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The Rather Tiny DM-rowave Extravaganza


It all started with a simple misunderstanding. On the local Hannover UHF repeater, I only mentioned that the ‘Bulgarian 23 cm transverter’ got some good criticisms when Ralf DL2RLA instantly returned that he’s gonna buy one an join my order. Aha… :neutral_face: What was I supposed to do, then? I couldn’t resist and didn’t want to be a killjoy, so we were committed. My friend Lacki DC1AP and Chris DG5OAC, both local hams, too, shortly later joined the order. No need to say that 23 cm transverters were the hot topic on the repeater the following days. And it turned out that there was kind of need to re-start activity on 23: more and more local stations from then said on the band they were happy to hear our plans or that they’d just reactivate their rigs if there was activity.

The transverters arrived just the other day and I couldn’t neither keep my fingers off it nor not-tell the good news on the repeater. Wolfgang DK1HW (a dedicated SOTA chaser) offered on the repeater to give me a CW signal on 1296 MHz and I was able to copy him 59 in my inner-city shack with the transverter and its HB9CV attached in my hand over my head catching the best reflection! But he couldn’t hear me, so I packed my rucksack and went off to the local summit Lindener Berg. More a pimple than a hill but with an excellent take-off to his direction. And it’s only a 15 minutes walk from my door.

Arriving at the summit I spotted Stefan DO7OZ and his telescope right besides the DL0TY club station (kind of an overseas container) . He listened to DK1HW and me on the repeater and had already prepared a folding table to host my 23 cm test setup. :heart_eyes: My FT-290RII (I dropped the Mark2 in the other thread, anyway still hoping to gain some old school bonus points when it’s gonna come to an activation with this rig) didn’t power up and so I had to borrow Stefan’s FT-2 to make a QSO. The supplied HB9CV was directly attached to the transverter wich was connected via a thin coax to the FT-2. I was curious how this was going to work. Meanwhile DK1HW alerted his neighbouring station DK4OS. Both were an armchair copy in FM and so I got two QSOs that night, both about 15 km. It’s working, first test passed! Then the FT-2 slipped off my hand, fell to the ground and ripped the tiny piece of coax off the plug. :poop: So no SHF operation anymore, but later I got some amazing views of the galaxy through the telescope and Stefan’s brilliant explanations. That was on Wednesday.

On Saturday I was equipped with a new coax and did the first real outing, no SOTA activation though. Kronsberg (GMA DA/NI-268) is in the outskirts of Hannover and peaks at 118 m asl what is not that much but you have to take in consideration that most of the surrounding area is avout 60 m asl. I clamped the transverter to my SOTA pole and raised it up to 3 m above ground. Couldn’t give more due to the dc-cable. May consider to make a longer one… First QSOs were, again, DK1HW and DK4OS, this time with really big signals in SSB. And then in FM Chris DL1CR, a dedicated SOTA activator. However, this time he was at home in the city and making the contact with his FM HT from the attic window. Meanwhile he ordered a transverter, too, to operate in SSB rather than in FM. But it’s still on its way and hasn’t arrived yet. I also made one QSO via FM repeater DB0XY which was a good 70 km from my position. Everythig worked fine on the outing except I had the FT-857 with me, not as intended the FT-290RII. I wasn’t able to spot the issue with the FT-290 and so I set up the 857 according to VK1DA’s advice and it seems to work well.

Now it was time for a SOTA activation. DM/NS-160 Tafelberg, not one of my VHF favourites but it has a viewtower helping to bring the antenna above the trees and most of Hannover county is in LOS. We started in FM since DL1CR still hasn’t got his transverter but only his FM handie.

According to my alert, I was a bit early and even had a short natter on the announced 144 MHz FM frequency before DL7OQ was the first in my log on 23 cm, a new personal GHz simplex-ODX, 42 km. Big signal, owes me an S-meter now. DL2RLA was next operating under weird circumstances while holding the transverter and his FT-817 out his window to copy me. As a SOTA activator DL1CR knows when the time is right to show up and was my number 4. Yeah, I qualified a summit on 23 cm on the first attempt!

