TR-35 group/forum

Do you have a question about choosing a radio, installing an antenna, or are you simply seeking advice about getting started in QRP and field radio? This is a place where you can ask your questions and seek guidance from a wide variety of radio enthusiasts. No questions are too simple. You will be treated with respect here.
Posts: 12
Joined: Mon Jun 13, 2022 6:42 pm

Re: TR-35 group/forum

Post by KB4VU »

Hi Brian,
Thanks for the reply. Wow, right there on the first page of the manual. Thank goodness for this forum for dummies like me who don't read the manuals. This was a fun build and even more fun to use in POTA activations interfaced with my Qrp Works Sidekar Extreme for logging contacts.
I have a few more qrp rigs but the TR35 is second only to my KX3.

Thanks again Brian.
73's Frank KB4VU
Posts: 2
Joined: Mon May 22, 2023 6:14 pm

Re: TR-35 group/forum

Post by kx9rt »

I just ran across this thread looking for a discussion on the TR-35. I received and built mine this past month. The build went great and very happy with the features as already highlighted in previous posts. There are a number of quirks and opportunities for improvement though.

- The volume is VERY VERY loud. I tried various headphones with similar results realizing that different phones have different sensitivities. The useable range is maybe the first 10% rotation of the knob with my headphone and antenna setup. A strong signal likely could cause hearing damage. I modified in the resistor divider R2 on the audio amp input (~200k fixed resistor instead of the 1k).

- AGC distorts on strong signals. Understood this is basic rig and has limitations of controlling IF gain. Remedied by twiddling with the RF gain. The Elecraft K1 uses a similar AGC circuit, but I don't recall that rig saturating was easily.

- Sidetone level adjustment not very effective. Varying the pot doesn't change the level much. It took a little fiddling to get it to a low enough comfortable level, otherwise it can be tiring on the ears in longer sessions.

- QSK not adjustable. Maybe not a quirk and is as designed. I like semi-QSK, but full QSK can be tiring in a busy/noisy band. It would be great to hear ideas on how to create a modification for this. Without access to updating the firmware one of the control lines on the micro-controller, the next option is a HW update. I tried a shorting FET on the RX input with a RC time delay on the GATE controlled by the TR signal(configured for about 200ms). The controlled delay worked very well and matched a SPICE simulation I created, but the RX sensitivity was significantly impacted. I backed out the mod and will consider it another day with maybe a PIN diode circuit in the RX path.


Posts: 22
Joined: Mon Mar 20, 2023 4:23 pm

Re: TR-35 group/forum

Post by KQ4EHE »

I ordered my TR-35 kit yesterday, I'm looking forward to reduced back and shoulder pain, saved expenses on Aleeve. The more I operate CW, the less I want to bother with phone, the less I want to carry a radio that does a bazillion things I only use 1/10 of.

Cut weight, make up for it in s n a c k s
Wiggins N4EEL - Atlanta, GA
Post Reply