Thanks Steve & Dave,
Some useful ideas, I'd already spent some time looking at the cct diagrams of the IF unit to see excatly what happens when the? compressor (RF Clipper) was switched in, I need to have another look but it seems that as to be expected the mic gain is increased to drive the clipper which might explain why the mic is more sensitive to RF. What I might try is providing the mic bias from a battery & not form the 8V line on the Mic socket.
I didn't mention that when running 250W on 2m from a transverter there's no problem with RF.. The easy solution as Dave suggested is to find a headset with a (small) dynamic mic.

73...

Ken

G3LVP

I learned several years ago that the Kenwoods prefer a dynamic element as opposed to an electret-conderser type element. The electrets work great on the vhf and uhf mobile rigs, but touchy on the hf units. From Heil Microphones: "Condenser microphones are typically found in the studio. The element is made up of a thin film coated with a conductive material such as silver or gold which is suspended over a polarized (powered) backplate. This condenser diaphragm is part of an electrical circuit that changes voltage with movement and this voltage becomes the output of the microphone. Sensitivity, wide frequency response and transient response were always the performance advantages of condenser microphones over ribbons, dynamics and all other types of microphones.

Unlike dynamics or ribbons, condensers require a power source to operate. This power is typically delivered via an external “power supply” or something called “phantom power”. Phantom power is a dc voltage fed back through the microphone cable from the console or mic preamplifier to the microphone to run its internal electronics. The term “phantom” was coined because there is no additional wiring or connections to carry the dc power from the console to the microphone. Most all consoles or mic preamps have a built-in 48 volt phantom supply that can be sent to the condenser mic up the mic cable.

The phantom power situation is also something you must be careful of. These microphones are more susceptible to RF and electrical interference since you have dc voltage being fed on the exact same two conductors as the audio from the microphone to the console. Because there is no heavy voice coil attached to the diaphragm."




Heil recommends a dynamic element for the 870S, and that configuration is what I used with my 850S.

开云体育

Here’s a YouTube video of a ham testing a cheap electret mic on a Kenwood. He’s testing and setting the mic parameters using his Kenwood. Try this. If it doesn’t work, then check the mic pin-out. If correct then try using the mic on another Kenwood. If that works then try another cheap mic on your Kenwood. If that fails then you may have to do a diagnostic on the audio input of your radio.?

开云体育

It seems unlikely that anyone else has come across this minor problem but worth a try!

Instead of the standard Kenwood mic I sometimes use a basic (cheap!) single earpiece / with electret mic on my TS850S. All is OK unless I try to use speech compression then unless I keep the Mic gain well down I get RF feedback even when running into a dummy load.

I've tried a combination of inductor in series 1n C's to ground, ferrite rings, keep the RX audio to zero etc. all to no avail. The results are the same on all bands 80 - 10m. I? use a similar headset on my H/B HF transceivers without any problems.

Any suggestions? Maybe buy one of these absurdly expensive headsets that are advertised in the Radio Mags.? I wonder if they suffer with the same problem?

73...

Ken

G3LVP

Here is a video that might help


Jeff - NZ2S

Here is a place to start


Jeff - NZ2S

Thanks Donald!
I'll look at the subgroup as well.
Hope this isn't too obscure to get clarity on.

Charlie

We're a small group but I hope you find an answer here or in this TS-870
specific group, which has about 1/4 of the members we have, though it is just
for that model:

/g/TS-870


Donald KX8K



On Fri, 28 Oct 2022 14:26:52 -0700, "Charlie Fellenbaum - WB4FAW"
<charlie@...> wrote:

I have a lovely new-to-me TS-870, the nicest radio I've owned to date. I got it in part because it supposedly interfaces well with a computer allowing easier programming and other digital advantages, which hopefully include logging.

I understand that when new, these came with a Windows program to allow this communication, requiring only an RS-232 Com to USB cable, which I already have.
Does anyone have a source for the original software, or other information to help me get started with this?
Of course the original version probably won't even load on Windows 10, but gotta start somewhere.

And if there is another group that might be helpful that I could post this topic to, please let me know.