But more than that: On 144 I got the information Lacki finished his works to get the transverter working and was QRV. However, he lives in the city and has 20 m of RG213 between the transverter and the vertical antenna in his attic. That must be microwatting on microwave! DK1HW, DJ7OQ and me tried to copy Lacki but it was no good. I then changed to vertical polarisation and I was able to hear him in the noise. The QSO was really hard work and I even only got fragments of his callsign. However, the QSO is valid because we’ve known each other for 40 years now and I clearly identified him by his voice coming back to my call. It then took endless minutes to get his ‘31’ and rogers as he was 21 with me only when the QSB lifted his signal for a second. That’s a 5 QSOs and 184 km in total, I’m quite satisfied.



Hi Pom,

Thanks for the report, it sounds as though you have some good activity building on 23cm!

I’m sure you know this, but just to flag it up - it is possible to power feed these transverters through the coax, you just have to configure it, and provide an RF isolating “tee” at the bottom end of the coax. They really are nicely designed :smile:



Glad to hear you are happy and having fun Pom. The SG-lab transverters offer a huge amount of “bang per buck”. The guys at SG-lab should be given some kind of award because their units have had a noticeable affect on encouring people to try the low microwave bands.

Sounds like you have a nice core group that will mean you can get at least 1 QSO per summit you activate. And as you have discovered, your new activity will encourage lots of people with the gear that they don’t use often to blow away the dust and have a go at working you.



it is possible to power feed these transverters through the coax, you just have to configure it, and provide an RF isolating “tee” at the bottom end of the coax. They really are nicely designed :smile:

Oh, yes, Adrian. These tiny boxes offer a lot of options. I wanted to get on the band instantly and the easiest way was a DC-cable along with the RF vox. I’m not yet determined if I’d rather use the coax to DC-feed the transX or if it makes sense to send PTT over the coax. Additionally, the RF vox seems to perform very well, even on SSB. Maybe there won’t be no future need to apply a PTT signal at all. Let’s acti-wait :wink: and see what is the most useful option.

And as you have discovered, your new activity will encourage lots of people with the gear that they don’t use often to blow away the dust and have a go at working you.

The Scots did it, so why can’t we? Seriously, the GM microwave group is kind of a role model to me. It shows, you only need a starter and a good mixture of chasers, activators and ‘normal’ radio guys: Activators need chasers and the ‘normal guys’ need activators for keeping it interesting and not having contacts with the same stations at the same locations over and over again. Hopefully, this won’t be a straw fire and we’re gonna keep the activity up till spring, when people are more willing to be persuaded to get out and operate portably (maybe from a summit).



Hi Pom,

Noticed your reference to the power level setting on the 857. Glad it worked ok.

I used to have an ft290 mk1. If that’s the one that has failed you, you might have to reset the CPU. Use the Internal switch to disable battery backup. Then turn it back on and power up. Memories are lost but the radio should be back to normal. This fault occurs when the cr2032 cell has dropped below its useful voltage.

73 Andrew VK1DA VK2UH


Again thanks fo the hint on the FT-857. It’s highly appreciated. I did some internet research and it looked good from the first second: The FT-857 is known for producing rather small spikes on VHF and Hristiyan is convinced the transX will cope with an 857anyway. However I reduced the VHF TX Gain to a maximum p/o of about 5 W. More, I reduced the VHF TX min p/o to something less than 5 W. Now I can adjust p/o during operation, what is needed to switch from e.g. FM to SSB: When adjusted for FM, the power LED indicates ‘yellow’ in SSB. But it indicates ‘red’ in FM when adjusted for best SSB output. For my 857 this works well, adjusting for minimum p/o in FM and all fully clockwise :loud_sound: in SSB.

The issue with the FT290II was just a bad plug or socket. Somehow there was no electrical contact. Now working again. :slight_smile:



I have to give credit for the 87 power spike explanation to a post on the US microwave mailing list which I subscribed to and read avidly for some time. The power spike proble is also mentioned in eme circles, mostly in relation to the 87 series , the 847 and the ts2000. In the majority of designs, the output power setting is somewhat of an afterthought.

