Tag Archives: Penntek TR-35

Many thanks to Michael (N7CCD) who writes:

Hi Thomas!

I just watched your last activation video (very fun by the way!) using the TR-35 and thought I’d share really quickly my solution to the lack of an SWR indicator.

It was a cheap (and fun) $5 for the kit, build project I did with my brother, N7BHP, while visiting him in Mexico. It was actually the first little precursor project to building the TR-35 while on that same trip.

We picked up three (one for me and two for my brother) Pacific Antenna Mini SWR Indicator kits, and some cheap cases off of Amazon that just fit the meter. Of course, we had to add the BNC connectors also.

The kit is a 50ohm dummy load, and the LED lights up if the SWR is above 2:1. I’ve actually used this to tune my AlexLoop with the TR-35. When the light goes out, you’ve hit 1:1. I’ve found the LED on this kit to be more sensitive than the AlexTune light on the antenna.

I modified my kit to eliminate the switch. The way they have you build it is to leave it inline with your antenna, and just flip the switch from ‘forward’ to ‘reverse’. To save space and fit into the little plastic case, we jumpered where the switch would be so it stays in the ‘engaged’ position. I then just put it in at the very beginning of my setup to ensure the SWR is good on my antenna, then take it out of the circuit completely when using the radio.

It’s small enough to just live with my TR-35 at all times.

Hope all is well!
Michael -N7CCD

I love this, Michael. I think I might have to build one as well. Looks like a fun, inexpensive build that’s actually quite practical! Thank you for sharing!

Accessories, Antennas, CW, Field Reports, News, Portable, POTA, QRP, QRP Radios, Videos

New Penntek TR-35 Field Kit, Canine Welcome Party, & Brilliant 20 Meter POTA Conditions!

January 27, 2023 Thomas Witherspoon 9 Comments

There are few things that make me happier than radios and pets. On Saturday, January 7, 2023, I got copious amounts of both.

On the way back to the QTH, I stopped by Table Rock Fish Hatchery (K-8012) for a nice, leisurely POTA activation.

En route to Table Rock I gave some though to the antenna I might deploy. In the end, I decided I’d once again set up the Chelegance MC-750.

There was no question which radio I’d use: it’d be the brilliant Penntek TR-35 packed-up in its new field kit!

Table Rock Fish Hatchery (K-8012)

Table Rock Fish Hatchery isn’t open on Saturdays, but that really isn’t a problem because the picnic area where I set up shop is open 24/7.

And the best part about Table Rock? The welcoming committee…

These two dogs are so incredibly sweet and always a highlight of activating Table Rock. You may have seen them in my previous field reports and videos. Continue reading New Penntek TR-35 Field Kit, Canine Welcome Party, & Brilliant 20 Meter POTA Conditions! →

Accessories, News, Portable, QRP Radios

Sam sources a larger tuning knob option for the Penntek TR-35

November 8, 2022 Thomas Witherspoon 3 Comments

Many thanks to Sam Duwe (WN5C) who writes:

John (AE5X) had suggested a while back finding a larger tuning knob for the Penntek TR-35.

I was striking out in finding one that fit but had to put in a Mouser order and thought I’d give this knob a shot (Mouser # 706-11K5013-KFNB) and I really like it!

I accidentally bought the gray version and had to paint it black. It’s shiny because of the clear coat and rough because of sanding and because I’m apparently awful at painting, but I find that it fits with the plastic bezel of the radio.

With the optical encoder it really glides, and totally changes the feel of the radio. Pretty good deal for $2.36.

Thank you for the tip, Sam!

Antennas, Guest Posts, Homebrew, How To, News, Portable, QRP

Sam builds a tiny tabletop HF antenna

October 30, 2022 Thomas Witherspoon 17 Comments

Many thanks to Sam Duwe (WN5C) who shares the following guest post:

A (surprisingly good) tabletop HF antenna

by Sam Duwe, WN5C

I recently built a tabletop QRP HF antenna for 17 and 20 meters, in the spirit of the Elecraft AX-1, so I could operate at lunchtime on the campus where I teach. My wants were something small, that would fit in my work bag, that didn’t require a tuner, and could work on a couple of different bands. But on a lark I decided to attempt a POTA activation at Lake Thunderbird State Park (K-2792) pairing this antenna with my Penntek TR-35 QRP CW transceiver. I figured I’d maybe get one or two QSOs and then switch to a long wire in a tree. But what happened amazed me.

