The QRPer Board

A short while after building my TR-35 last month, I started noticing my RBN spots were consistently lower in frequency than where I had my VFO set. I've been able to investigate and confirm a couple of different ways that the VFO display reads ~100-180 Hz "sharp" of the frequency transmitted. I've read the frequency into a dummy load directly with a frequency counter and a scope, before that, I keyed into a dummy load with my FT-817 nearby, and then zero-beat to match, the tx was consistently under what the display on the TR-35 reads, and consistent within a few hz of what my RBN spots read. Also, I do believe the keyer speed wpm is wildly off, but that's not as big a deal.

At any rate, over the last few weeks I've tried to contact WA3RNC via the website contact form and the email attached to his QRZ profile with no response. I'm looking for an alignment procedure, if its possible, or worse yet sending the unit back to be aligned. In the interim since I've noticed the problem, I've just been tuning "up" 150hz or so to be where I want to be but I'd really like to have this where it should be. I do like this radio quite a bit and would like to have it around for a long time.

Any advice? Anyone know how to get in contact?

Hi Andrew,
I have a TR35 that has the same problem. I built it over a year ago so it is probably a low serial number.
I have not tried to contact WA3RNC so I can't help you there. I have just been compensating for the
difference, but it would be nice to have the indicated freq then same as the actual. It's a great little
radio and I enjoy using it. I just went on a family vacation and was able to do one POTA activation with it,
was hoping to do a couple more, but the family stuff kept me pretty busy.
If you do get in contact with WA3RNC and get an alignment procedure see if he will post it on the web site
or maybe you could post it here.

72's Frank KB4VU

Will do! but I'm not holding my breath at this point. Compensating in the field isn't really a big deal, but it would annoy me if it was an easy fix I could do myself if I only had the info.

The RBN spots for my mountaintopper never match my dial. Even my crystal-controlled QRPp transmitters don't line up. My old MFJ QRP rigs are way off. One is high on the low part of 40 and low in the high part!

Look at the spots on the home page snd you'll see lots of spots that don't end neatly on a zero.

I wouldn't worry too much about 200 hz!

Rick N8TGQ

If it is consistently and measurably off, I can totally understand the annoyance and would want to get it resolved as well.

I will say though, I've been on activations before (with different radios and antennas and not a lot of common variables) and seen the spotted frequency change +/- 100Hz or so during the activation without changing the VFO on the radio. In some cases it appears to be a matter of which RBN site is reporting the spot and will change back and forth throughout the activation.

I don't worry about it much because it is "usually" correct and I figure it's close enough for the hunters to find me and heck, I don't want everyone to zero-beat and call at the same time anyway.

If it is consistently off though I do hope there is some sort of alignment or adjustment that can be done to make it "usually correct" and that you'll report back here if/when you find it! Hope he gets back to you soon!

I mean, I’m not worried about tolerances on RBN, but it is demonstrably and consistently off, on every band, with every antenna, in every location. So yeah I’m a little disturbed by that, but more annoyed at the lack of communication. It’s 2023, answer your emails. ¯\_(ツ)_/¯

I just brought out my TR35 to re-check the indicated vs actual transmitted freqs. It is not off as far as I first thought in my first post. I used my frequency counter which is by no means a lab grade counter but is pretty accurate. I used my IC7300 with the passband set down to 50HZ to
monitor the TR35 xmit and to xmit to theTR35 to monitor the receive of it. The results are below.

TR35 displayed 14.050 actual 14.049966 for -34 HZ ---------- IC7300 displayed 14.050 actual 14.049980 for -20 HZ

TR35 displayed 18.070 actual 18.069950 for -50 HZ ----------- IC7300 displayed 18.070 actual 18.069976 for -24 HZ

TR35 displayed 7.030 actual 7.029979 for -23 HZ -------------IC7300 displayed 7.030 actual 7.029991 for -9 HZ

TR35 displayed 10.120 actual 10.119967 For -33 HZ -----------IC7300 displayed 10.120 actual 10.119987 for -13 HZ

I used the narrow filter on the TR35 and the 50HZ passband on the IC7300 and signals from each radio fell well within the receive passband
of the other.
I am happy with these results and think this good for a low cost kit radio.
Andrew, hopefully you will be able to get info on how to enter the programming mode to set the timebase to your satisfaction. I built a
KD1JV Tribander and it has the same problem. You go to program mode and set the timebase freq and store it. The problem is you can set
it, but there is a glitch in the firmware and it will not save it. The TR35 uses the same SI5353 chip as the Tribander so I assume it is just a
matter of getting into the program mode to set it.

Good Luck!!!
Frank KB4VU

This is great info Frank, thank you! I’ll have some free time at work to make a similar table comparing with my FT-817.

The reality of the situation is, I set up in 10 minutes and got 15 qso’s in 20 minutes at the beach yesterday. I tuned to 14063.15 and spotted myself at 14063.00 and nobody had trouble finding me.

So I should probably relax a little, huh?

Hi Andrew,
I'm glad you had a good activation yesterday. Just go out and have fun, the hunters will find you.
I looked in my log and see that I have not worked you yet, but will keep my eyes open for you and if
I can I'll hook up the TR35 and have a TR35 to TR35 QSO. It's awful hot down here now so I probably
won't be going out much until the end of Sept. I'm getting too old for the heat. I was on at a family
reunion last week in VA and took the TR35 along and slipped away one morning and went to Harper's Ferry
WVA and did an activation before it got hot. I made 22 contacts in 45 minutes using a quarter wave wire
on a 20ft collapsible fishing pole in the bed of my pickup.

72's Frank KB4VU