I have an IC-21A coming this week w/o a power cable. I owned one of these some time back and recall it was a Molex connector (?) but not sure of the A X B- maybe 3X4?
The 21A manual I found on line showed photos of the IC-21 which used an octal or 11 pin connector.
Any help out there?

Tnx,

Dale W4OP

Sensitivity has not been an issue with HF amateur transceivers for decades. The limit to HF sensitvity is: manmade, atmospheric and galactic noise. I can't think of a transceiver  that lacked sensitivity. In fact, jut the opposite is many times the problem. I hear guys on 75M all the time saying they are using their preamps- not even realizing what this does to receiver specs.

Dale W4OP

I'll 2nd Bob as a source- honest and fast shipping.

Dale W4OP

I have just posted a photo of the station accessory I built for my Hallicrafters FPM-300 MK II; dubbed  FPM-300SA
The accessory adds:
1. Hi Fi front firing speaker
2. Switchable 14dB gain front end preamp.
3. audio CW filter with an active audio stage to make up for the filter's insertion loss
4. RIT This is really necessary if you don't want to be listening to the other station at a 1400 Hz tone
5. Internal 200W dummy load
6. Custom wattmeter using a meter from a parts FPM-300
Click on the photo of the FPM-300 in the bottom row:

http://www.parelectronics.com/vintage-radio-restoration.php

Dale W4OP

The RF Connection (therfc.com) and likely many others sell an SO-239 to 3/8-24 threaded adapter. This would make a very robust point for your vertical. I don't see it on their site- but have bought many from them.

Dale W4OP

I don't think the design will hold up at all. That concept is OK for 2M and up, but a 54" tube or rod (assuming this antenna is outside) will quickly destroy the center connection of an SO-239.

Stainless is not a great conductor for VHF and up.
Brass is  a lot harder than copper.

Dale W4OP

You should never need a preamp below 20M unless something is wrong with the rig or you are using a very low gain RX only antenna.
Using the preamp on the low bands degrades your IP3 and blocking dynamic range.
Here's a short article on using preamps and attenuators on HF. VHF/UHF is a different story.
http://www.arraysolutions.com/Products/appnote_preamps.htm
YMMV,

Dale W4OP

The NB doesn't "know" what band you are on. Classically, the NB is in the first IF before any narrow filtering. So the NB is seeing  more of the band than you are listening to. This is necessary to allow for minimum lag in the blanking. If signals into the NB are too high, it will produce distortion. Were you using the preamp on the bands below 30M? Sometimes- particularly  evenings, it may be necessary to switch in some attenuation on the low bands.

Dale W4OP

How much higher? VSWR is a function only of the mismatch between the transmission line and the antenna. Power is not in the equation. almost always  when I see higher VSWR at higher power it is because of poor design the instrument used to measure VSWR.
Dale W4OP

Hi Dave,
You should be able to use an NE555 timer chip in astable mode and a transistor switch to toggle the UP or DOWN circuit (this assumes when  the upper or lower limit is reached, it rolls over). Then also monitor the squelch line to disable the astable when the squelch is opened for a preset dwell time. A second NE555 would be configured in timer mode to set the dwell time.

GL,

Dale W4OP

I am seeing that exact situation on my Hallicrafters FPM-300 MK II. The VFO runs straight to the 9MHz mixer on 80M, while all other bands go through a het /mixer with gain. The  output into the 9MHz portion is exactly 3dB lower on 80M and this shows up in the final PA output level.

Dale W4OP

from G3RZP:
Not totally true, because especially on frequencies below 10 MHz, the rise in noise on connecting the antenna may be caused by multiple signal intermodulation as well as, in addition, phase noise.

Higher sensitivity was a goal in the 1930s, when it WAS needed. Unfortunately, it's stayed as necessary marketing hype 70+ years later, possibly because of confusion with noise figure requirements at VHF/UHF.
--------------------
No argument there at all. I am well aware of phase noise and IM although phase noise may have been a less of an issue with the good PTO's like Collins or Drake or TenTec  than it is with some of today's DDS stuff.
And, as you said, VHF/UHF is a totally different story. On my 23cM EME system, I can make use of LNA's with  NF below 0.2dB.
73,
Dale W4OP

Steve is spot on. Sensitivity is a non-issue. If you hear more noise when you connect your antenna- then you have enough sensitivity.
I get a kick when I hear someone comment on how "quiet" a receiver is. This most assuredly is a result of how the AGC is set up, as our HF noise floor is not determined by the receiver, but rather by  manmade, atmospheric and galactic noise.

Dale W4OP

My first experience  with Heising was an early Heath  11M HT that I put on 10M back in the '60's.
If you have never heard Jean Shepherd's WOR segment on Heising modulation- you'll love it.
Go to  http://jeanshepherdpodcast.blogspot.com/

and scroll down to:

WOR - 1965_01_29_Ham_Radio

Guaranteed to bring back early novice/general memories.

Enjoy,

Dale W4OP

Can you hear the VFO running on a general coverage RX or see it on a freq counter?

Dale W4OP