It's MICRO1700/DOG RADIO/1020 CC/SLUG 88.3, Etc.
I miss you of you guys very much. It has really been
impossible to get on the board here. Everything here is really
upside down.
I just wanted to ask a quick question. So you guys can't
see anything wrong with getting the 1.0 version board
over on E-Bay for that low price - legally, I mean. I would
be using it within Part 15.239.
As far as I can tell it's OK.
Again I miss you all. And thank you so much for
the nice E-mails, especially around the New Year.
It means a lot.
Very very best wishes to you all.
Bruce, GNAT 90.9, CC 1020, DRS2, etc., etc., etc.
Very good to hear from Bruce MICRO1700 following a lengthy radio silence.
My introduction to the Wholehouse FM was with Version 2.0, I never knew anything about Version 1.
Therefore, anything that gets reported here about Version 1 will be interesting to hear about.
Probably the two main things to document are the field strength results on the frequency of operation, and the harmonic and spurious radiation characteristics.
Beyond those main concerns, added questions would be...
Can V1 be operated as a mono transmitter?
Does it have a unique connector/antenna?
I actually had a version 1.0 Whole House transmitter.
It broke, but it wasn't the fault of the transmitter. It
was an accident where many things fell off of a table,
and the transmitter sort of got squashed.
Out of the 7 channels on the top of the FM BCB, I used
107.5 for a whole different station (Pigs Playing Tennis Radio).
NO - -- actually it was just for an in house link. No pigs playing
tennis.
The original transmitter just had a wire for the antenna. I don't
remember the length, but I didn't try to change anything. The
wire just came out of the enclosure - there was no connector.
As far as I remember, the transmitter sounded OK in stereo. It
was not made to switch over to mono. Although I never checked
for spurious radiation outside of the FM band, the main signal
was within 15.239, so I wasn't worried about interference from
the transmitter to other radio services. (Maybe I should have been.)
If I got one of these boards, it would be just to get while they are
available. My other FM transmitters are getting old, so this would
just be another backup. (Probably for an in house link.)
I'm sorry I haven't been on the board. There have been many things
going on, and life has been like jumping though lots of little hoops.
And I think the shoes I'm wearing are way too big, and the left shoe
is on the right foot, and the right shoe is on the left one.
I hope within a year, everything will be straightened out as best
as it can be. Then, hopefully, with some luck, it will have a Part
15 station again.
Very very best wishes, Carl, it is nice to talk to you!
Sincerely,
Bruce, The Micro/Dog/Whatever Name I Can Think Of
Next Stations.
I see there were some posts on here about the little FM transmitter being sold as surplus which is/was the original (gold?) Whole House transmitter. It’s a nice little package and the thing I like about it is its “through hole” construction which makes it easy to modify. The BH 1417 is SMD though.
Some time ago I bought one of the part 15 FM transmitters from a search of “part 15 transmitter” on eBay. I enjoy working on these types of things, and have many FM and AM transmitters. I use them mainly for broadcasting around the house and in the yard.
I modified and mounted the small Whole House transmitters in a nice metal enclosure. I wanted to use a smaller metal box but I decided to use the one I did as it was available from the local Radio Shack Store.
Refer to the schematic link at the bottom of this post. The schematic is also I on the eBay site selling the “part 15 radio transmitter”
The modifications:
R17 - R7 changed to 24K
R 16 - R18 changed to 68K
These are in the audio input circuit
This allows more audio signal to reach the BH 1417 if desired if the input signal is lower than what would be considered normal.
Other modifications are:
R2 changed to 4.7 K
R3 changed to 5.6K
I made these changes as the modulation depth was improved, although the original resistors did a good job also.
On the audio inputs I used ferrite EMI/RFI filters to choke out any interference which may come through the audio lines. I also used this filter on the B+ input to the transmitter so no RF would find its way into the transmitter from the power supply.
I added a five volt regulator so I can run the transmitter from various supply voltages.
I changed C3 and C4 to 3.3 nano farads. This changes the time constant for the pre emphasis to the USA standard of 75 micro seconds, (the default was 50 micro seconds) and this change really made a nice difference in the top end of the frequency response. The transmitter sounds nice and crisp now, along with very nice bass and everything in between!
If you look at the picture of the transmitter you will see I removed the power switch on the board, I didn’t need it because I am using a power switch on the aluminum case. I installed an additional LED pilot light, 100K twin pot audio taper volume control, RCA input jacks, banana power jacks on the back and RF connection.
The BH1417 chip is made to operate at the high end of the band (106.7-107.9) and also at the low end (88.7 to 88.9) however as the circuit board is configured; the transmitter will only operate on the high end of the band
The circuit board as configured has Vcc going to pin 8, 12 and pin 18. Pin 8 and 12 are normal connections, however Vcc going to pin 18 will lock the chip into the high end of the band.