A brief spike up to full power is of no consequence when the radio is connected to an antenna. But when connected to a transverter or external amplifier (the use case relevant for some eme ops), alc type power limiters are very poor in terms of the output waveform if the amplifier chain under all control has enough gain to produce the high power originally designed into the chain in the first place.

Fortunately by understanding the relationship between the gain and power limit settings in the 8*7 series, you can achieve very good results and not worry about power spikes.

The ts2k seems to have no way of reducing the gain.but to be honest I haven’t examined that one in any detail. I don’t own one of those radios.

Most articles about using the internal settings menu for the 8*7 series warn users not to fiddle with the settings. Good advice. Another useful thing is to record the original settings in your logbook or somewhere you won’t lose. You can reset to the original calibrated settings before disposing of the Radio later.

73 Andrew VK1DA VK2UH


Hi Pom,
thank you for the encouragement to activate the 23 cm band. Meanwhile, I got the transverter and had some fine qso with Wolfgang, DK1HW. Today I climbed the summit Oelberg near by Wietze and it works fine on a distance of nearly 40km.
I’m looking forward having our first summit to summit qso on 23cm.
73 Chris, DL1CR


Hej Chris,

good to hear you’re now qrv in SSB! We’re hopefully gonna make the s2s still in December. I’ll have some days off work and this’ll hopefully fit your activating times. There’s gonna be a vhf/uhf s2s party in the afternoon of the 29th December (see the other mountain award scheme). I’ll be out on 2 m and 0,2 m. How about you?

I’ve recently spotted some semi-rigid cables with BNC- and SMA-plugs on ebay. Now waiting for them to arrive that I can make antennae feedlines of them. :sunglasses:



In UK there is a 23cm activity session every month, the next one being on Tuesday 19th December 20:00 - 22:30.
I try to be on a summit for these, weather permitting.

It would take unusually good propagation conditions for me to work into DM from the Welsh border (I have heard a PA0 station, just once), but there are some big stations in the South East of England who will be beaming your way in hope!

I realise that dark evenings in winter are not ideal for SOTA activating, but I thought I’d mention it!




I can clearly see you are as crazy as I am. At least in the perspective of making rather unlikely QSOs. :thumbsup:
To my mind, we’re now committed for a S2S GW-borders <> DM, even if it’s not gonna happen right on the next 23 cm-Tuesday. It’s maybe better to wait for spring and some passing-by aircraft?

I realise that dark evenings in winter are not ideal for SOTA activating

No it’s great! I’ve been out for almost every VHF Tuesday for more than one and a half years. Each one a very special activation most of the year beginning in the dark and never ending at daylight. Think I have to PM you regarding the Tuesday nights, maybe I have useful information for you.



Quick outing today on DM/NS-161 Griesberg. Rather a crap summit but I haven’t been there this year and it isn’t that far from home…
I had the recently built scrap-biquad with me to test against the OEM HB9CV. The transX and the biquad were clamped to the pole in a height of appr. 4 m. No answers to my calls on 145.450 fm what developed our regional sked frequency for 23 cm. Would anyone answer me on 23 cm if there ain’t no-one on 2 m? So I was a bit suprised when DL8OAZ came back to my call on 1296.200 ssb and gave me my first random-qso and a new ODX of 41 km on 23 cm. DK4OS joined us some minutes later (37 km).
When I was to change antennas I managed to break the DC-plug of the transX - instantly qrt on 23 cm. I dragged some local stations from the UHF repeater to VHF simplex and qualified the summit.
Now going to the pub and after return I’ll have to fix the plug to get on the air from DM/NS-001 tomorrow.



Nobody told me of the strong gusts throughout DM today.
Even more chilling at a height of nearly 1000 m asl and -3 C. I hoped to qualify DM/NS-001 Wurmberg on 23 since I had a sked with Lacki DC1AP and hoped for some of my local chasers. The s2s qso with DC1AP and DL7BF on DA/NI-268 (GMA) Kronsberg 84 km was easily made. However, sometimes I couldn’t hardly understand what they were telling me due to the strong wind noises. Then, no more stations on 23. DL1CR and DN6DM were logged on 144 MHz FM with my HT and rubberduck. Getting cold I packed my things and sloooowly stepped down the steep and icy stairs.