Comments for Engineering Radio

Comment on Tube transmitters vs Solid State transmitters by Paul Thurst

Paul Thurst — Mon, 06 Feb 2012 20:11:15 +0000

Stephen, I have little or no experience with HF broadcast transmitters, however, they are similar in form and function as AM aka MF/MW transmitters. Thus, I would put forth the following:

AM tube transmitters are rugged but less efficient that solid state counterparts. Older tube transmitters may not have spare parts. AM solid state transmitters are more efficient, but also more expensive. Also, some brands of transmitter are more complicated and require a higher level of understanding than others.

Continental HF transmitters have Solid State Modulators (SSM) which are standard with all new transmitters and I believe available as retro-fit for older models.

If money where no object, I would go for the solid state unit.

Comment on Tube transmitters vs Solid State transmitters by STEPHEN GARBA

STEPHEN GARBA — Sun, 05 Feb 2012 14:32:30 +0000

Please can some one out there outline the tube and solid state transmitters advantages and disadvantages for high power short wave transmitter?

steve

Comment on How the Cold War was won by Paul Thurst

Paul Thurst — Sat, 04 Feb 2012 13:25:11 +0000

Dave, I didn’t know that the AF was still using CDDAs, that is interesting. I suppose there is more Bear air/army traffic than naval activity these days, as most of their old fleet is now razor blades.

I know that the FLR-9 at Clark was turned into an amphitheater after the US pullout in 1991.

Comment on What is the deal with those FEMA/DHS AM backup transmitters? by When all else fails « http://frrl.wordpress.com

When all else fails « http://frrl.wordpress.com — Sat, 04 Feb 2012 07:44:22 +0000

[...] Read the entire posting here – http://www.engineeringradio.us/blog/2011/10/what-is-the-deal-with-those-fema-dhs-am-backup-transmitt... [...]

Comment on How the Cold War was won by Dave Jeffries

Dave Jeffries — Sat, 04 Feb 2012 01:55:07 +0000

I believe the AF is still operating the AN/FLR-9s The one we had at Misawa AB in Japan (FLR-9a) was a newer one with a few differences than the stock -9. Our friendly “Bear” still operates a lot of HF equipment and it pays to know from where it is working. If you check Google Earth you can quite clearly see the one at Misawa. Look Northwest of the runway and across a small lake to find “The Hill” as sigint facilities are often called..

Comment on The Gates BC250GY transmitter by Paul Thurst

Paul Thurst — Thu, 02 Feb 2012 22:57:59 +0000

Dewey, like all things, it depends. The variables are dial position; lower frequencies travel further due to better ground conductivity. How much co-channel interference, especially at night and how high is the ambient electrical noise level in the reception area. This station is on 860 KHz in a fairly rural environment, thus I’d estimate the listenable range to be a 7-10 mile radius from the tower at 250 watts.

Comment on The Gates BC250GY transmitter by Dewey Jacks

Dewey Jacks — Thu, 02 Feb 2012 19:43:39 +0000

How far out does a 250 watt AM broadcast transmitter like this one reach? Pretty neat to see old radio broadcast gear still going!

Comment on The Gates BC250GY transmitter by Paul Thurst

Paul Thurst — Thu, 02 Feb 2012 17:30:42 +0000

Bill, you are correct. That’s what I get for glancing at the parts list and not looking at the schematic. What is surprising to me is that they were still using mercury vapor rectifiers in 1975. I think by that time they had developed solid state rectifiers for this voltage and current.

Comment on The Gates BC250GY transmitter by Bill McCarrey

Bill McCarrey — Thu, 02 Feb 2012 16:39:40 +0000

I may be nitpicking, but i’m pretty sure the RF and modulator tubes are 810′s. 8008′s are mercury vapor rectifiers. (not meant to offend)

cheers!

Comment on Coast Guard Radio Guam/NRV, part II by Fred Wassmer

Fred Wassmer — Wed, 01 Feb 2012 23:38:57 +0000

Thanks for the article Paul, both parts. Good memories.
NRV 86-88