Phase Locking the G8ACE MKII Ovened Oscillator

I decided I needed to build a new 1296MHz Transverter that would be a single unit and have enough output to drive my 350W amplifier. I had a spare G4DDK2004 Transverter module but this requires drive at 96MHz for the local Oscillator. I could have built another DFS96 but that would occupy a lot of real estate. Similarily an RDDS is too large.  In my parts collection I found some G8ACE mkII oscillators, in boxes with the PLL lock boards. One was already on 106.5MHz for my EME 10368/144 xverter so I could put another on 96MHz. I ordered a 96MHz crystal cut for 60C via G4HUP. Putting it in the unit and running the Calibration produced the following:-

The TP1 Volts was set to 6.0V for optimum performance

Thoughts then turned to the lock board. I had no idea which software the EPM3064-4 FPGA had, so I decided it was best to reload the chip.  Originally I had used a parallel port programmer running MAXIIplus+ software for programming the chip but I no longer had a parallel Port. Some time ago I bought a USBBlaster clone from China so this was found.  I downloaded and installed the QuartusII 13.0sp1 Programmer software from the Altera web site and attempted to load . Nothing useful happened. I discovered that unlike my PIC programmer the USBBlaster does not power the target, It has to have its own power. Once that was supplied the software told me it could see the correct chip and the ref_e1_64_4.pof file was succesfully loaded to the FPGA. 

After making the connections between the boards I connected a Voltmeter to the monitor point. After applying the 10MHz reference this Voltage slowly oscillated before finally settling down at a fixed Value with the Rubidium locked Frequency counter showing exactly 96MHz

Spurred on by this success I found I had a temperature calibrated 123.75MHz crystal in the third oscillator/lock board (for 24192/432MHz). I loaded the FPGA with mwref_ww2r_3064-4.pof , set conf=101 and it locked to 123.75MHz . All I need to do now is order a 123.25MHz crystal for 24048/144

Locking the 2m Anglian Transverter to an external reference

G4DDK had mentioned it was possible to Injection lock the 116MHz oscillator of the Anglian Transverter by Injecting 116MHz into the LO port of the Transverter module. In my parts collection I found an early 116MHz DFS module, similar to the design used on 96MHz described at  at http://g4fre.com/dfs9096.pdf  except it used (10MHz * 11)+(3 * (10MHz/5)) and three 116MHz crystals. The output level was ideal at +3dBm While monitoring GB3VHF it was found to put the transverter onto the correct frequency as opposed to the free running frequency.

Having proved it worked, I then mounted the DFS116 inside the box. A slider switch (less likely to get damaged portable than a toggle switch) was used to remove the 13V from the DFS when there is no external 10MHz applied. The output from the DFS did not need disconnecting from the transverter LO input when powered off.

Anglian 4m Transverter

Having had success with the 2m Anglian I decided it was time to finish its cousin the 4m Anglian Transverter . I also put the tinplate box module  in a cabinet along with the 7W power module mounted on a heatsink on the back panel, using the same metal box from makerbase.co.uk.  A metal chassis plate was needed for the inside of the box to mount the modules on, I found some aluminium sheet on ebay that could be supplied cut to size. Note that as supplied there is a lot of "paint to paint" contact between the metal box parts, so a lot of scraping was done to get "metal to metal" contact to help screening. To further help, a piece of Aluminium angle was mounted between the back panel and the chassis plate (as can be seen in the upper picture:-

The transverter was setup so that 0.5mW from the K3 on 10m produced 6W on 70MHz, which is the ideal drive level for my amplifier which has an internal 3dB Attenuator

Anglian 2m Transverter

A while ago I populated the pcb for my G4DDK 144MHz Anglian transverter. I finally got round to putting it in the tinplate box and tuned it up. All was well, so I decided to put it in a cabinet along with the 8W power module mounted on a heatsink on the back panel. I found a couple of cheap Metal boxes at makerbase.co.uk (unfortunately they have not stocked any for the last 2 years!) A metal plate would be needed for the inside of the box to mount the modules on, I found one off ebay that could be cut to size. Note that as supplied there is a lot of "paint to paint" contact between the metal box parts, so a lot of scraping was done to get "metal to metal" contact to help screening. To further help, a piece of ali angle was mounted between the back panel and the chassis plate (as can be seen in the lower picture:-

To add heat transfer, I wanted to mount the power module directly on the heatsink rather than mount it on the back panel then on the heatsink. To do this I would need to make a rectangular hole in the back panel. Discussing this at the Malvern Radio Club, it was recommended I used a nibbling tool. I found one on the internet for 9.00 shipped. It is a brilliant tool; I can see a lot of use in its future!

