|Good Portable QSO Machine||Time Owned: more than 12 months.|
|Although the RH-20 is no longer available as a kit, it’s worth mentioning a few points from my experience with this radio. I built my RH-20 and RH-40 several years ago, and they were fun, interesting projects. The instructions, documentation, and parts were excellent. Now that the Red Hot Radio website is gone, it’s much harder to get information than when all the documentation and detailed were available for download.|
The RH-20 was designed with a high-headroom, low IP-3 RF/IF section, so it can handle strong signals without de-sensing and IMD. It does a pretty good job generally, but cannot handle 100W signals on other bands when the other transmitter is within a few hundred yards, based on my experiences during Field Day. Nevertheless, the receiver is selective and has a good CW sound. Sensitivity is good, noise and hiss are low, and tuning is smooth and at a comfortable rate. The AGC performance is modest, but this avoids problems associated with AGC. Other reviewers have mentioned the nice receiver, and I agree with most of those favorable comments. There is some VFO drift, particularly when you use the rig for winter camping and start it stone cold. Other receiver issues are that receive current is high, because of the high-IP3 IF amp, and the audio output is sufficient to damage your ears if you run it too high. You can deal with these issues yourself if you like mods.
The audible frequency annunciator (AFA) in the rig works well, and offers two choices for use. You can have it send your frequency in Morse code when you push the button, or when you change the frequency. I like the AFA feature when operating in a sleeping bag. Since there is no dial readout, you need something to know where you are, especially with the ten-turn tuning pot.
Most of my gripes about the rig concern the transmitter section. In particular, the RH-20 and RH-40 radios both have a high-gain multi-stage TX section running at the operating frequency, and despite good layout, these rigs are only conditionally stable. They are fine running into a 50-ohm load, but if you run them into a reactive load, like a real antenna or a tuner that’s poorly adjusted, they generate parasitic oscillations and spurious outputs. I saw this on my HP 141T analyzer, while adjusting a tuner. Once I saw it, I felt sick. Ignorance is bliss. I tried various tricks to correct these problems, without much success. I suspect that many other QRP rigs have similar issues. Designers need to aim for unconditional stability in any QRP radio intended to work into compromised antennas in the field. 50 ohm resistive loads exist mostly in labs.
I contacted Red Hot Radio, and they acknowledged my complaint, and suggested that support might be provided eventually – but there was no support, either directly or on the website. I did find that I could use my RH-20 and RH-40 on the air as long as I adjusted my antenna tuner for very little reflected power. I would be very interested in hearing from anyone who has succeeded in stabilizing the Red Hot transmitters.
Other reviewers have mentioned the fact that the rig’s case is much larger than needed, but this is a plus if you want to include a tuner, batteries, speaker, or other mods. If you have one of these rigs, you’ll probably want to upgrade the keyer chip to the TICK-4, available at Kanga for $15 – this is a BIG improvement, because your keyer settings are remembered after the rig is powered down.
Since the keyer chip is a DIP-8 and goes in a socket, this is a must-do upgrade if you have a Red Hot.
In a sense, the RH-20 and RH-40 are collectors’ items now. They are attractive, fun to operate, and they will reward you with plenty of nice QSO’s. Just remember to operate them into a 50 ohm load!
72 and 73 – George KX0R
|good little radio||Time Owned: more than 12 months.|
|built her few years ago|
0/5 rating is too crude, give it a 4.3
good instructions, good parts, straight forward
to build, worked when finished,
very good looking box, audio freq read out
and tic keyer, receiver is pretty good,
enought pwr for regular day in day out contacts
easy to use in the dark without having to
turn on a flash light
could use better agc
but most little mono band qrp xceivers
iv used have the same poor agc probs
much much better than most other qrp kits
ive built and run
wish I also had the 40 meter version
yours truly mac w8znx
|gets out effectively||Time Owned: N.A.|
|My Red Hot 20 pros: good wide band coverage (especially compared to the SST); RIT; audible freq annunciator; ten turn pot tuning; built in keyer; full qrp gallon of 5 watts makes it vy effective; attractive case.|
Red Hot 20 negatives: substantially bigger than many other competing rigs (ie the K1 gets a lot more features/bands in a similar sized rig); and too much audio! This is one of those rigs that can and will blow the headphones off your head if you jack the AF all the way up to pick up a faint signal and then turn the dial onto a 579 station. I use mine with speakers and it has more than enough audio to drive speakers.
In summary - this rig will increase your qso ratio if you're used to running 2 watts out of qrp rigs - the difference between 2 and 5 watts seems bigger than the difference between 5 and 15 watts. If you're a former military op who is addicted to headphones this rig would require a mod like resistors in the headphone jack.
|Great kit. Perhaps the best bang for the buck in ham radio.||Time Owned: 6 to 12 months.|
|This is one of the best kits on the market today. It breaks new ground for a kit, being the first with integrated keyer, Audio Frequency Annunciator, and the front end is crush proof. Friends in Europe who have built the kit say that it never overloads. Great attention to detail, every part fits, no bending of leads. Not a beginner kit, over 300 parts. I would rate this a 10 on a scale of 5 if I could. My rig of choice on 20 meters. Sold my K2, but will never sell my RH20.|
|Kit for DX QRPer||Time Owned: unknown months.|
The 5Watts output is only satisfied with this kit. The other mono-bander remained 2-3 watts around this is an important role in DX-QRP. The kit is fairly difficult. The kit is unique its step by step construction. But still need alignment after its completion. My RH20 AGC does not work perfect, I need more time to be a perfect one. Still I like one which gives me a chance to think about the circuit and room for improvement.
|Precision design; high performance||Time Owned: unknown months.|
|I love the fact that even the circuit board is red! And the case looks great. Take some time building it and check parts twice before soldering--the board has to be crowded to pack so much into such a small space and it has plated through holes. But it's fun to build.|
You wouldn't believe this is a high performance rig when you see just three knobs on the front panel and no dial or display. But a tiny switch activates the AFA to give the frequency in morse. And another steps the keyer through its modes.
The receiver sounds great. The tuning is smooth and the rate is just right. The T/R switching is completely pop-free and almost fast enough for break-in.
I power mine from a 4.5 A-H gel cell and it's chirp free.
|Fancy red case but nothing special inside||Time Owned: unknown months.|
|Received one from local friend who could not get it working and asked if I would look at it. Got it running. Its the same as the norcal club kit with the published mods. Like the norcal version, receives well. But also like the club version, it has a tendency to chirp/whoop. It draws alot of current. I did a double regulation mod to the VFO and got it fairly stable, but it still likes a stiff power supply. |
|A lot of fun in a little package||Time Owned: unknown months.|
|This kit was just plain fun to build. I modified mine for XIT / RIT, and a switch between 1 KHz and 8 KHz incremental tuning range. RCVR is very good, and have worked DXCC in a few short months. This radio does not like weak power source, however. A weak source, or thin supply cables leads to chirp in mine.|