In order to get to the lower frequencies, Pin 18 must be” low” or grounded or appear grounded through a resistor. Unfortunately, it appears the Vcc to pin 18 is on a trace which is under the chip and I could not get to it to disconnect the positive voltage to pin 18.
I have a few of these boards and the next look at one I will “ lift” the pin 18 of the chip off the board and run a 100 k resistor to ground from that pin. Doing that the chip should operate in the lower region and give the lower frequencies.
The three existing switches then should select the lower frequencies of the FM band 87.7 87.9 88.1 88.3 88.5 88.7 88.9
In the past using the BH 1417 chip, I had to use a small piece of powdered iron core or a chip of ferrite to increase the inductance of the oscillator coil to get the transmitter to work in the 88 MHZ region. I have not tried making this board work in the lower region as of yet, so it may work properly without any modifications to the inductance of the oscillator coil.
I had made some earlier modifications to get the transmitter to operate at the lower end of the band but didn’t finish the pursuit, I wanted to finish the project and the upper frequencies this time is fine for my applications.
The only thing I noticed about the schematic the diagram shows from pin 18, a connection to the switches , and then the same line continues on to one end of C19 and then to C 18 then to C16 and then to ground. This can’t be correct as pin 18 is full Vcc and if it went to ground this would create a dead short. I think what the schematic is meant to show is pin 18 going to the switches , it should not be connected to C19 and the rest, you can check it out maybe I don’t have it right.
The transmitter performs perfectly and with a really good clear sound, nothing is missing at all. Like I said earlier for comparisons, I have many different types of transmitters and have been a hobbyist with home broadcasting since 1975 and actually earlier.
I am very happy with the whole house transmitter set up. I get a lot of self satisfaction out of working on these projects. I do run it in conjunction with a 20MW amplifier not shown; I get good range with a simple dipole antenna in the attic
Again, thank you very much for allowing me to share with you my accomplishment on the part 15 web site.
Here is the link of Photo bucket which I have posted 11 pictures. I hope you get only the transmitter pictures and not the ones of my girlfriends or me putting in a sump pump etc! or the entire photo bucket thing, I tested these and only the pictures come up so hope that works the same for you.
Once in a while when I clicked on these the picture came up in the left hand upper corner and some advertisement in the main screen, if that happens to you just close it out and try it over, I don’t know if it’s a quirk or if they have photo bucket set up that way-
http://wholehousefmtransmitter.com/resources/fm-transmitter-schematics.pdf
This schematic link shows the BH1417F as an RF something or other the seller put that number in it means nothing, it’s a BH 1417F
Radio Joe!
Wow! That's beautiful work Radio Joe! You ought to sell these.
With your mods and dipole, what is the range on the xmitter?
That is a super job on the construction and also the photography and thanks for sharing.
I noticed on the schematic that there is no filtering on the output to the antenna. Have you observed or do you expect any problem from this?
For range I dont have a problem making the "200" feet.... for filtering I use this:
http://info.tactnet.co.jp/cgi-bin/soshin/eprodetl.cgi?pf=0206&pm=0206&pn=GFWB3
I would write more but I have to get back to the transmitter room!
The filter I showed in the last post is the "through hole" one available from SHOSI, here is a ebay listing from some very nice sellers I have worked through which offer the same filter chip using SMA connectors.
You can purchase F59 adaptors on eaby to match the smaller SMA connectors.
The version of the filter this seller is marketing is the SMD version monuted on a PC board with the SMA connectors installed. They do a very nice job on the construction of this filter package. It is intended for use "in line" out of the oscilliator, it is not a high power filter. It is made for oscilliator type transmitters operating at 50 MW or less. Thsse filtes have been around for a while but have been very hard to find. I would recomend you stock up now if these interest you. But dont buy them all because I still want some!
Radio Joe
It IS a beautiful job!
Part 15.US definitely needs you, Radio Joe!
I have not been on here because of numerous
life challenges that are too obnoxious to mention,
but I had to come out of the woodwork for this.
Bruce, MICRO1700, and all of the past "Dog Radio" stations
First, hi Bruce...we're saving your place at the table.
Joe,
It appears that you belt sanded the Bud box to give a satin finish. Just curious if this is what you did.
I have used a DA sander with 400 grit to do this. Also have used sodium hydroxide but that gets messy.
Neil
Great work and a nice project! Thanks for sharing!
I have 2 of those boards and I didn't know that the pre emphasis wasn't for the U.S. standards. You know that I'll be changing a couple of caps..
