[VHFcontesting] [VHF] Warmup Drift Of Ukranian , UT5JCW, 222 MHz Transverters & Possible Use With FT-8

[JamesDuffey]

Pete - W7QQ and I looked at about a half dozen of the Transverters Store (Ukrainian) 222MHz transverters a few years back. One thing that we noticed was that the drift we measured, while similar to the measurements on most of the units, was quite a bit worse on one unit. I suspect that it had been assembled with the wrong capacitors in the oscillator section. So, the measurements that Steve made may not be representative of all the units available. 

The other thing I would caution about is that the drift will probably vary when transmitting, so if he can, I would suggest that he redo the measurements while running FT8 into a dummy load. 

There is some frequency compensation in FT8, so some drift can be compensated for. I am not sure how much is viable in practice, but I would think that if it is under a tenth of the bandwidth, say 5 Hz drift, but the best way is to try it and see. Worst case would be the transverters at each end of the QSO.

James Duffey KK6MC
Cedar Crest NM

> On Apr 16, 2021, at 08:32, peter h via VHF <vhf at w6yx.stanford.edu> wrote:
> 
> 0715pdt 16april2021
> A number of us in SoCal have been using UT5JCW's 222MHz transverters with good success on CW/SSB/FM from home and hilltopping/roving.
> Tim, N6GP, wondered if they are suitable for use on FT-8.
> Steve, WA6EJO, 'volunteered' to plot drift data on his UT5JCW 222MHz transverter.
> His results are tabulated below.
>    Steve, WA6EJO, did some transmit frequency stability tests using a GPSDO referenced frequency counter.
>  Some of the drift may be due to the exciter, a TS2000X, but most is from the Ukranian transverter. 
>  From 2 to 3 minutes after power on it moved -227 Hz 3 to 4 minutes -103 Hz 4 to 5 minutes -64 Hz 5 to 6 minutes -45 Hz 6 to 7 minutes -27 Hz 7 to 8 minutes -21 Hz 8 to 9 minutes -17 Hz 9 to 10 minutes -7 Hz 10 to 15 minutes +50 Hz 15 to 20 minutes +13 Hz 20 to 25 minutes +47 Hz 25 to 30 minutes +37 Hz
> 
> 
> Do any experienced FT-8 users have any comments on possible use of the transverters with data modes?
> Thanks,
> BT73
> Pete, N6ZE 
> 
> 
> 
> 
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