Charlie
WB4FAW
Longmont, Colo

----------------------------------------------------
Some ham radio groups you may be interested in:
/g/ICOM /g/Ham-Antennas
/g/HamRadioHelp /g/Baofeng
/g/CHIRP

I have a lovely new-to-me TS-870, the nicest radio I've owned to date. I got it in part because it supposedly interfaces well with a computer allowing easier programming and other digital advantages, which hopefully include logging.

I understand that when new, these came with a Windows program to allow this communication, requiring only an RS-232 Com to USB cable, which I already have.
Does anyone have a source for the original software, or other information to help me get started with this?
Of course the original version probably won't even load on Windows 10, but gotta start somewhere.

And if there is another group that might be helpful that I could post this topic to, please let me know.

Charlie
WB4FAW
Longmont, Colo

Since we don't have file storage, attached is a catch-all document on soft and hard reset procedures for various Kenwood radios.

I'll be uploading this into the files section (in a few minutes) of our HamRadioHelp group:




Donald KX8K

Hi group...

My 30+ years old TS-450 has developed a moderate loss of gain roughly a few minutes after I turn it on, which I noticed some time back.

I was using it to monitor the output of my signal generator for hum, and I may have hit the 450 with a couple of volts of RF...

Where is it best to start looking, or is this not an uncommon issue...??

Thanks for your advice...

73...Jordan VE6ZT

Hi group...

My 30+ years old TS-450 has developed a moderate loss of gain roughly a few minutes after I turn it on, which I noticed some time back.

I was using it to monitor the output of my signal generator for hum, and I may have hit the 450 with a couple of volts of RF...

Where is it best to start looking, or is this not an uncommon issue...??

Thanks for your advice...

73...Jordan VE6ZT

开云体育

A friend and I are trying to bring a TL-922 back to life and obtain full power output. The amp is working with a new HV supply and new 3-500Z tubes but cannot achieve full output as specified. It seems to be putting out about half the power that it should. If anyone on this reflector has any clues as to where we should be looking for some component which may be failing or have failed and would cause the low output, please reply. We are driving the amp with 100W and are seeing CW outputs at about 600W, key down, and SSB outputs of about 800W peak.

Kenwood Dual Band HT, Speaker, Crystal
Filters, Microphones, Mobile mount,
Extension feet, and more For Sale

.

Kenwood TH-G71 Dual Band HT:

The Kenwood TH-G71A is a dual bander with all
the right features.

Besides being easy to use, the TH-G71A also
boasts power up to 6 watts (VHF) or 5.5 (UHF)
with external power. You also get .5 W or .05 W.
200 memory channels, with six alphanumeric
characters. Multiple scan functions are available.

It includes the PB-39 high powered battery,
BC-17 AC Charger, Belt Clip and SMA flexible
antenna. Only 2.3 x 4.5 x 1.3 inches.

Features:
200 Alpha Memories
Key Illumination
Multi Scanning Modes
Built-in encode/decode
Easy to use menu
3 RF Out Levels

This one looks like new, and works the same.
In includes a PB-39 H, high capacity 1450 Mahr
battery plus the regular one. Both hold a
charge and work well.

This one also includes the BP-19 desk charger,
and the wall wart charger.

With paper work for $145.

.

Kenwood SP-23 External Speaker:

The Kenwood SP-23 base speaker matches many
Kenwood transceivers including the TS-450, TS-570,
TS-590 and TS-690, and many, many more.
This versatile 8 ohm speaker features a metal cabinet
with flip-out tilt bar. It has a 3 inch speaker element
rated to 1 watt, with a 300 to 5000 Hz response.
The rear panel features two screw connections,
and includes a 3 foot audio cable.

It is 4.8 x 3.75 x 9.25 inches, and weighs 2.8 lbs.

This particular speaker works fine, and looks
like new, with no scratches, dent, or dings.
With cable and paper work for only $85

.

Kenwood Crystal Filters
All work as they should and are solder in type.
They look fine also, as if that matters
for a filter inside the rig.

Kenwood YK-88 SN Crystal Filter:

These filters are used in rigs such as the
TS-120, TS-130, TS-430, TS-440, TS-520,
TS-530, TS-820, TS-830, and others.