I talked to seemingly everyone. Beginning at 9:00 AM September 26th I worked both 17 and 20 meters for an hour and a half and made 37 contacts from across the country. I even had a Swiss guy call me back on 17 but he faded before we could finish. This antenna, at least as a CW POTA activator, works. Granted conditions were very good, but I’ve replicated this multiple times in the past few weeks, just recently at a picnic table in the parking lot of the Route 66 Museum (K-8644) in Clinton, OK (there is quite a thrill in urban activations).

It has also reasonably low profile and very quick to setup and take down. It is also quite a conversation piece when I set it up at school. I elevated the counterpoise by attaching it to a nearby oak and an interested undergrad sheepishly asked if I was listening to the tree!

The build is pretty simple. Physically the antenna consists of a small painters pole from Walmart and an old tabletop camera tripod. I found a nut that fit the screw portion of the tripod and hot glued it into the orange connecting section of the pole. That way the tripod can then be screwed onto the pole. The RF parts of the antenna consist of a 38” telescoping whip that I scavenged from the rabbit ears antenna that came with my RTL-SDR. It connects using the original connector which was hot-glued into a hole I drilled into the top of the painters pole. I found similar small 3 or 4-foot whips from AliExpress for cheap and these would probably work fine.

I then soldered a long length of speaker wire that was wound into two coils: the top for 17 meters (24 turns) and the bottom for 20 meters (25 turns plus the former 24-turn coil). The speaker wire was the soldered to the center of a BNC connector which I hot glued and taped to the pole. I soldered a short piece of wire from the shield of the BNC for the counterpoise and added an automotive spade connector to attach to a 17-foot length of wire. I also included a switch between the coils and the BNC connector to select either just the top coil (17 meters) or both coils (20 meters) using solder, hot glue, and tape. I then covered my shame in silicone tape.

The most time-consuming aspect of the project was tuning the antenna. It required trial and error to first tune the number of turns on the 17-meter coil and then the 20-meters coil. I extended the counterpoise (for me it’s best when slightly elevated) and the telescoping whip. I performed the tuning with the whip not fully extended to give room to tune in the field. Using a nanoVNA was useful here, as was soldering a pin to the wire to poke through the wire at various parts of the coil to find the best SWR.

In use, the antenna can be affected by both body capacitance and how the counterpoise is situated, so I found that an in-line SWR meter was helpful in making sure all was well. Once set up it is easy to fine tune by just adjusting the whip length. 1.5:1 SWR is about how well I can tune on average. Obviously if you have a tuner you would just have to get it close.

There are a million variation on a small base-loaded vertical antenna, and you can definitely improve upon this design. And, besides the super well-built and elegant AX-1, QRP Guys sells an interesting looking kit, and there are some good 3D printed designs I might want to try out. But regardless how you go about it, it might be worth giving a tiny antenna a shot.

72, Sam WN5C

Articles, CW, Guest Posts, Homebrew, How To, News, Portable, QRP

Sam builds a compact external speaker and 200 Hz filter for the Penntek TR-35

September 23, 2022 Thomas Witherspoon 21 Comments

Many thanks to Sam (WN5C) for sharing the following guest post:

A Compact CW Filter and Speaker Build for the TR-35

by Sam Duwe, WN5C

I recently built a Penntek TR-35 and, like seemingly everyone, I love it.

Once the rig passed the smoke test I was having too much fun and wasn’t quite ready to put away the soldering station. I had two non-essential wants for this project: a narrower CW filter for listening comfort, and an external speaker. Here’s a quick description of how I crammed both of those into an Altoids tin. Nothing is new or groundbreaking here, but it has been a fun and useful project for me and hopefully will give some inspiration for others.

The Hi-Per-Mite

The heart of the project is a Hi-Per-Mite 200 Hz CW filter, designed by David Cripe NM0S, and sold as a nice kit for $28 by Four State QRP Group. Hans Summers G0UPL uses the circuit in the QCX so many will be familiar with the filter’s sound. It’s nice and narrow with no ringing, and makes using my base station (a Kenwood TS-520 with the 500 Hz crystal filter) a joy.

To be clear, the existing narrow filter in the TR-35 is great, but I like the option of going narrow(er). It’s a Pixie-level build difficulty so it should come together in an easy couple of hours. I originally built mine in an Altoids tin using inspiration from Phillip Cala-Lazar K9PL’s review and it worked very well. It sips current and is powered by a 9-volt battery. With a DPDT throw switch connected to both the audio path and the power you can easily switch the filter on and off.

