyyy back in the olden days,when Shortwave Radio was aborning.It
wasen't like they could step over to the nearest handy dandy radio store
and buy a factory made shortwave radio,, No Sir! They had to round up
some parts and or buy some kind of a kit thingy and build their own
Shortwave Radio.
cuhulin

Pete,

I hope you make it to production with the MW receiver. It sounds like a
real winner, especially if it gets all the bells and whistles. In the
meantime is there any chance for offering the sync' detector as an
outboard unit which could be added to a car radio? If not, are you free
to release the schematic for homebrew projects?

Thanks

Pete KE9OA wrote:

I wish there was.....................it seems that there is always a project
ahead of mine at work. They do want to market the radio, but the software
folks are tied up in more lucrative projects. A friend of mine offered to
write the 145170 PIC code for me last Christmas.............I should have
let him do it. Originally, I just wanted to market a barebones synthesized
radio, but the boss wanted to have a spectrum analyzer display, bass and
treble controls, electronic volume, memories, automatic tracking of the
loopstick antenna...........etc. At Motorola, we used to call this "creeping
elegance". The radio is done............all we need is the uP
(arrrggggggggghhhhhhhhhh) control section to be completed.
I built myself a home version of this unit that has no sync detection, no
synthesizer, and manual tuning of the loopstick. I tune the VCO with a
Spectrol 10-turn pot, and after the first 5 minutes with about a 10kHz
drift, it stays tuned all night.
Right now, the radio sits up on my shelf along with some of my other
homebrew radios.
If this thing ever gets to market, I think you will have quite a bit of fun
with it. When I get my website up again, I will post some pictures of the
prototypes up there.

Pete

"starman" wrote in message
...
Thanks Pete. Anything new to report on the MW receiver?


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