One of my boards sounded "scratchy" or a bit off frequency. I tweeked L1 a little and it seemed to clear it up. I didn't have a frequency counter handy to verify that..
Welcome to the mix!
Good to see ya, Bruce. I sent you a PM a while back. Did you receive it?
Thank you for the compliments again!
On the “finish” of the aluminum box, first of all it’s a Radio Shack box. I bought a few of these some time ago and the earlier boxes were pretty rough cut boxes.
The new run of these boxes are really precision cut boxes and fit together really well. Needless to say,I stocked up before they change suppliers!
Now on the “finish” well after drilling out the holes for the switch, LED, audio jacks, volume control, power and antenna jack and doing so very carefully, it’s still easy to create a few scuff marks.
I always want to make my projects look as good as possible so the first thing I do is take a razor blade and slice off any burs which the drill or reaming tool has left. These are usually on the inside of the box but can be on the outside also. Then I take a countersink tool and by hand turn the tool a few times in the drilled out holes to slightly put a finish taper on the drilled hole.
Now for that finished look: What I do here is not use a belt sander, but instead ill use 3M Scotch (Scotch bright?) abrasive scrubbing pad. The green colored one.
It’s the material that you use to scrub pans with etc, green in color and abrasive.
Now you can’t just take the Scotch bright and start rubbing on the aluminum metal, it will cut the aluminum to shreds and leave some bad marks, so what I do is first put some WD 40 on the scrubbing pad to lessen the effect of the abrasive pad. Then lightly and in a uniform fashion, slide the pad over the aluminum at an angle and with back and forth movements but at the same time, slight forward movement so as to keep moving the pad from one end of the box to the other.
Then when I have a nice consistent finish going one direction ill do the same procedure in the opposite direction (angle) to create that “cross hatch” pattern. I will repeat this process over and over each side and all sides until the finish is consistent.
After I get a nice finish, then ill apply some more WD40 on a paper towel and remove all the “dead” aluminum on the metal. It comes off as grayish stuff on the paper towel.
If I’m not satisfied with the finish or I want to get a smoother finish, I will then repeat the process but I’ll use dish soap and water, the soap provides cleaning and lubricant and tends to polish as you go.
If you just want to do the soap and water with the scrubbing pad first, that will work too, all depends on how “butchered” up the project box is after a person is done drilling holes! If you have some deep marks you will want to use more abrasive action. If your really have some deep cuts, then you will need to use very fine sand paper and wet sand to get the cuts out before going for the final finish
I should mention I use the same piece of abrasive pad from start to end, because as you use the pad it becomes less abrasive and provides an even smoother end result!
Now when you are really satisfied with the appearance, I coat the aluminum with spray silicone, the lubricating stuff, silicone provides a nice long lasting protection against oxidation and also puts a nice shimmer on the metal. Just apply a little bit and use a soft piece of cloth to remove the excess until dry.
I have also gone over the finished box with a very light coat of WD 40 instead of the silicone, your choice.
No matter what you use just don’t empty the can on the project!
Now once the box has its new appearance, you mount all the components, but better be careful, one slip and you have a mark on the the box and you just can’t go back touch it up unless you remove the stuff you just installed, unless the mark is on the top or bottom or sides.
When you work on the project box its best to set it on a nice soft clean towel or something so it doesn’t get scratched up when moving it around. It doesn’t take much to put a mark in the aluminum.
If anyone isn’t sure about what abrasive pad I’m talking about just let me know but I’m sure you know what I’m referring to. Also I just use a small piece of the pad as I work.
By the way, the screws supplied with these boxes are just common straight slot screws, they are not very attractive, so I don’t use them, I use a nice Phillips head decorative screws and epoxy a small nut on the back side of the box rather than use sheet metal screws that are provided.
Hope this helps, I would write more but i have to change the 8 track tape in the main transport! 🙂 Have a good one!
Radio Joe
Your work, Radio Joe, is superlative!
The physical appearance, inside and out, is absolutely neat and organized.
I'm just about to do some equipment building, and I think I'll have your example in mind as I go about it. Maybe I can do a neat piece of work also.
I do have a way of excusing a few shortcuts.... I like to believe that I could come back later to "upgrade" the work, which means, "finish the job".
Thanks for the great words, Neil!
After I get through all of this
stuff, I'll be back on here all
of the time. It's going to
take a very long while.
To radio Joe: Thank you for the PM!
But there's only one problem. I don't
know what a PM is. Is that a personal
message, like E-mail? If so, I could
have missed it. Anyway, if you let me
know, I will look for it. That sure was
nice of you.
Bruce, The Original MICRO 1700 and all of
the "Dog Radio Stations."
My question about the "PM"
should have been to 12vman,
and not Radio Joe.
Opps.
Sorry about that.
Bruce