The Speaker

A neat aspect of the TR-35 is that there is a lot of audio gain so you can drive a non-amplified speaker. I have a little Bluetooth speaker that does this trick when I want to use CW to annoy people, but I figured if I’m already hauling an Altoids tin to the field maybe I could get it to talk, too. I looked around my junk box and found a broken Baofeng speaker mic and salvaged the speaker. It works really well: a robust but comfortable volume.

I’m sure any little speaker would do the trick… nothing fancy here, it gets hot glued it to the lid of a mint tin after all.

The Build

After I built the Hi-Per-Mite here’s what I did: first I ate a tin of Altoids and felt a little sick. Then I drilled some holes. The one on the left is for the audio input, the one on the bottom for the headphones (both of these are 1/8” stereo jacks), and two on the right for two mini DPDT switches. I also drilled holes in the lid for the speaker sound to come through. I gave the tin a good sanding and tried to remove sharp edges, and then sprayed the lot with black primer and spray paint.

Continue reading Sam builds a compact external speaker and 200 Hz filter for the Penntek TR-35 →

Accessories, How To, News, Portable

Fold-out feet for the Penntek TR-35

September 20, 2022 Thomas Witherspoon 10 Comments

I must thank my buddy John (AE5X) for this excellent tip.

I was watching one of his YouTube videos some time ago and noticed that he added fold-out feet to his Penntek TR-35.

Like John, I appreciate my radios sitting at a bit of an angle as I operate and these fold-out feet looked like the perfect addition to my TR-35.

These feet are designed for laptops which are much heavier than the TR-35 or pretty much any similar field radio.

They arrive in a small package with an alcohol wipe to clean the bottom of the radio. The adhesive pads on the feet are made by 3M and high quality. I doubt they’ll ever fail. Since they’re designed to allow airflow under a hot laptop, I believe the adhesive should withstand hot summer days in the field as well.

Continue reading Fold-out feet for the Penntek TR-35 →

Articles, CW, Kits, News, POTA, QRP, QRP Radios, Reviews, SOTA

A comprehensive review of the Penntek TR-35 four band QRP transceiver

June 12, 2022 Thomas Witherspoon 20 Comments

The following article originally appeared in the April 2022 issue of The Spectrum Monitor magazine:

“Look at this, Tom! Only the stuff I need and nothing more,” cheerfully noted my good friend and Elmer, Mike (K8RAT). It was Field Day two decades ago, and Mike was gazing at his TEN-TEC Scout. I glanced over, and agreed. “So simple and so effective,” Mike added.

I’ve never forgotten Mike’s sage words. That Scout (Model 555) was about as simple as a then-modern HF transceiver could be: it had a total of three knobs––one for AF gain and IF bandwidth, one for RIT and Mic gain, and an encoder. It also had three mechanical switches on the front: one for power, one for TUNE and NB, and one for CW speed and RIT. It also had an analog SWR/power meter. The Scout used plug-in band modules for each HF band and featured a large segmented bright green LED frequency display that was characteristic of so many TEN-TEC rigs of the day.

And Mike was right. For those of us who appreciate radios with a simple, uncluttered, and an almost utilitarian interface, the Scout was, in vintage parlance, “the bee’s knees.” And that the Scout also performed beautifully was just icing on that cake.

When the Scout first appeared in 1994, embedded menu options and spectrum displays were not yet commonplace among amateur transceivers. Embedded menu items can open the door to near granular level control of your radio’s functionality and features. Then again, if those embedded menus aren’t well thought out, it can lead to awkward operation practices in the field, during a contest, or even during casual operation.

As a radio reviewer, I spend a great deal of time sorting out embedded menu functionality and design. Perhaps it’s for this reason that I so enjoyed reviewing a radio that bucks this trend and reminds me of a time that was simpler, not to mention, easier.

Enter the Penntek TR-35

The new Penntek TR-35 is a four-band CW-only QRP transceiver that is available both as a kit ($279) and as a factory assembled and tested unit ($379). Penntek transceivers are designed and manufactured by John Dillon (WA3RNC).

All of his transceiver kits are available at his website WA3RNC.com.

I was first drawn to the TR-35 after reading the opening paragraph of the product description:

“Compact but powerful 4-band, 5-watt CW transceiver kit that uses no tiny push buttons, and without those seemingly endless and hard-to-remember back menus. There is a knob or a switch for every function!”

Sold!

I considered buying and building the TR-35 kit, but I wanted my eventual review––this one!––to focus on the radio’s functionality and performance. So a factory-assembled and tested unit was right for this purpose, just so that any performance issues wouldn’t be a result of any shortcomings in my kit building skills.