Kenwood YK-88 SN, 1800 Hz SSB Filter
This is the narrow SSB filter, that can
also be used for wide CW. $79

Kenwood YK-88 C, 500 Hz CW Filter $79

Kenwood YG-455 C, 500 Hx CW Filter
This is used in the 455 KHz IF, and will work
in a wide variety of rigs. $125
.

Kenwood MB-430 Mobile Bracket:

The Kenwood MB-430 is the mobile bracket
that is used to mount the Kenwood TS-430,
TS-440, TS-450, R-5000 and maybe others.

This one is in nice shape and includes
the four screws (and washers) for attaching
it to the rig.

These are no longer made and are somewhat
rare.

Buy this one for $45.

.

NEW Kenwood MC-90 Desk Microphone:

The Kenwood MC-90 is a high quality DSP-compatible
desk mic. It is supplied with two interchangeable
heads. One has a flat frequency response for
good overall performance, while the other offers
exceptional clarity and an output level characteristic
that peaks at around 3 kHz, making it ideal for DX
applications.

There is also a 3-position (M, V1 or V2) switch
on the base to tailor low-range cutoff frequency
to suit the operator. The 250 ohm mic terminates
to a standard 8 pin mic plug.

This particular mic is NEW, still in its original box.
I don't think it has ever been out of the box.
Obviously, that means it is in perfect condition.

These normally sell for about $300.
Buy this one for only $240.

.

Kenwood MC-50 Desk Microphones:

The Kenwood MC-50 is a dynamic cardiod
desk microphone. It features a push-to-talk
and lock button, and has a four pin plug.
This mic is connector switched, dual impedance --
50k ohm and 600 ohm. Frequency response
from 150 Hz to 10 kHz.

The MC-50 is the perfect match for many of
classic Kenwood transceivers such as: TS-120S,
TS-130, TS-520S, TS-530S, TS-820, TS-830S and others.

This one is slightly used, but in great
shape both electrically and cosmetically.
It looks close to perfect. $75

.

Kenwood MC-43 Hand Microphone:

The Kenwood MC-43 is the standard hand
microphone used with many, many Kenwood rigs.
It has a round 8 pin connector and will work
with most any Kenwood rig that takes this connector.

The top of the mic has up/down buttons to
change the frequency.

This one works as it should, and looks
like new.

With paper work for only $40.

.

10 meter Crystals for Kenwood HF Rigs:

These crystals work in the Kenwood TS-820
for sure (they have been tested in a TS-820),
and probably will also work in most of the
other Kenwood "Hybrid" rigs. Please check
your manual.

Set of three crystals
These crystals will restore all three 10 meter
segments. They are used after someone
"converted" your rig to 11 meters, and you
would like it back on 10 meters.
They simply plug in, so no difficult surgery is
needed.

$35 plus shipping for the set of three.

.

Linear Amp Switching Cables for Kenwood Rigs:

This cable goes from a Kenwood transceiver to a linear
amplifier to switch the amp from transmit to receive.

One end has a DIN connector, as is used with most Kenwood
rigs. The other end has an RCA phono plug, as used by most
linear amplifiers.

Before using this cable, please check the switching
capabilities of your transceiver, and the requirements
of your amplifier.

Cable for switching the T/R relay Only $15.

Cable with ALC control, in addition to T/R switching. $20

.

I also have many other accessories available such as many
different types of microphones, HTs, VHF and UHF rigs, HF
and VHF/UHF antennas, connectors, miscellaneous accessories,
etc.
Just too many to list here. Please e-mail your requests.

.
Prices do not include shipping from Florida.

Thanks.

73,

Ken, W8EK

Ken Simpson
E-mail to W8EK at FLHam.net or W8EK at arrl.net
Voice Phone (352) 732-8400

On Sun, Aug 7, 2022 at 01:10 PM, Bob wrote:

If you build this you can test it with 12 volts DC and verify current draw etc before you connect to your radio and amp.

Hi Bob.. Just wanted to jump in and say that I built the circuit you provided and it works like a champ!! Thank you so much.