[amsat-bb] Potential 23cm FM transmitter

Thu Feb 1 02:10:46 UTC 2018

Below is the translation of the article, if anyone's interested.

73,

Mac / AE5PH

A 23cm narrowband FM homebody transceiver
By Michel Lips, PA7ML

I have been active on the U-SHF frequencies for several years as an ATV 
driver. For a long time I also wanted to work in phone on those high 
frequencies. Now you can buy a well-known brand transceiver and place a 
module in it to be radioactive at 23cm. No matter how beautiful these 
shopping boxes are, that is not the challenge of the radio hobby for me. 
With some research on Google I discovered the website of Bas, PE1JPD. 
There I found a kit for a 23 cm NBFM transceiver working from 1240 to 
1300 MHz. The transceiver offers, among other things, simplex and duplex 
settings.

I am a less experienced electronics manufacturer. I also did not follow 
any training in this field. However, in recent years I have built some 
small radio hobby projects, but no self-built FM transceiver. I finally 
purchased the kit. All parts have been collected and checked by me. The 
construction instructions are well described. Experiences are exchanged 
on various forums and websites.

First, I soldered all SMD components on the underside of the PCB. A thin 
soldering iron and a loupe with lighting should not be missing. Then I 
placed the top according to instructions according to instructions.

For the parts that were unknown to me, I went to look up the specs on 
the internet to understand the operation and the connections. With my 
print layout I had to remove some parts and then place a purchased TCXO.

Then drilled holes in the HF can and soldered the print to the can. Then 
the wiring is applied to the transit C's to the LCD, shift switch, 
rotary encoder, volume on / off button, microphone and voltage 
connection. I had not yet made the wiring final; I finally did that when 
installing a transceiver housing.

Then put tension on it. There were no bangs or smoke plumes, but the 
frequency of PI6NOS on the LCD. The sending also worked. But just went 
to good friend Willem, PE1EZU, to do some measurements. The power meter 
hole 400 mW and a deviation of 2 hertz. With a 23 cm ATV transmitter 
with a dBm attenuator set the Murata band filter and the Toko coils for 
the 63 MHz mid-frequency. This went less well. When visiting the Leo Bak 
room of PI4RCG with Bas, PE1JPD, the designer quickly noticed the 
inconvenience. The Toko coils and discriminator were incorrectly 
soldered. The Toko coils are connected with a bypass to ground and the 
discriminator is removed and replaced by a regular yellow mid-frequency 
coil with a 156 hp [pF] C.

One of the Toko coils had a crazy ferrite core. By placing a hair out of 
a paintbrush on the side, the ferrite core could be tuned back to 
normal. Furthermore, I have applied the modifications of Remco, PE1FYM, 
and what I found to updates on the website of PE1JPD. A Peiker 
microphone completes the construction package.

Then the first connection was a fact at the location of PI4RCG to PI6NOS.

Via eBay, I found a provider of cheap and beautiful housing in Bangkok. 
You buy there for about 20 euros excluding 20 euros shipping this metal 
box. I applied the HF-tin and the power supply to an experimental 
circuit board and built it into the metal box. To complete the project, 
I want to build a power module and pre-amp with, among other things, SMA 
relays in the same kind of metal box.

There are radio colleagues who find these kinds of projects difficult. 
On the one hand
inexperience with electronics building projects or having little or no 
SMD solder experience. I want to encourage radio amateurs to participate 
in a DIY project. It is namely educational and fun to do. In addition, 
it does not have to be finished tomorrow, if you time and sentence you 
get the job done in your radio hack. If you do not have any measuring 
equipment, then surely a radio friend / radio club has.