I decided to reach out to WA3RNC and ask for a loaner. John very kindly sent a factory built TR-35 to me along with return postage and a very flexible loan period (thank you, John!). Continue reading A comprehensive review of the Penntek TR-35 four band QRP transceiver →

Articles, Comparisons, CW, News, Portable, QRP Radios, Reviews

Which to choose? The Venus SW-3B or the Penntek TR-35?

May 12, 2022 Thomas Witherspoon 34 Comments

Many thanks to Pat (N0HR) who shared following question in a comment:

Thomas

I simply love your videos – both your impressions of the gear and the activations themselves. Great stuff.

I’m curious – now that you’ve played with both the SW-3B and the Penntek TR-35, which is the favorite? Seems like they’re both roughly in the same price range.

Thanks for your fantastic channel and website

73,
Pat N0HR

Thank you for the kind words, Pat, and great question! Several people have asked me variations of this very question recently.

I like both radios, so I’ll frame this in a way that might help others make a purchase decision.

Spoiler alert: You really can’t go wrong with either radio and I feel it’s more a question of operator preferences. Continue reading Which to choose? The Venus SW-3B or the Penntek TR-35? →

CW, Field Reports, Kits, New Products, News, Portable, QRP, QRP Radios, Videos

Field Report: My first POTA activation with the Penntek TR-35

May 3, 2022 Thomas Witherspoon 16 Comments

My most recent field report and video featured the Penntek TR-35 but it was not my first activation with this fantastic little QRP rig!

I pushed the last field report and activation video to the front of the line so that I could show how CW message memory keying worked in the TR-35’s updated firmware. It was, in my opinion, a major upgrade!

What follows is my field report from April 1, 2022: my first POTA activation with the Penntek TR-35. This video was made a week or so before I learned that WA3RNC was working on the new firmware.

Side note: If you’d like to read my full review of the TR-35, check out the May 2022 issue of The Spectrum Monitor magazine.

Although I’d used the TR-35 in the shack for more than a month I was eager to find an opportunity to take it to the field. April 1, 2022 was that day and I made a little detour to one of my favorite local POTA sites to break in the TR-35… Continue reading Field Report: My first POTA activation with the Penntek TR-35 →

CW, Field Reports, New Products, News, Portable, QRP, QRP Radios

Field Report: Testing the new Penntek TR-35 firmware during a POTA activation!

April 25, 2022 Thomas Witherspoon 18 Comments

Since I have a busy family life, I always look for opportunities to fit a little field radio time into my schedule.

My policy is to always keep a radio field kit in my car or truck so I can take advantage of any last minute opportunities.

On the morning of Wednesday, April 20, 2022, I was scheduled to take my car in for warranty/recall servicing at the dealership. I decided in advance that if the service could be completed in two hours or less, I’d relax in their waiting room with my MacBook, drink a cup or two coffee, and attempt to make a dent in my email backlog.

If the service was going to take longer than 2 hours, I decided that I’d use one of their loaner/courtesy cars and activate a nearby park.

The dealership is about 45 minutes from my QTH and I’ve activated most of the parks nearby it, save one: Holmes Educational State Forest. I’ve been wanting to activate this park for ages, but my travels these days simply don’t take me in the direction of the park very often; it’s a good 75 minute drive from my QTH.

Uncertain how long the dealership would need my car, I grabbed my SOTA backpack that had a full field kit inside based on the Penntek TR-35 transceiver.

TR-35 Upgrades!

Why the TR-35? Because I was testing new firmware that added a huge upgrade: two CW message memories!

I won’t go into details about the new upgrade in this field report since I describe it both in my activation video (see below) and in this post which relays the announcement from WA3RNC.

Suffice it to say, I was itching to see how well the new message memories work during a proper activation.

Front of the line

Since this upgrade was just made public, I thought those of you who either own the TR-35 or are plotting to purchase the TR-35, might want to see it in action. For this reason, I pushed this video and field report ahead of all of the others in my pipeline.

The really weird part about publishing this video so quickly is that one of my next field reports and videos will actually feature the first time I took the TR-35 to the field about 3-4 weeks ago! Back then, CW message memory keying wasn’t even on the table.

Activation time

I arrived at the dealership around 9:00 AM (local) and the first thing I asked was, “So how long do you think this will take?” The representative looked at the work to be performed and said, “Three or four hours, likely. If you’re in a rush, maybe two hours.”

I decided I wasn’t in a rush because I’d much rather be playing radio at a new-to-me park than sitting in a waiting room.

I asked if I could borrow one of their courtesy cars and he replied, “We assumed you might want one Mr. Witherspoon, so we already reserved one for you.”