As there is no conductivity between the metal parts of the case due to the paint a lot of time was spent removing paint to allow good electrical contact between metal surfaces. I also add a piece of ali angle between the back panel and the chassis plate.

The transverter was setup so that 0.5mW from the K3 on 10m produced 7W on 144MHz, which is the ideal drive level for my amplifier

The 144MHz connectors were spaced to allow an external coaxial relay to be attached with a pair of BNC to BNC male adapters. This allows use with a single antenna feeder if needed. Normally when using a masthead preamp the two connectors are used, eliminating the prospect of transmitting up the back end of the preamp

updated nov 2017

Exercising my 2300MHz NOV

After seeing the announcement that the 2300MHz NOV were finally available I decided it was time to get one. After reporting some disparities between the RSGB website and the application form (eg the website said "main address only"; the form allowed a list of portable locations) I managed to get an NOV. The issues have been corrected

 For EME operation from the USA one needed to cover 2300, 2304 and 2320MHz so a Transverter for 2300MHz was already available as written up at http://g4fre.com/13cm_xv.htm My PA using the driver stage from the Spectrian Amplifier produced 10W, I didn't have enough drive to get the full 30W.

On Thursday evening I tried a sked with G4BAO at 170km. I used my only  13cm antenna, a 25 element (the one with the horn feed) taped to a cardboard box pointing out of the bedroom window.

It was suggested to try ISCAT-A digital mode.

213800   1 -12 23.2  -65   0 *  G4FRE G4BAO                   12 10 10  4.5

213900   1 -11  2.0  -65   0 *  G4FRE G4BAO                   12 10 10  2.2

214000   3  -9 16.5  -65   0 *  G4FRE G4BAO                   12 10 10  4.5

214100   1 -10  2.0  -65   0 *  G4FRE G4BAO                   12 10 10  2.2

214200   4 -10 12.0  -65   0 *  G4FRE G4BAO R-15 R-15         22 10 10  8.9

214300   3 -10  3.1  -65   0 *  G4FRE G4BAO R-15 R-15         22  9 10  4.5

214500   6 -10 19.8  -65   0 *  RRRR RRRR G4BAO               16  3 10 17.8

It took a while to complete the QSO, aircraft reflections were non existant but we completed for my first trop QSO on 2300.2MHz. A quick try was made with G4DDK at 246km but no two way QSO

On Friday morning I tried again with G4DDK. His signals were weaker by some 5dB than the previous evening but were there most of the time. It took a long time to get a signal report exchange on ISCAT-A. 

105100   1 -15  6.5 -118   0 *  G4FRE G4DDK                   12 10 10  8.9

105200   3  -9  3.1 -118   0 *  G4FRE G4DDK                   12 10 10  4.5

105300   3 -11  5.4 -108   0 *  G4FRE G4DDK                   12 10 10  8.9

105400   2 -13 12.0 -108   0 *  G4FRE G4DDK                   12 10 10  8.9

105500   1 -12 21.0 -129   0 *  G4FRE G4DDK                   12 10 10  4.5

105600   2 -12 10.9 -129   0 *  G4FRE G4DDK                   12 10 10  8.9

105700   2 -14 19.8 -129   0 *  G4FRE G4DDK                   12 10 10 17.8

105800   4 -10 23.2 -129   0 *  G4FRE G4DDK                   12  9 10  8.9

105900   1 -11 14.3 -140   0 *  G4FRE G4DDK                   12 10 10  4.5

110000   2 -13  9.8 -140   0 *  G4FRE G4DDK -17               16 10 10  8.9

110100   2 -13  5.4 -140   0 *  G4FRE G4DDK -17               16  5 10  8.9

Signals were not "bursty" as would be produced by aircraft, so we switched to JT65c, which is good for weak, continuous signals. The QSO completed quickly:-

110400  8  -10 -1.7 -137  6 *      G4FRE G4DDK JO02          1  10

110600  5   -9 -1.7 -143  7 #      G4FRE G4DDK JO02    OOO   1  10

110800  7  -16 -1.7 -143 11 *      R-17                      1   0

111000 10  -23      -142  2   RRR ?                               

111200 10  -22      -145  4   73  ? 

The lesson learnt is that the digital mode used needs to be carefully chosen based on the received signal characteristics