Lima-SDR is a comparable building package, but then for HF. You will 
also find a lot of information about this on the web. See also the links 
below.

http://www.pe1jpd.nl/

http://www.zendamateur.com/viewtopic.php?f=14&t=15109

http://chevalgrp.com/standalone.php

http://www.lima-sdr.nl/tiki-index.php

http://limasdr.blogspot.nl/?m=1

On 01/30/2018 11:14 PM, Brad Brooks wrote:
> Mac, the arrival I was referencing started on page 20 of the Jan 2018 issue—a number of pages back from the region you quoted from.
>
> The links at the end of the article point to the following site of Bas PE1JPD, who has a nice single board FM unit that has potential. Looks like he offers his kits for about 158 Euros+shipping: http://www.pe1jpd.nl/index.php/23cm_nbfm/
>
> 73 Brad WF7T
>
> On Jan 30, 2018, 7:47 PM -0600, Mac A. Cody <maccody at att.net>, wrote:
>> This is my third attempt to post this message.  It seems that the AMSAT-BB
>> blocks messages with JPEG attachments.  Below is a Google translation of
>> the article on the 23cm transceiver inDKARS magazine.
>>
>> 73,
>>
>> Mac Cody / AE5PH
>>
>> VHF-UHF-SHF News
>> This month provided by Hans van Alphen, PAØEHG
>>
>> Nice new transistor for 23 cm PA
>>
>> Since the beginning of this year NXP has a nice power LDMOS transistor
>> in the range for the 23 cm band.
>> The transistor type: MRFE8VP13350 assumes pre-matched adaptation and is
>> designed for industrial, scientific and medical applications. The
>> transistor is capable of supplying 350 watts in the frequency range 700
>> to 1300 MHz, which is also ideal for our 23 cm band.
>> With a typical LDMOS supply voltage of 50 volts, approximately 10 to 14
>> amps is required to get the 350 watt output with a control of 8 watts, a
>> comfortable 16 dB gain.
>>
>> Italian Technology Broadcast offers 490 Euro ex VAT a module for sale
>> consisting of a built pallet with all parts on it and a copper base of
>> 9.5 mm thick that needs to be mounted on a cooling plate.
>>
>> Further information and how to order this unit can be found via:
>> http://vhelectronics.sk/index.php/en/rf-modules-and-boxes/alx-350-detail
>>
>> For those for whom this power is not yet sufficient, NXP has also
>> announced a bigger brother, the MRF13750H, which can deliver an output
>> of no less than 750 Watts in the band from 700 MHz up to and including
>> 1300 MHz. With almost 20 dB gain, approximately 10 Watts is sufficient
>> to send the transistor. This transistor will probably soon be on the
>> market and possibly also as a complete one
>> power pallets become available. Data from this transistor can be found at:
>> https://www.nxp.com/docs/en/data-sheet/PRF13750H.pdf
>>
>> 70 cm EME with only 10 watts
>> On 2 December 2017, the M6EBQ succeeded in making a 70cm EME QSO with
>> DL7APV with only 10 Watt output. The connection in WSJT was made with 10
>> W output from a Yeasu FT857 and as antenna a DG7YBN 70-17m 17 element Yagi.
>>
>> The antenna used to design by DG7YBN uses a flat folded dipole with
>> which very favorable characteristics can be achieved.
>>
>> The antenna has the property that the side lobes at the back are very
>> well suppressed and thus a very good front-rear ratio for the length of
>> this antenna.
>>
>> With 3.63 meters in length and a gain of 17.3 dBi and a front-back ratio
>> of no less than 38 dB, this is also a very suitable antenna for
>> contests. Of course, therefore, there is also little noise picked up and
>> the antenna is also very suitable for moonbounce.
>>
>> Information on how to make this antenna can be found at:
>> http://dg7ybn.de/432MHz/GTV70_17m.htm
>>
>>
>> On 01/26/2018 01:43 PM, Brad Brooks wrote:
>>> For those who receive the DKARS magazine, there is a very interesting article. The transceiver described is for ATV, but it looks like like it will tune to the AO-92 uplink frequency. Seems to put out 400mw FM out. I am not able to take time now to review deeper (stealing away from work) but I look forward to parsing through the schematic/links this weekend. I am forwarding this notice for anyone who will be able to get there sooner. I think there is some potential here, and I would like to know other’ opinions.
>>>
>>> Www.dkars.nl
>>>
>>> 73 Brad WF7T
>>> Nashville TN EM66
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>>
>> _______________________________________________
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>> Not an AMSAT-NA member? Join now to support the amateur satellite program!
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions expressed
> are solely those of the author, and do not reflect the official views of AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb