Cheap 2m transverter for 6000 series

Doug Hall

Recently I purchased a 2m transverter board from UT5JCW. He sells them here:

http://transverters-store.com/144mhz.htm

You have to supply your own case and connectors, but the price (currently $80 US including shipping) seemed reasonable, so I ordered one. It arrived a little over a week later, and this past weekend I mounted it in a Bud box and hooked it to the transverter output on my Flex6300.

It works quite well so far. I am getting approx. 10 watts out on 144.2 MHz, and receive sensitivity seems comparable to my Kenwood TS-2000. I have not done any comprehensive measurements (noise figure, TX IMD, etc.) but will get around to that soon. In any event it seems like an inexpensive way to get 2m capability on your Flex.

One downside is that the 116 MHz LO is provided by a regular crystal oscillator circuit, not a TCXO or OCXO. I measured 115.998 MHz, but it seems fairly stable. The frequency error can be taken care of in the SmartSDR transverter setup.

There is no manual, just a single sheet containing a schematic and a list of connections. The other side of the sheet is in Russian. This board is not meant for use with radios that do not have a transverter output. Ideally you need a radio that can put out a 28 MHz signal in the 0 to +10 dBm range, so it works fine with the Flex.

Undoubtedly there are better transverters from vendors such as Elecraft, Kuhne, and Down East Microwave, but even the cheapest of these is 5X the price of this one. 

73,
Doug K4DSP

Jim Jerzycke

Good find!

His relay-switched LNA's look pretty good, too, with good specs at about half the price of the "Name Brands".

73, Jim

Doug Hall

This is a follow-up to my original post. I finally got around to measuring the TX IMD with the UT5JCW transverter. A photo is attached. Unfortunately it doesn't look very good, with third order products down only about 18 dB from either tone, or 24 dB down from PEP.  This is at the 5W level. Lowering the power to 1W helps a bit but not significantly. [EDIT: I rechecked the performance at 1W and it is actually about 6 dB better, so I guess that's significant.] Adjusting the PA bias doesn't help much either. I've verified that the TX IMD of the Flex6300 transverter output on 28 MHz is quite good - 3rd order products are barely visible, so my driving source is clean. 

I've emailed UT5JCW so perhaps he will have some suggestions. [EDIT: He suggested lowering the power, and mentioned that this transverter costs 1/5 of the competition.] This would not be an issue on CW, but if you care about a clean signal on 2m SSB you might want to save your pennies and get something better. Speaking of something better, has anyone ever measured the TX IMD on the DEMI or Elecraft 2m transverters?

73,
Doug K4DSP

Jim Jerzycke

QST ran a review of the 2M Elecraft unit in October 2004.

3rd-order IMD was 30dB down from the peak, and 5th-order was ~44dB.

In January 2006 they tested the DEMI 144-28 HP unit. 3rd-order was -25dB and 5th-order was -50dB.

73, Jim

Doug Hall

Thanks Jim. Wow, neither one of those is particularly stellar either, eh? I would have thought the DEMI would have been better than that.

Maybe it explains all the splattering signals I hear locally on 2m SSB when the band is open.
73,
Doug K4DSP

Simon Lewis

jeez I hope no ZL's in Christchurch buy those! 

Simon Lewis

If you want a good performaning transverter they cost money - I have played with a lot of them over the years - now I only use one brand - nothing else comes close - not cheap - but in Europe nothing else will handle the high signals in contests - I have a stack of 144,432 and 1296 plus switch - they ace anything else in terms of performance and represent decades of research by Michael DB6NT. 

http://shop.kuhne-electronic.de/kuhne/en/shop/amateur-radio/converter-transverte/transverter/

Jim Jerzycke

QST tested the Kuhne 2M transverter in November of 1997.

3rd-order was -32dB from peak, and 5th-order was -46dB.

At that time they cost $890. SSB USA has the "MKII" version for the same price, $890.

I would have thought that price would have doubled in 18 years!

73, Jim

Simon Lewis

had a brainwave!

if you're looking for a reasonable priced tvtr in a kit try G4DDK 

http://www.g4ddk.com/Anglian144v1_1.pdf

Same does kits and preamps too 

And they perform

Cheers

Simon ZL4PLM

Doug Hall

This is an update on the $75 transverter from UT5JCW. I've been using it successfully for a while now, and it has turned out to be a pretty good solution for those looking to get 2m capability on the Flex.

When I first got it I was disappointed in the transmit IMD performance. Above 5 watts output on SSB the signal wasn't very clean. I didn't want to add to the multitude of dirty signals on 2m SSB. But I found that down at the 1 to 2 watt level the TX IMD was quite satisfactory, and in fact about as good as the claimed values for the more expensive 2m transverters. I picked up a used RF Concepts 2-217 amplifier which is spec'd for 2 watts in and 170 watts out. Driving it at the 1 watt level I get around 150 watts out, and I'm quite pleased with the performance. Total investment including the amp was $225 (I lucked out and got a free 13.8V 40A DC supply) plus the time it took me to mount & wire the transverter board in a case. It hears a 0.1 uV signal from my HP-8640 with no problem.

No doubt the Kuhne or DEMI or Elecraft is of higher quality, but this setup works quite well in my application.

73,
Doug K4DSP

Ken Hansen

Doug, We're two years out from your initial report, any updates? The seller has lowered his prices, and now offers the transverter with attenuator board assembled in a case for $100+15 s/h. Others have reported success using the assembled version with the Flex 6300 after bypassing the attenuator board. Thanks, Ken, N2VIP

Doug Hall

Hi Ken,
I continue to use my transverter with the 6300 and have had no problems with it. In addition to CW and SSB I have also used it for meteor scatter work using WSJT. I've even used it on FM a few times.

My 2m needs are fairly light, so it's fine for me. I suppose the hardcore weak signal guys would opt for something better, but I'm quite happy.

I think if an assembled version with an enclosure had been available when I got mine I would have gone that route. I had to round up a case, drill holes, mount the board, etc. That would have been worth the extra $25 to me.
73,
Doug K4DSP

Ken Hansen

Thanks! My desire would be to use the transverter output on the Flex, so I'll have to bypass the attenuator board, but that appears to be a trivial exercise. 73, Ken, N2VIP

Robert - KV4JO

Hi Doug,  I have been considering using a transverter on my Flex 6300 also.  Your comments and the comments of others are very helpful to understand what I could be getting before the fact of making the purchase.  So thanks to all for the comments here in the Flex Community.

BTW, did you use the 144 / 28 model or the 146 / 28 model?  Kindly confirm.

73's to all,
Bob, KV4JO

Doug Hall

Hi Bob,

I got the 144/28 model. With the Flex transverter output you can cover the whole 144-148 MHz band with that model.

73,
Doug K4DSP

rich

I have one on the way with the attenuator board in it , will i have to bypass it or will it work with the transverter  out put.?

Doug Hall

You'll have to bypass the attenuator if you want to drive it with the Flex transverter output.
73,
Doug K4DSP

Ken Hansen

As I recall, the vendor offered directions to bypass the attenuator, now he also offers the transverters without attenuators if you aren't interested in hacking into your transverter.

rich

i dont think it will be a big deal   been in the communications 25 years and ham for over 50     thanks